Occasional fuel supply issue..

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Cheryl&Joan
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Joined: Wed May 24, 2017 6:15 pm

Occasional fuel supply issue..

Post by Cheryl&Joan »

Hello, new to the site and Corvairs. We have a 65 Monza automatic with 12,000 miles.Looking for some advice/help.

The car ran great when we bought it last month. It started to smell like gas, I checked the engine compartment and it was spitting fuel out of the fuel pump. I replaced it. We drove the car for about 15-20 mins, it ran great. Then, all of the sudden it stopped running. It would not start. The next day I tried starting fluid...it started after a few tries. It ran great again, then stopped running again (then we waited a day and started it with starting fluid again) Now it runs great. But of course we are hesitant to drive it anywhere.

Based on discussion with mechanics and links on the forum this is what I've tried so far.
Opened the fuel lines at the carbs and cranked the motor, it's pumping gas fine to both carbs.
Made sure the new fuel pump was seated properly.
No visible/noticeable leaks in the fuel supply

My thoughts....
It seems to happen when the engine is hot.
Vapor lock?
It also happens when my wife is driving, she was worried about the car, so she was barely accelerating.
I have read that the carbs get so hot that they boil the gas...After it stalled i pulled the air cleaner and looked in the carb, I moved the throttle linkage, it shot a stream of gas into the carb...I was surprised to see how hot it was. It seems to steam and evaporate.
I did see a few posts about the carbs getting too hot.Do I need to buy new carb gaskets?

Appreciate any help!!

Thanks Jeff and Cheryl
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toytron
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Re: Occasional fuel supply issue..

Post by toytron »

Jeff and Cheryl, I am sure the first questions that people will ask is: tell us about yourselves, where are you located? What type of mechanical background do you have? Are you a member of a corvair club?
The reason for the questions and there may be more is to be able to best help you. If we know what state you live in then someone can suggest a local chapter and possibly someone who may be local to you who could stop by and lend a hand.
How mechanical will allow us to know how to word things to help online.
Yes there are many and especially some who are a tremendous help and knowledgeable. So share some more info and they will be along shortly. I am sure Brad will be along and I would like to pass along a recognition to him and others here "Thank you for your service to this country" and this forum.

Ed Stevenson

Edwin Stevenson
Industrial Electrician
Electronics Technician
65 corvair corsa convertible turbo
65 corvair monza
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bbodie52
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Re: Occasional fuel supply issue..

Post by bbodie52 »

:wave: :welcome2: Welcome to the Corvair Forum!
Jeff and Cheryl wrote:The car ran great when we bought it last month. It started to smell like gas, I checked the engine compartment and it was spitting fuel out of the fuel pump. I replaced it. We drove the car for about 15-20 mins, it ran great. Then, all of the sudden it stopped running. It would not start. The next day I tried starting fluid...it started after a few tries. It ran great again, then stopped running again (then we waited a day and started it with starting fluid again) Now it runs great. But of course we are hesitant to drive it anywhere.

Based on discussion with mechanics and links on the forum this is what I've tried so far.
Opened the fuel lines at the carbs and cranked the motor, it's pumping gas fine to both carbs.
Made sure the new fuel pump was seated properly.
No visible/noticeable leaks in the fuel supply
Based on your comments, it sounds like you have already been reading through earlier posts on the Corvair Forum as a part of your effort to troubleshoot your problem. I posted some of that information below in a discussion about your new fuel pump. Fuel starvation could be an issue with your car, if an air leak is present at any point between the fuel tank and the fuel pump. Using the information below, I would recommend that you test your new fuel pump for both fuel pressure and fuel delivery volume. If problems with fuel volume appears to be a possibility, you should check the condition of the fuel feed line between the fuel tank and the fuel pump, and pay particular attention to the condition of the short rubber fuel hoses in that line.

