Airtex electric fuel pump woe.

[lostboy]

I have one of those airtex electric pumps for the better part of two years. I hear the pump coming on but it seems like it isn't pumping. Car runs, drives, chokes shuts off and then repeats. I got home from my 30 mile commute but it was not easy. Anyone experience the failure of these pumps? Do they still make noise but just don't provide any pressure? Or do they burn out completely. Thanks. This is frustrating. I have an extra pump that I'll probably end up trying.

Sent from my LG-H931 using Tapatalk

[Jerry Whitt]

Yes!!!! Have had the same problem. Went to Autozone and got one of their cheap units. Works fine.

[bbodie52]

I am always amazed how many Corvair owners are quick to blame the mechanical fuel pump on their Corvair for a fuel delivery failure. They often quickly dump the original pump and replace it with a more-expensive and more-complex electric fuel pump system, assuming that the electric pump (an electro-mechanical pump) will be more reliable. NOT NECESSARILY TRUE!

Actually, the stock Corvair pump is a relatively simple mechanical pump that has been proven for dozens of years in hundreds of thousands of Corvairs over millions of miles. A common weak link in the mechanical fuel pump is not in the pump itself, but instead is found in the long fuel line between the fuel tank and the pump...

The stock Corvair mechanical fuel pump has proven itself in performance and reliability for decades through millions of Corvairs. There is a tendency to quickly abandon it and go running to an electric fuel pump replacement at the first sign of apparent trouble. Old age can certainly be a drawback, or weakness with this pump, but many continue to survive. There was certainly a period of poor quality aftermarket replacement pumps, and rebuild kits are no longer available. But if you begin having what appears to be carburetor problems, don't be too quick to condemn the pump.

There are two relatively simple tests outlined in the Corvair shop manual. These tests measure output pressure and fuel delivery volume. The output pressure test utilizes a common vacuum/pressure gauge and is relatively inexpensive. The output pressure is regulated by an internal spring that is contained in the upper pump housing. Unless your pump springs a leak in one of the diaphragms or seals, it is likely that the output pressure will not change with age. However, new pumps may be fitted with a spring that produces an output pressure well in excess of the 4-5 psi standard. High-pressure can cause carburetor flooding, and is particularly a problem with the Carter YH found on turbocharged Corvairs.

The second test measures fuel flow at the fuel pump outlet. The standard in the shop manual states that the pump should be able to deliver 1 pint of fuel over a period of 40 seconds or less at engine cranking speed. If your pump does not appear to have any leaks and can pass the output pressure test, but fails to deliver the needed fuel volume, the problem may not be with the pump itself. There is a long fuel line that runs the length of the car from the fuel tank to the fuel pump. In order to pressurize and deliver fuel to the carburetors, the pump must be able to create a continuous vacuum in that fuel line to draw the fuel from the tank to the pump. Most of the fuel line is made up of steel tubing and is unlikely to develop a leak. However, there are two short lengths of rubber fuel hose in the fuel path. One section of hose is found at the fuel tank outlet, while the other is found adjacent to the starter motor — just before the line enters the engine compartment. The purpose of the second hose is to absorb vibration from the engine and prevent it from reaching the rigid steel fuel line. If either one of these two hoses develops a leak, the leak itself may not be apparent because the line is not under pressure so fuel will not be forced out. Instead, the leak amounts to a vacuum leak, which can allow air to enter the fuel line. This can prevent fuel from being drawn from the tank to the fuel pump, much like you might experience with a drinking straw if the straw was to split and developed an air leak in the side of the straw. What appears to be a faulty pump that is causing fuel starvation problems in the carburetors often turns out to be a leak in the fuel line at some point between the gas tank and the fuel pump. So if fuel starvation becomes a problem with your carburetors, there is a tendency to question the condition of the needle and seat valve inside the carburetor, or to blame the fuel filter at the carburetor inlet (thinking it is clogged), or to blame the fuel pump itself. Before you blame the pump and toss it, or abandon it and replace it with electric fuel pump, be sure to check the condition of the rubber fuel hoses at each end of the long fuel line between the fuel tank and the fuel pump. You may find that a couple of hose clamps and a few inches of replacement fuel hose is all that necessary to get you back on the road!



There is also a fuel tank strainer inside the gas tank on the outlet tube. It was listed as a part used in 1960-1965 Corvairs, but it could be installed on any model year. It is conceivable that this strainer could become plugged and could restrict fuel flow to the fuel pump.




