Electric Fuel Pump Installations

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bbodie52
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Electric Fuel Pump Installations

Post by bbodie52 »

:think: :idea: I have seen the topic of electric fuel pumps come up frequently on the Corvair Forum. The installation procedures outlined below were used to answer a question regarding the proper installation of an electric fuel pump elsewhere on the Corvair Forum. I felt that carrying that same information over here would help it to remain visible to more Corvair owners in the future. In addition, the decision as to whether or not to remain with a mechanical fuel pump or switch to an electric pump is also addressed toward the end of this topic.

Since I had never installed or used an electric fuel pump in a car, I did not know of a weakness in electric fuel pumps that limits their installation to distances that are close to the fuel tank. It would be easy to assume that, when replacing a mechanical fuel pump with an electric fuel pump, the physical layout and configuration used with the mechanical fuel pump installation would be similar to that needed by the electric fuel pump. Apparently this is not true! The functional purpose may be the same, but the installation requirements are not.
Airtex Fuel Pumps wrote:Be sure to pick a location within 2-3 feet of the fuel tank!
Airtex Fuel Pumps
:wrench: How to Install a Universal Electrical Fuel Pump


Airtex Fuel TV :link: http://www.youtube.com/user/AirtexFuelP ... ture=watch

:link: http://www.airtexproducts.com//
Mine has mechanical fuel pump how can I convert it into a electric?

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Airtex Fuel Pumps --
There are many steps to this process depending on vehicle type, engine size, pump placement, etc. We address some of these issues in our video. If you need more detailed help on your application please call our free Tech Support Hotline 800-424-7839 & we'd be happy to walk you through it. Thanks.
=============== BACKGROUND INFORMATION THAT MAY BE HELPFUL ================

I recently did a comparison between standard Corvair mechanical fuel pumps and aftermarket electric fuel pumps for another Corvair Forum member. I thought that you would find that material informative, so I have included it here.

Replacement mechanical fuel pumps are reliable and relatively inexpensive. A good electric pump, with proper safety switching can cost many times the price of a new mechanical pump. Corvair mechanical fuel pumps have been widely tested in hundreds of thousands of Corvairs for 40-50 years, and they are a proven product with good reliability. They are also easy to remove and replace. I would suggest reading and following the shop manual to properly test and diagnose a suspected fuel pump problem.
1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL.pdf
1965 Corvair Chassis Shop Manual - SECTION 6M - ENGINE FUEL
(8.87 MiB) Downloaded 215 times
If you feel that the fault is a bad fuel pump, replace it. But I would recommend against a conversion to an electric fuel pump. It is not worth the expense. You could purchase two mechanical pumps and keep one in the trunk as part of a spares kit, and still spend significantly less than the cost of an electric pump conversion. An electric fuel pump is not inherently more reliable than the standard Corvair mechanical pump. It simply substitutes an electric motor for the engine to provide the power source to pump the fuel. The electric fuel pump, including the safety devices to ensure its operation only when the engine is running, adds complexity which can actually increase the possibility of a system failure.

The material below will provide you with good information.

:tongue: :think: Tips From CORVAIR UNDERGROUND...

http://www.corvairunderground.com/fuelpump.htm
Let's Talk About

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Corvair FUEL PUMPS

This is always a controversial subject amongst Corvair owners. But a great deal of the controversy is self inflicted. Mechanical or electric fuel pumps? Let's try and sort this out.

MECHANICAL FUEL PUMPS - These are the pumps that came standard with all Corvairs from the factory. The mechanical pump is a simple diaphragm type that is operated by a push rod which rides on an eccentric on the crankshaft. The pump develops suction which draws gas from the fuel tank and distributes it to the carburetors.

It would be simple to say that all mechanical Corvair pumps are the same - but alas, that is not the case. The original 1960 models had a pump that appears to be the same but has a longer rod exiting the bottom of the pump. In turn a shorter pump pushrod was obviously used. This design was carried over into 1961 models for an uncertain period of time. This is why if you own a 1960 or 1961 you should always measure the overall length of your pushrod before you replace the pump.

In that same vein I would highly suggest that if you find you have one of these earlier pumps you should convert it to the 62-69 type. Why? because it's easy and cheap to do and there is never a question in the future as to which pump you're using. If you should be unlucky enough to find an NOS earlier pump do not be tempted to use it!