Although vapor lock would be something to consider, the carburetors have not been removed so it is unlikely that the gaskets and insulators at the base of the carburetors have been disturbed. If the steel feedline into the fuel pump has come into contact with a hot metal surface as a part of the pump replacement work, under hot conditions that steel line might become overheated and allow fuel to vaporize within the line during periods when the fuel is stagnant and not moving within the line. (When the carburetor float bowls are full, the needle valve in each carburetor closes to prevent further fuel from entering the carburetor float bowl. When this occurs the fuel pump automatically goes into an idle mode so that it does not try to pump more fuel to the carburetors. During these idle periods the fuel in the steel feedline that delivers gasoline from the tank to the fuel pump is not moving. Under these conditions the temperature of the gasoline in that line can begin to climb — particularly if the steel fuel line is touching an adjacent hot engine component. Under these conditions vapor lock is a possibility. In fact, Chevrolet added a fuel return line to the fitting at the fuel pump outlet that allowed gasoline to be circulated back to the fuel tank during periods when the carburetor float bowls were full. Introduced by Chevrolet engineers to the Corvair in 1968, this fuel return line was specifically added to help prevent vapor lock conditions from forming by allowing fuel to circulate continuously in a loop back to the tank when delivery to the carburetors was not needed. The continuously moving gasoline would help to cool the line and prevents vapor lock from occurring). So I would check the position of that line to make sure that it does not been shifted during the time it was detached from the original fuel pump and reattached to the new fuel pump.

You should also not exclude the possibility of an ignition system issue that could have developed. Is your distributor configured with the original points and condenser or has it been upgraded to a breakerless electronic ignition system? Also, does your ignition coil seem to be getting excessively warm? You have had several instances where your engine has stopped while driving. The ignition coil is mounted directly on the right cylinder head, which can transfer heat to the coil. Also if the engine stalls and you leave the key in the ON position for a length of time, there is a possibility of the coil overheating if the points happen to be closed when the engine stops. With the points closed the negative terminal of the coil is grounded. If the key happens to be left on, electrical current could be continuously flowing through the coil windings. This current flow can cause a heat buildup within the coil. I've even heard of the coil bursting and developing a leak under such conditions. Internal damage of the coil windings could also be a possibility under such circumstances. Early Pertronix I Ignitor electronic ignition modules could also be damaged if the key is left on for long periods of time. It is important to always turn the key off and not leave it in the ON position when the engine is not running. If internal damage to the ignition coil might be a possibility, it could be breaking down and failing as it gets hot. If you suspect such a possibility you may have to consider replacing the ignition coil is a part of your fault isolation and troubleshooting efforts. If you have a dwell tachometer and timing light, checking the settings in your ignition system might be a good idea just to confirm that everything is in good condition.

I usually recommend relocating the ignition coil by removing it from its factory mounting point on the right cylinder head and relocating it to a place on the perimeter frame at the back of the engine compartment, at a location that is near the distributor so that the main ignition wire between the coil and the center of the distributor cap can still reach between the two components. This will also allow the primary wire between the distributor and the coil negative terminal to reach. Relocating the coil away from the engine cylinder head helps it to run cooler, as heat from the cylinder head will no longer be conducted by the mounting bracket to the ignition coil housing.
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bbodie52 wrote: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.

A new fuel pump should always be tested for output pressure. If the pressure is found to be excessive it may be possible to cut the spring or to exchange the spring from the old pump and fit it into the new pump. This may correct the output pressure. It is also possible to purchase an aftermarket fuel pressure regulator such as the one shown below.

Here is a link for ordering the recommended Holley fuel pressure regulator...

:link: http://www.jegs.com/i/Holley/510/12-804 ... 1797507184

Holley 12-804 - Holley Fuel Pressure Regulators — $30.41
ImageImage

Holley#510-12-804

Standard Pressure Regulator
Chrome Finish
For use with gasoline
Port Size: 3/8'' NPT Inlet/Outlet
1 to 4 PSI
Includes Mounting Bracket

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 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! :doh:
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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.

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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.