Also, if you have any reason to remove and reinstall the fuel pump, be sure that you have installed it properly. I would confirm that the fuel pump is correctly seated and installed. There is a hole in the side of the pump shaft that the tapered bolt tip must seat into. If the pump is sitting too high and the bolt is simply pressing against the side of the pump housing, rather than seating inside the tapered hole, the pump push rod will not be doing its job. So first confirm proper pump installation, and then check the fuel pump output pressure and volume, as shown in the shop manual pages above. Fig. 57 in the shop manual page shows the tapered hole that the tip of the bolt fits into. This ensures proper installation and seating of the pump.

A new mechanical pump, push rod, and spring, adds up to $88.10. If the existing pump proves to be serviceable, it could be retained as an emergency spare and stored in the trunk, providing for an emergency roadside repair.

While installing/retaining an electric fuel pump may be a good option (depending on what you find in your existing system), it is a relatively expensive and complex change that may not be necessary. The factory design of the fuel and ignition systems in the Corvair has been proven to be reliable for decades of operation in many thousands of Corvairs. I would suggest carefully checking the basic system before jumping ahead and trying to resolve the problem with a modification that includes electric fuel pump and associated safety switches.

Part number C259: 62-69 FUEL PUMP ROD-REPRO (3 13/16") REBUILT FUEL PUMP 60-61=CX1617- ROD=C7256

Weight: 0 lbs 4 oz
Catalog Pages(s): 11(28),65
Price: $ 19.10

Part number C1604: FUEL PUMP SPRING

Weight: 0 lbs 2 oz
Catalog Pages(s): 11(34),65
Price: $ 3.45

Part number C3403: 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 $ 65.55
2+ $ 63.60

=======================================================================================================

Depending on what you have and what you need, here are some prices for some installation hardware and possibly for a replacement electric fuel pump. I have listed some Clark's prices and some prices from alternate vendors...

Part number C12879: FUEL PUMP BY PASS PLATE-STRAIGHT THROUGH WITH ELECTRIC PUMP

Weight: 0 lbs 8 oz
Catalog Pages(s): 66
Price: $ 47.25

Part number C9848: FUEL SAFETY INERTIA SWITCH

Weight: 1 lbs 0 oz
Catalog Pages(s): 66
Price: $ 83.35

(Pegasus Fuel Pump Shut-Off Switch - Inertia Activated, P/N: 1108 - $59.99)


Part number C5607X: SAFETY SHUT-OFF SWITCH WITH FITTINGS TO ALLOW USE OF STOCK OIL PRESSURE SWITCH TOO

Weight: 0 lbs 10 oz
Catalog Pages(s): 66
Price: $ 44.05

(Airtex OS75 - Airtex Oil Pressure Safety Switch - $14.97 or Carter Oil Pressure Safety Switch A68301 - $17.97) plus
Part number C7521: ADAPT-A-BOLT-STOCK FILTER* IF USING W/ OIL TEMP SENDER-NEED TO DRILL ADAPTOR DEEPER

Weight: 0 lbs 6 oz
Catalog Pages(s): 27D
Price: $ 24.90

SAFETY SHUT-OFF SWITCH WITH FITTINGS TO ALLOW USE OF STOCK OIL PRESSURE SWITCH TOO: $39.87

Airtex External Electric Fuel Pumps E8016S
$27.44
https://www.summitracing.com/parts/atx-e8016s


Facet Cube Style 12 Volt Fuel Pump, 3 to 4.5 max psi
Part No: FAC-40105
$48.99
https://www.pegasusautoracing.com/produ ... oCJ_jw_wcB

I have found the Corvair mechanical fuel pumps to be very reliable (I have yet to have one fail, and I have been around Corvairs since 1961). Since they are unique in design for Corvairs only, keeping a spare mechanical fuel pump in the trunk might be wise, since they are unlikely to be in stock at most auto parts stores and having a spare on-hand can make a relatively simple roadside repair possible.

The Airtex and Facet electric fuel pumps previously mentioned are also of high quality and highly reliable. They are electromechanical in nature and can still fail. The installation of an electric fuel pump adds some complexity to your fuel system, and pressurizes the fuel line all the way from the fuel tank to the engine compartment (electric fuel pumps are generally designed to be installed close to the fuel source, and do not function very well if they are installed a long distance from the fuel tank). A safety switch should be included in the installation so that electrical power to the fuel pump will be cut if the engine dies (switch triggered by engine oil pressure). A fuel filter at the electric fuel pump inlet is also a good idea.