These 60-61 pumps were last produced well over 30 years ago and that pump will be too old to reply on. To make the conversion simply get one of our part number U-481 pump pushrods.

Now let's go back 18 years ago to 1992. One of the largest makers of Corvair fuel pumps got a defective batch of diaphragms. THIS HAPPENED ONCE and only in 1992. But the repercussions have lasted ever since. The problem was corrected within a few months BUT because this manufacturer sold to many different retailers it made it appear that numerous manufacturers were putting defective pumps on the market. To make matters worse, some of those retailers moved very few Corvair pumps, so for years (even to the present) some "brands" (labels, really) still sell defective Corvair pumps - all ones made in that original batch 18 years ago.

Well, bad enough you say. Oh it can always get worse - and it did. Back in the early 90's a small parts vendor saw an opportunity. Because everyone at the time was in a virtual panic this vendor saw an opportunity to promote their fuel pumps. An abnormal amount of negative advertising and outright nonesense permeated the Corvair grapevine. The claim, of course, was that this vendors fuel pumps were perfect while everyone elses were bad. But there was an irony here.

As time went on it became more than apparent that the vendors fuel pumps were actually worse than everyone elses. Where their pumps came from were anyone's guess, but by hundreds of defective pumps and 3 different, but failing, revisions later the matter was dropped.

But that wasn't enough. During this timeframe numerous Corvair experts (some real some self-proclaimed) wrote articles that only clouded the issue even worse.

Some claimed that rebuild kits were the only answer. Ironic again, because the few remaining rebuild kits also suffered from the diaphragm problem, possibly because they had been the original supplier for this part from the beginning. Some claimed that certain visible features could warn you of doom. Visible reinforcement fibers in the diaphragm, the type of screws holding the pump body together, even the precise length of the lower diaphragm rod were all to be worshipped. While it's true that some of these identities sometimes had validity none of them were absolute. The issue of the diaphragm rod length was especially absurd.

It's true that the rod length has to fall within certain parameters, but the miniscule measuring of this rod was misleading overkill. The amount the rod protrudes from the pump casting can still vary up to at least 1/4 of an inch and still be within specs.

Take all of the above and horsewhip it to death from 1992 to the present and what can you expect? If you study the psychology of panics most of them look a lot like our fuel pump example. An issue can be twisted and confused so much for so long there is no way to untangle it.

Then we have to think that many people quit driving their Corvairs? No, a "white knight" came to some owners rescue. The electric fuel pump is used on nearly all modern cars. Electric pumps are generally reliable, and are readily available. So why isn't that the end of the story?

I have said since Day One that I would never talk a happy electric fuel pump owner out of their pump. That has never really been the issue. The issue are new Corvair owners and what they should feel compelled to do. I think it's irresponsible to tell a new owner that he has to get rid of a perfectly functioning mechanical pump and replace it with an electric.

Electric fuel pumps cost more than mechanical pumps, especially when set up safely, take a bit of work and knowledge to retrofit and have their own problems (as do all mechanical devices). Bottom line - they are unnecessary, but if you really WANT one (as opposed to being convinced that you MUST have one) then that's your decision.

But what if your mechanical pump has failed?

FIRST - Make sure it HAS failed. I believe that many fuel pump "failures" have nothing directly to do with the pump. The most common of these is when you develop an air leak in the incoming fuel line. Spots to look for trouble include the rubber connecting line just behind the firewall (old cracked hose or loose fittings are the culprit) and make sure the fittings where the incoming line connect to the pump are good. These air leaks can be transient or very specific and repeatable - all related to ambient temperature. If you think your fuel pump has quit pumping check these spots first.

And then there's leaks, both internal and external. Of course the biggest boogeyman is the internal leak that pumps gas into your crankcase causing everything from noisy lifters all the way to a trashed engine. This can be serious and I have seen it happen - with both mechanical AND electric fuel pumps - but it isn't so common that you have to spend every day immersed in paranoia about it.

External leaks can happen but they are usually the result of incorrect installation or other misuse of the pump OR you may have purchased one of the brands of pumps that never got sent back from the 1992 recall.

One important point about electric pumps is that if you chose to use one make sure to remember that the incoming line system was not designed to be pressurized.
http://www.corvairunderground.com/pumpleaks.htm
Our own mechanical fuel pump "horror" stories....