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:chevy:

The link below will provide you with a list of useful websites that are Corvair-related. Some of the links will lead you to an extensive technical library that will allow you to download shop manuals and other technical references in Adobe Reader format at no cost. There is also a link that will help you to locate nearby CORSA (Corvair Society of America) club chapters. While the Corvair Forum can be very helpful as you work on your Corvair, having local friends and contacts in your region who are knowledgeable about the Corvair can also be very helpful. These family-friendly CORSA chapters often offer picnics, group scenic drives, technical training and assistance, car shows, and competition events that can greatly enhance your enjoyment of Corvair ownership. You will also find a list of essential Corvair parts suppliers. Clark's Corvair Parts is the biggest and oldest Corvair supplier in the world. You will find a link that can provide you with a series of videos that amount to a tour of the Clark's Corvair Parts facilities. I think you will be amazed at the quality of the reproduction components they offer — particularly the interior carpeting and re-upholstery items. Parts suppliers such as this truly make our Corvair hobby possible.

Common and Useful Corvair Websites

:link: http://www.corvairforum.com/forum/viewt ... 225&t=6007

:dontknow: I would like to encourage you to expand on your initial post and tell us more about yourself, your Corvair, and your goals for the Corvair. If you can describe your personal assessment of your mechanical skills and abilities, that would help a lot. Members of the Corvair Forum love to be helpful in assisting other Corvair owners with technical support and advice, but it helps a lot if we have some understanding of your technical background and mechanical abilities, Corvair-related knowledge, etc. Helping us to know more about you will help us to write comments to you that are tailored to your needs and experience. Knowing your location is also useful, because knowing where you live can sometimes suggest possibilities.

:welcome:
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
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Cheryl&Joan
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Joined: Wed May 24, 2017 6:15 pm

Re: Occasional fuel supply issue..

Post by Cheryl&Joan »

Brad, thank you thank you! I have really been enjoying the car and the community. After reading your reply and talking to a few others, I tried a number of things. I finally found the problem...it was my fault. I did not push the fuel pump in far enough. I loosened the set screw, pushed it down, and then screwed the set screw in....this time in went in much further. So the pump must have been partially pumping gas, then eventually starving the motor.

I like Cheryl's car so much, I'm considering getting my own! I really like your Blue color with the white letter tires.

Thanks, Jeff
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Cheryl&Joan
Posts: 14
Joined: Wed May 24, 2017 6:15 pm

Re: Occasional fuel supply issue..

Post by Cheryl&Joan »

Ed, Thanks for the reply.
Cheryl has always loved Corvairs. I didn't know too much about them, then one popped up for sale right here in South eastern Michigan. It was exactly what we were looking for. Really nice shape, and a smooth driver.

I'm a decent mechanic...although primarily with motorcycles, bikes and other things. Not necessarily cars, but I can figure thing out and have the equipment.

Our goal for the car is to enjoy it and drive it frequently on nice days (not a commuter).

We would also like to attend a few Corvair meets.

Thanks, Jeff
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bbodie52
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Re: Occasional fuel supply issue..

Post by bbodie52 »

Jeff wrote:I finally found the problem...it was my fault. I did not push the fuel pump in far enough. I loosened the set screw, pushed it down, and then screwed the set screw in....this time in went in much further. So the pump must have been partially pumping gas, then eventually starving the motor...

....We would also like to attend a few Corvair meets.
It makes my day when I make a suggestion that actually helps and leads to a solution of a problem! ::-):

The Detroit Area Corvair Club is hopefully close to your location in southeast Michigan. They have regular meetings and a big event coming up in August that you might enjoy. CORSA club chapters are family-friendly and offer things like technical training and assistance, car shows, competition events, picnics, scenic drives, etc. You might want to check out their websites and perhaps join them...


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Detroit Area Corvair Club - DACC — 5498 Duffield Road, Swartz Creek, MI, :link: http://detroitcorvairs.com
Email: clubinfo@detroitcorvairs.com

FACEBOOK :link: https://www.facebook.com/DETROITCORVAIRS
In 1970, Corvair enthusiasts established a social club: CORSA, Corvair Society of America, Inc. Currently there are approximately 6000 members. This is an international organization of Corvair owners and enthusiasts with 134 chapter clubs across the U.S., Canada, France and Switzerland. The DACC, Detroit Area Corvair Club, has approximately 150 members.

REGULAR MEETING NIGHT

DACC meets on the first Monday of every month.

Come and join us for our monthly meeting at the
Pontiac-Waterford Elks Lodge
2100 Scott Lake Road, Waterford
Meeting starts at 7pm. Come early for dinner.
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
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