[lostboy]

I am always amazed how many Corvair owners are quick to blame the mechanical fuel pump on their Corvair for a fuel delivery failure. They often quickly dump the original pump and replace it with a more-expensive and more-complex electric fuel pump system, assuming that the electric pump (an electro-mechanical pump) will be more reliable. NOT NECESSARILY TRUE!

Actually, the stock Corvair pump is a relatively simple mechanical pump that has been proven for dozens of years in hundreds of thousands of Corvairs over millions of miles. A common weak link in the mechanical fuel pump is not in the pump itself, but instead is found in the long fuel line between the fuel tank and the pump...

The stock Corvair mechanical fuel pump has proven itself in performance and reliability for decades through millions of Corvairs. There is a tendency to quickly abandon it and go running to an electric fuel pump replacement at the first sign of apparent trouble. Old age can certainly be a drawback, or weakness with this pump, but many continue to survive. There was certainly a period of poor quality aftermarket replacement pumps, and rebuild kits are no longer available. But if you begin having what appears to be carburetor problems, don't be too quick to condemn the pump.

There are two relatively simple tests outlined in the Corvair shop manual. These tests measure output pressure and fuel delivery volume. The output pressure test utilizes a common vacuum/pressure gauge and is relatively inexpensive. The output pressure is regulated by an internal spring that is contained in the upper pump housing. Unless your pump springs a leak in one of the diaphragms or seals, it is likely that the output pressure will not change with age. However, new pumps may be fitted with a spring that produces an output pressure well in excess of the 4-5 psi standard. High-pressure can cause carburetor flooding, and is particularly a problem with the Carter YH found on turbocharged Corvairs.

The second test measures fuel flow at the fuel pump outlet. The standard in the shop manual states that the pump should be able to deliver 1 pint of fuel over a period of 40 seconds or less at engine cranking speed. If your pump does not appear to have any leaks and can pass the output pressure test, but fails to deliver the needed fuel volume, the problem may not be with the pump itself. There is a long fuel line that runs the length of the car from the fuel tank to the fuel pump. In order to pressurize and deliver fuel to the carburetors, the pump must be able to create a continuous vacuum in that fuel line to draw the fuel from the tank to the pump. Most of the fuel line is made up of steel tubing and is unlikely to develop a leak. However, there are two short lengths of rubber fuel hose in the fuel path. One section of hose is found at the fuel tank outlet, while the other is found adjacent to the starter motor — just before the line enters the engine compartment. The purpose of the second hose is to absorb vibration from the engine and prevent it from reaching the rigid steel fuel line. If either one of these two hoses develops a leak, the leak itself may not be apparent because the line is not under pressure so fuel will not be forced out. Instead, the leak amounts to a vacuum leak, which can allow air to enter the fuel line. This can prevent fuel from being drawn from the tank to the fuel pump, much like you might experience with a drinking straw if the straw was to split and developed an air leak in the side of the straw. What appears to be a faulty pump that is causing fuel starvation problems in the carburetors often turns out to be a leak in the fuel line at some point between the gas tank and the fuel pump. So if fuel starvation becomes a problem with your carburetors, there is a tendency to question the condition of the needle and seat valve inside the carburetor, or to blame the fuel filter at the carburetor inlet (thinking it is clogged), or to blame the fuel pump itself. Before you blame the pump and toss it, or abandon it and replace it with electric fuel pump, be sure to check the condition of the rubber fuel hoses at each end of the long fuel line between the fuel tank and the fuel pump. You may find that a couple of hose clamps and a few inches of replacement fuel hose is all that necessary to get you back on the road!



There is also a fuel tank strainer inside the gas tank on the outlet tube. It was listed as a part used in 1960-1965 Corvairs, but it could be installed on any model year. It is conceivable that this strainer could become plugged and could restrict fuel flow to the fuel pump.




Also, if you have any reason to remove and reinstall the fuel pump, be sure that you have installed it properly. I would confirm that the fuel pump is correctly seated and installed. There is a hole in the side of the pump shaft that the tapered bolt tip must seat into. If the pump is sitting too high and the bolt is simply pressing against the side of the pump housing, rather than seating inside the tapered hole, the pump push rod will not be doing its job. So first confirm proper pump installation, and then check the fuel pump output pressure and volume, as shown in the shop manual pages above. Fig. 57 in the shop manual page shows the tapered hole that the tip of the bolt fits into. This ensures proper installation and seating of the pump.

A new mechanical pump, push rod, and spring, adds up to $88.10. If the existing pump proves to be serviceable, it could be retained as an emergency spare and stored in the trunk, providing for an emergency roadside repair.