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As I've mentioned before, I have nearly 2 million miles of Corvair driving on mechanical fuel pumps. I believe them to be totally reliable.

Never the less, we do no one a service by ignoring actual issues. Rather, it's better to get them out in the open and try to analyze them. Here are the ones I have experienced firthand.

Once my stepson and I were driving his 1969 up to a Corvair event in northern Washington. He hadn't put many miles on the new engine but everything was running well. We had stopped at a Wendy's to eat lunch. The 69 was parked on a pretty steep space where the engine was on the downhill side.

After eating we came out and started the 69 up. It was running fine but I was sure I smelled gas. Went to the back of the car and gas was POURING out of the back of the fuel pump. We immediately stopped the engine and pondered our options (I had brought a new spare fuel pump with us - I carry a spare tire and fan belt too).

Because I couldn't explain why the pump was suddenly "leaking" I asked my stepson to start the motor up for just a few seconds so I could see exactly where the gas was coming from. SURPRISE! Gas wasn't coming out of the pump any more. I was baffled.

We watched the pump for about 10 minutes. Not a drop of gas. We proceeded (cautiously) the further 100 miles to the show. No leaks. Then drove home (about 300 miles) no leaks. In fact, this was 10 years ago and the car still has the same fuel pump on it. Not a drop since.

What exactly was going on? I have my theories, but maybe you have an idea.

Another leak story involves my Ultravan. Because it usually sat for months at a time when it came time to start up for a new season I'd have the engine lid off to watch for problems. The last time it had been started was about 9 months before. This time on startup there was a massive fuel pump leak.

I shut the van down and went inside to ponder the situation. About 10 minutes later I went out, restarted the Ultravan, and of course, no leak. The "leak" never came back - even 4 years and 5000 plus miles later.

Our last example is interesting because it just happened to me 2 days ago (August 30th). I had my daily driver 64 Greenbrier down for about 3 weeks while I rebuilt the carbs, distributor, and alternator.

When all the work was done I did the initial startup and SURPRISE the fuel pump that had been serving faithfully for over 60,000 miles was leaking. But this time I thought I'd just shut down for a few minutes and then restart.

Of course the "leak" was gone. And it hasn't come back.

In all the cases above I DID NOT tighten the screws on the pump - In these circumstances many people retighten the pump cap screws and lay the "leak" on the need to do that. But note that, at the same time, there was a short waiting period between "leaking" and not leaking. I'm certain it was the waiting period - NOT the screw tightening that fixed the problem.

But why is it happening? (Even if just occasionally) It appears that modern fuel dries out the rubber diaphragm between extended intervals of operation. Sometimes (but not usually) the diaphragm material will shrink causing a leak at startup. BUT, once the material is re-exposed to the fuel it "swells up" and re seals.

If you have other ideas let me know.

The last example is what I believe to be very typical. Linda and I drove our 67 out to southern Utah for a Corvair event back in 2000. We had already driven 900+ miles without incident but after meeting up with the Bonneville Corvair club we stopped for lunch (At a Wendys again - hmmmmm I wonder...).

As we left we all drove back onto the freeway and the 67 died out. No fuel. Everyone thought it was a failed pump. But I was suspicious. I went back and checked everything over and noticed that the incoming gas line fitting was loose. Upon tightening it up we had fuel pressure again and finished our trip, including a barren 300 mile return across HWY 50 in Northern Nevada (The world's loneliest highway).

Vacuum leaks anywhere in the incoming line can cause the pump to quit drawing fuel. These leaks can be effected by temperature and other factors. Check these things first , before you assume the pump has failed.
CLARK'S CORVAIR PARTS MECHANICAL FUEL PUMP OPTION (Page 65)
http://www.corvair.com/user-cgi/catalog ... IN&page=65
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Part number C3403A: 62-69 FUEL PUMP REBUILD KITS ARE NOT AVAILABLE
Weight: 2 lbs 4 oz
Catalog Pages(s): 65
Price:
1 - 1 $ 78.45
2+ $ 74.55

==========================================================================
ADDITIONAL ITEMS - Any products listed below are possible alternate choices:
Part number C3403 (Regular): NON-GM FUEL PUMP-62-69 WILL FIT 60-61 IF ORDER C259 ROD

Weight: 2 lbs 4 oz
Catalog Pages(s): 65
Price:
1 - 1 $ 59.10
2+ $ 57.35


CLARK'S CORVAIR PARTS ELECTRIC FUEL PUMP OPTION (Page 66)
http://www.corvair.com/user-cgi/catalog ... IN&page=66
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Part number C10295: ULTIMATE ELECTRIC FUEL PUMP KIT INCLUDES BOTH STYLES OF SAFETY SWITCHES
This part is a Multi Kit, which contains the following parts:
Part Number C5606: 1 x ELECTRIC FUEL PUMP & FILTER -ALSO ORDER
Part Number C5607: 1 x ELECTRIC FUEL PUMP INSTALLATION KIT *
Part Number C5607X: 1 x SAFETY SHUT-OFF SWITCH WITH FITTINGS TO
Part Number C9848: 1 x FUEL SAFETY INERTIA SWITCH

Weight: 2 lbs 8 oz
Catalog Pages(s): 66
Price: $ 241.60


:checkeredflag:
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Re: Electric Fuel Pump Installations

Post by davemotohead »

I run nothing but the Facet pumps! Front or back does not seem to matter? Have one mounted in my engine compartment for over 20 years and still running strong! I install a momentary button under the dash to run the pump to prime the carbs if the car has been sitting for a while so it will crank right up! :tu:
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Re: Electric Fuel Pump Installations

Post by bbodie52 »

:goodpost: :coolphotos:

Good advice and recommendations from your long-term experience! The price is not bad, either -- only about $50, including shipping. The recommended oil pressure-triggered safety switch, filter, and miscellaneous hardware would bring te cost up a bit, but still not too much above the mechanical pump. However, I have to say that I have been involved with Corvairs in my family since 1961, have driven Corvairs with the standard mechanical fuel pump all over the USA and in Europe, and I personally have yet to have a mechanical Corvair fuel pump fail. And if one did fail, a spare pump in the trunk is cheap and easy to swap out. But I guess the same argument could be made for the $50 FACET electric pump. If the safety switch were to fail, it would be easy to wire a temporary bypass to get back on the road too.
Pegasus Auto Racing Supplies wrote:Where is pump number 574A?

574A is not a part number. 574A is the UL Listing number, so it appears on all Facet fuel pumps. The Facet part number is a 5- to 7-digit stamped on the mounting flange (usually 2 or 3 digits on either side of the mounting bolt hole). We can usually cross-reference your part number to one of our pumps.
Thaat being said, can you provide the FACET part number that you utilize on your Corvair? There are about 25 different FACET pump models listed with a variety of different pressure and volume capabilities, ranging in price from $50 to about $140. That, coupled with your recommendation, should make the FACET pump a serious consideration for anyone considering a switch to an electric fuel pump. One source I located on the Web is listed below...

:link: https://www.pegasusautoracing.com/group ... upID=FACET

The Airtex oil pressure triggered safety switch is available for $13.97.

:link: http://www.summitracing.com/parts/atx-os75

Brand: Airtex
Manufacturer's Part Number: 110-OS75
Part Type: Oil Pressure Safety Switches
Product Line: Airtex Oil Pressure Safety Switches
Summit Racing Part Number: ATX-OS75

UPC:080044513926
Switch Material: Steel/Plastic
Switch Finish: Natural
Quantity: Sold individually.
In-Store Pickup: Choose In-store pick-up (OH, GA, NV) on our web site.

When oil pressure drops, Airtex oil pressure safety switches cut the flow of fuel to keep you safe. These engineered and tested safety switches meet or exceed OE specifications to stop your electric fuel pump when your engine stops. Airtex oil pressure switches are important safety features in an accident and can be used with any universal inline fuel pump. These single-inlet, quick-connect outlet switches include gaskets. Stay safe--install Airtex oil pressure safety switches in your vehicles.
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Re: Electric Fuel Pump Installations

Post by Corvair1 »

This installation is from Rafee and it shows the pump instalation and the fuel line cutting and re-rutting.
http://corvairone.com/elecfuelpumpinst.htm#1" onclick="window.open(this.href);return false;"
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Re: Electric Fuel Pump Installations

Post by miniman82 »

And now for the benefits of going 'lectric:

Most of these articles talk about what to do when you have mechanical pump issues; if you had an electric one you'd never have a mechanical pump problem to begin with, so the whole reliability thing goes out the window to me. I hear about far more mechanical issues than electric, so who's really got an agenda here? The parts suppliers who need to sell a mechanical pump to make a profit? I'll go with what works 100% of the time, which is electric.