While installing/retaining an electric fuel pump may be a good option (depending on what you find in your existing system), it is a relatively expensive and complex change that may not be necessary. The factory design of the fuel and ignition systems in the Corvair has been proven to be reliable for decades of operation in many thousands of Corvairs. I would suggest carefully checking the basic system before jumping ahead and trying to resolve the problem with a modification that includes electric fuel pump and associated safety switches.

Part number C259: 62-69 FUEL PUMP ROD-REPRO (3 13/16") REBUILT FUEL PUMP 60-61=CX1617- ROD=C7256

Weight: 0 lbs 4 oz
Catalog Pages(s): 11(28),65
Price: $ 19.10

Part number C1604: FUEL PUMP SPRING

Weight: 0 lbs 2 oz
Catalog Pages(s): 11(34),65
Price: $ 3.45

Part number C3403: 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 $ 65.55
2+ $ 63.60

=======================================================================================================

Depending on what you have and what you need, here are some prices for some installation hardware and possibly for a replacement electric fuel pump. I have listed some Clark's prices and some prices from alternate vendors...

Part number C12879: FUEL PUMP BY PASS PLATE-STRAIGHT THROUGH WITH ELECTRIC PUMP

Weight: 0 lbs 8 oz
Catalog Pages(s): 66
Price: $ 47.25

Part number C9848: FUEL SAFETY INERTIA SWITCH

Weight: 1 lbs 0 oz
Catalog Pages(s): 66
Price: $ 83.35

(Pegasus Fuel Pump Shut-Off Switch - Inertia Activated, P/N: 1108 - $59.99)


Part number C5607X: SAFETY SHUT-OFF SWITCH WITH FITTINGS TO ALLOW USE OF STOCK OIL PRESSURE SWITCH TOO

Weight: 0 lbs 10 oz
Catalog Pages(s): 66
Price: $ 44.05

(Airtex OS75 - Airtex Oil Pressure Safety Switch - $14.97 or Carter Oil Pressure Safety Switch A68301 - $17.97) plus
Part number C7521: ADAPT-A-BOLT-STOCK FILTER* IF USING W/ OIL TEMP SENDER-NEED TO DRILL ADAPTOR DEEPER

Weight: 0 lbs 6 oz
Catalog Pages(s): 27D
Price: $ 24.90

SAFETY SHUT-OFF SWITCH WITH FITTINGS TO ALLOW USE OF STOCK OIL PRESSURE SWITCH TOO: $39.87

Airtex External Electric Fuel Pumps E8016S
$27.44
https://www.summitracing.com/parts/atx-e8016s


Facet Cube Style 12 Volt Fuel Pump, 3 to 4.5 max psi
Part No: FAC-40105
$48.99
https://www.pegasusautoracing.com/produ ... oCJ_jw_wcB

I have found the Corvair mechanical fuel pumps to be very reliable (I have yet to have one fail, and I have been around Corvairs since 1961). Since they are unique in design for Corvairs only, keeping a spare mechanical fuel pump in the trunk might be wise, since they are unlikely to be in stock at most auto parts stores and having a spare on-hand can make a relatively simple roadside repair possible.

The Airtex and Facet electric fuel pumps previously mentioned are also of high quality and highly reliable. They are electromechanical in nature and can still fail. The installation of an electric fuel pump adds some complexity to your fuel system, and pressurizes the fuel line all the way from the fuel tank to the engine compartment (electric fuel pumps are generally designed to be installed close to the fuel source, and do not function very well if they are installed a long distance from the fuel tank). A safety switch should be included in the installation so that electrical power to the fuel pump will be cut if the engine dies (switch triggered by engine oil pressure). A fuel filter at the electric fuel pump inlet is also a good idea.

Yes. That's why I ordered one and a bunch of fittings for it from Clark's yesterday. I'm done with electric. My grandfather had a 61 and not only did that car sit for periods of time, but I'm almost positive it was the original unit and it worked peefectly and always.

Sent from my LG-H931 using Tapatalk

[66vairguy]

After DELCO stopped making the original mechanical aluminum fuel pumps the aftermarket pot metal units have had long history of problems. Documented in CORSA articles.

On the covaircenter forum the reported problems with mechanical fuel pumps far exceed problems with electric fuel pumps.

One of the greatest tragedies of life is the murder of a beautiful theory by a gang of brutal facts.
– Benjamin Franklin

[bbodie52]

Tips From CORVAIR UNDERGROUND...

http://www.corvairunderground.com/fuelpump.htm

Let's Talk About



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....



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.