Apparently, none of them have tried to start a hot turbocharged engine with a mechanical pump after stopping for gas. My experience: all the fuel gets boiled out of the carb and pump, leading to unbreakable vapor lock situation. Only way to start it then is to pour gas directly into the carb bowl, which is not the safest thing on a hot engine. You could let it cool too, but you'll still be stuck cranking the piss out of it attempting to prime the thing. An electric pump under the tank pushes fuel to the carb no matter what, so problem solved and no more attempting to burn out your starter motor while 'cranking for gas'.

What happens when your mechanical pump sharts a diaphragm? That's right, instant oil contamination. Guess what? Electric pumps don't do that, so you can stop worrying about changing your oil if the pump goes bad. You can also stop worrying about destroying engine bearings if you ran with contaminated oil without knowing it. 'Nother reliability point in favor of electric.

Noise: if you don't like the solenoid style clacking pumps, Carter makes a quiet rotary pump suitable for carb applications for around the same price.

I really don't understand all the aversion to electric pumps when the benefits are so obvious. The only possible reason is maintaining a stock appearance, but those of use who have daily driven (torture tested) our Corvairs know that it is unacceptable to have that mechanical pump back there as a potential issue. Get rid of it, and get piece of mind. Get rid of the distributor while you're at it.
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Re: Electric Fuel Pump Installations

Post by davemotohead »

Well I keep a mechanical pump for a back up on the road,these pump bypass plates let you use the stock fuel lines and keep the stock look/lines in use and if the electric ever fails you can stick the mechanical in easy till you can replace the electric! BUT I have not had a facet Pump fail yet! and I have one with over 200,000 miles on it with 2 different engines, I have not bought into the EFI yet as I like the stock distributor with a pertronix,,Oh ya I know,,they suck,but the first 1 I ever bought is still running strong and if it ain't broke I am not fixing it! I still get 3rd gear posi rubber so good enough for me! I will be running a HEI on the next vair and will be good enough,I am not into the computor crap and think there is something to be said for Old school Know how! :tu:
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Re: Electric Fuel Pump Installations

Post by cilynx »

For folks getting here from google years later, the Facet pump above with the dead followup link is a 40105. It's self-priming, self regulating, and pushes 4.5 PSI. You can see the numbers etched in the flange in the first picture -- 40 on the left of the bolt hole and 105 on the right.

Related, does anyone make a SPDT pressure switch that fits the existing tap? I'd love to have a single switch with C going to ground, L1 (no pressure / engine off) going to the oil trouble light ground and L2 (pressure / engine running) going to the Facet fuel pump ground. If not, I can always T the tap and run both a stock negative pressure switch as well as a Vega positive pressure switch to accomplish the same thing, but fewer parts would be better.
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Re: Electric Fuel Pump Installations

Post by bbodie52 »

:link: http://www.corvair.com/user-cgi/catalog ... IN&page=66
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Mr. Gasket 7872 - Mr. Gasket Fuel Pump Safety Switch
:link: http://www.jegs.com/i/Mr.+Gasket/720/7872/10002/-1
ImageImage

$20.99

Amazon.com
Mr. Gasket 7872 Fuel Pump Safety Switch
by Mr. Gasket
:link: http://www.amazon.com/dp/B00068OQ3S/?ta ... mtwv2e6w_b

Price: $17.46 & FREE Shipping on orders over $35.
  • Designed to ensure that the electric pump does not work unless the engine has oil pressure
  • Crafted from high quality material for long lasting durability
  • Prevents the pump from running in a situation where the motor may stall with the ignition on
  • Continues to provide power to the pump as long as there is oil pressure to keep the switch turned on
  • Installed with the pressure sending unit using a T fitting into the block
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Re: Electric Fuel Pump Installations

Post by cilynx »

Thanks Brad -- Can you confirm that S&P on the Vega switch disconnect once oil pressure comes up?

Googling around, I'm finding folks saying that to use the Vega switch, you run S to the solenoid (powered when cranking), I to the Ignition (powered when key is on), and P to (+) on the fuel pump. Being that you no longer have a line that is grounded when the engine is off, you have to either reverse your idiot light's polarity by disconnecting it from the 12V bus and grounding it under the dash or just don't connect the idiot light in the back and don't have it at all.

It makes more sense to me that you should connect the stock idiot light wire to S, (-) on the fuel pump to I, and P to ground. This way, if it really is a SPDT switch, the idiot light will be properly grounded when the oil pressure is low and disconnected when it is high and the fuel pump will be properly grounded when the oil pressure is up and disconnected when it is low.

The only hangup I can think of is that some fuel pumps might have their cases grounded even though they have a dedicated ground wire. In this scenario, a rubber isolation mount and some grommets seem like a reasonable solution to block the ground path through the chassis. Give the noise fuel pumps make and the amplification there-of when fixed directly to a hard surface, an isolation mount probably isn't a bad idea anyway.

Thoughts?
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Re: Electric Fuel Pump Installations

Post by Nickshu »

I have seen some discussion about wiring the fuel pump thru the tach instead of using the oil pressure switch. Anyone try this or know where to tap in?
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Re: Electric Fuel Pump Installations

Post by bbodie52 »

The tachometer receives its power from the same circuit that provides 12 VDC to the Corsa GEN/FAN and TEMP/PRES warning light circuits, the fuel gauge, and the cylinder head temperature gauge. On the Monza and 500, which lacks the tachometer and cylinder head temperature gauges, switched power is provided to only the fuel gauge and warning lights. In both the Corsa and Monza/500, this switched power originates at the ignition switch.

It is not possible to tap power from this circuit to power the electric fuel pump circuit, since power would be available whenever the ignition key is in the ON position. The goal is to provide power to the fuel pump only when the engine is being cranked (for starting) and when the engine is running. That is the purpose of the safety switch that is triggered by the presence of oil pressure. The safety switch allows power to be fed to the electric fuel pump from the starter solenoid (when the starter is cranking the engine), and through the safety switch when oil pressure is present.

The Corsa tachometer sensor wire from the distributor does not provide power to the tachometer. It only senses (counts) switching activity from the ignition points or ignition trigger circuit that grounds the negative coil terminal to energize and release high voltage from the ignition coil.
1965-1969 Corvair - Instrument Cluster and Body Harness (CORRECTED)
1965-1969 Corvair - Instrument Cluster and Body Harness (CORRECTED)
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Re: Electric Fuel Pump Installations

Post by cilynx »

Since it doesn't seem there's a solid answer, I went ahead and ordered the Vega switch. I figure it's worth $20 to find out for sure.

Here's the circuit I'm going to test once I get the Vega switch:
Oil-Pressure-Switch-Circuit-Vega.png
Oil-Pressure-Switch-Circuit-Vega.png (12.16 KiB) Viewed 7311 times
Here's what my pressure switched circuit looks like right now:
Oil-Pressure-Switch-Circuit-Relay.png
Oil-Pressure-Switch-Circuit-Relay.png (14.27 KiB) Viewed 7311 times
I'm hoping the Vega switch is SPDT so I can get rid of the relay and its accompanying wiring.
Last edited by cilynx on Sun Jul 05, 2015 7:34 pm, edited 2 times in total.
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Re: Electric Fuel Pump Installations

Post by bbodie52 »

The instructions and diagrams below show how the Mr. Gasket safety switch would work. 12 VDC enters the safety switch from two sources: (1) The starter solenoid terminal labeled "R" (also connected to the ignition coil + terminal), and (2) The ignition switch when in the ON position.

The wire from the starter solenoid is connected to the "S" terminal on the safety switch. Internally, this connection is always tied to the "P" (Pump) terminal, wish provides power to the fuel pump. In this way, whenever the starter motor is engaged to crank the engine, power would also be fed to the fuel pump (so that the fuel line is pressurized when cranking the engine). At the same time, power from the ignition switch output is also connected to the "I"terminal on the safety switch, so that power is applied to the safety switch whenever the key is in the ON position. HOWEVER, the safety switch will NOT permit the power from the ignition switch to pass through ot the fuel pump until oil pressure reaches the safety switch.

With this arrangement, power is fed to the fuel pump ONLY when the engine is being cranked, or when the engine is running and producing oil pressure. If the engine stalls, oil pressure would drop off, which would shut off the electric fuel pump.
Fuel Pump Safety Switch.jpg
Brad Bodie
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Re: Electric Fuel Pump Installations

Post by cilynx »

The part I keep finding different answers on is whether or not S&P disconnect when oil pressure is up. If they don't disconnect, then there would have to be a diode inside so that power cannot flow from P to S when P is receiving power from I, otherwise the power that is supposed to be powering the fuel pump would also energize the starting circuit. Once I have the switch in-hand, I'll post resistance in both direction between all three terminals in both switch positions and will also report if my first circuit above actually works.
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Re: Electric Fuel Pump Installations

Post by bbodie52 »

The design of the starter solenoid itself does not permit power to reverse through the solenoid in any way. That same ignition wire is also tied to the ignition coil positive terminal. The coil receives a reduced voltage when the key is ON (via the ballast resistor wire), and it receives a full 12 volts when the starter solenoid is energized. This same feature is utilized by the fuel pump safety switch to pass through 12 VDC to the fuel pump when the starter solenoid is engaged, to provide the pump with power when the engine is being cranked. The power source from the solenoid is always connected to the fuel pump, but it has no voltage applied from the solenoid unless the key is turned to START.

The safety switch may act as a toggle switch. "S" and "P" may be connected in the absence of oil pressure, and "I" and "P" would be connected when oil pressure is present. This would prevent voltage from reaching the "S" terminal from the"I" terminal, since only one or the other would be tied to the "P" terminal at any given time, depending on the presence or absence of oil pressure.

Power from the source (starter solenoid) is switched off by the solenoid itself as soon as the driver releases the key to stop cranking the engine. The solenoid can only be actuated when voltage is applied to the "S" terminal from the ignition switch. The design of the solenoid does not permit it to be energized if voltage is applied to the "R" terminal, which is only there to feed the ignition coil (and in this case, the fuel pump) when the engine is being cranked by the driver.

Because of the presence of carburetors with float bowls, instead of fuel injection, I would guess that the presence of a fuel reservoir in each carburetor makes energizing the fuel pump during engine cranking somewhat unimportant, since there would normally be fuel present in the float bowls to allow the engine to start when it is cranked. The exception would be when the carburetors were empty, as the would be after a carburetor rebuild or if the engine sat long enough for the fuel to evaporate from the float bowls.
Starter Solenoid Internal Electrical Connections.jpg
Starter.jpg
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Re: Electric Fuel Pump Installations

Post by 66vairguy »

I'm one of the folks who gave up on mechanical fuel pumps.

Based on comments from folks on the Corvair forums the mechanical pumps from Airtex were well regarded at first, then the check valves were not staked properly and would drop out. Airtex supposedly fixed this, but a lot of bad pumps remained on the parts shelves causing buyers aggravation. Then it was discovered the Airtex pumps were producing around 9PSI and should be 4-5PSI. Many found dismantling the pump and cutting a coil off the spring would fix it - still aggravating. This problem is still reported on forums.

The main issue with the electric fuel pumps is purchasing a pump not rated for the Corvairs fuel pressure of 4-5PSI. A couple of years ago folks reported that a vendor was selling a 9PSI Airtex fuel pump that caused problems. Airtex only makes ONE electric pump compatible with the Corvair's specified fuel pressure -- model # E8016S that works on the Corvair. Fortunately it is used on a number of other vehicles and is not hard to find. Well regarded Steve Goodman of Rear Engine Specialists in Colorado recomends the Airtex # E8016S
Dave (Motohead) and others have had good experiences with the Facet pump, but I didn't see a part number listed here - BEWARE Facet makes a number of similar looking pumps in different pressure ratings.

AN EXPLANATION FOR THE PRESSURE RATING CONFUSION: The Airtex E8016S is rated at 2-4.5PSI - so folks think "Gee 2PSI is too low". NO, the rating is 2PSI at MAXIMUM flow rating - something you will NEVER see happen on a Corvair once the carburetors fill up. You'll always see 4.5PSI as soon as the carburetors fill up, even at WOT on the four carburetor engine. The common mistake is to use the Airtex pump rated at 5-9PSI which of course means the carburetors see 9PSI which is too high and causes flooding and rich run conditions and a lot of frustration to owners.

I hope this helps those considering an electric fuel pump.
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