Air in lines

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MiddleAgeMan
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Air in lines

Post by MiddleAgeMan »

Sorry this might sound like a real basic question... I change the hoses going in and out on the fuel tank but I stop in the middle of the job for a month. Now its all done. Can't get it to start. I think there's air in the fuels lines. Is there a trick to get the gas to the carburetor?

Its a 63 900 monza spyder
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terribleted
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Re: Air in lines

Post by terribleted »

No trick, but sometimes priming the carbs with a little fuel to get an initial start helps. Just remove the air cleaners and dump a tablespoon or so of gas down each carb and try to start. If it fires off and then dies more than a couple times check for actual fuel flow by cranking the engine over with a fuel line removed and a catch can and the ignition disabled (remove the ignition feed wire from the + side of the coil so as not to make ignition sparks when it is possible you might spill a little raw gas.). If no gas coming out then the is a blockage in the fuel lines or sender, or the pump is not working.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia
MiddleAgeMan
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Re: Air in lines

Post by MiddleAgeMan »

Perfect thanks
dave t
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Re: Air in lines

Post by dave t »

If you find a blockage in the body line, disconnect both ends and blow air through it. Spray some brake cleaner or carb cleaner in the line and blow through again. Have someone hold a rag on the other end and see what comes out. Keep spraying and blowing until you get good clean pressure coming out. Reconnect the hoses and try to start.

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bbodie52
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Re: Air in lines

Post by bbodie52 »

:wave: :welcome2: Welcome to the Corvair Forum!

With regard to the new problem you seem to be having with getting the Corvair started, if it was running reliably before but refuses to start now, you have to ask yourself: what has changed? The first illustration below shows the location of two short rubber fuel hoses that are part of the long fuel line that connects the fuel tank to the fuel pump. Most of that line is a solid steel line. Is there anything that you did that might've caused damage to that steel line? Or did you simply replace the two rubber hoses and hose clamps at each end of it?

The mechanical fuel pump in the Corvair must create a vacuum to pull the gasoline from the fuel tank the entire length of the car to the engine at the rear. It is something like sucking on a straw. The mechanical fuel pump does a pretty good job at this, but if there is an air leak anywhere between the fuel tank outlet and the fuel pump inlet, the mechanical fuel pump will not be able to pull the fuel into the pump. Since you stated that you replaced these two hoses, and you are now having difficulty getting the engine started, there is a possibility that the new hoses may not be tightly sealing and may possibly be permitting air to leak into the fuel line. Since this long line is not under pressure, a poor connection may not be obvious since no fuel would be observed dripping from the line. But an air leak in the line could potentially prevent the necessary vacuum from being formed by the mechanical fuel pump — making it impossible for fuel to reach the pump so that it can be pressurized and delivered to the carburetors.

I would recommend that you disconnect the pressurized steel fuel line at the carburetor inlet and perform a fuel volume test as outlined in the shop manual section shown below. The fuel pump should be the able to deliver at least 1 pint of fuel in 40 seconds or less while the engine is being cranked. If no fuel is coming out of the fuel pump while cranking the engine, I would be suspicious of the new hoses that you installed recently, and would recommend rechecking the hoses and hose clamps to ensure a tight seal.

Did you perform any other work other than replacing the fuel line hoses?
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.

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.

ImageImageImage

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
MiddleAgeMan
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Re: Air in lines

Post by MiddleAgeMan »

Thanks for all the help. I did get it started but now I have a new issue. When I replaced the hoses on the gas tank I only replaced the rubber hose to the metal fuel line and larger hose that leads to the gas cap. When I dropped the gas tank to replace those hoses I didn't remove the third above the large inlet. Its hard for me to see but with my hands it seems that its broken right at the red mark on the image below. Does that mean I'm replacing the gas tank or is that a replaceable piece?
Image
MiddleAgeMan
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Re: Air in lines

Post by MiddleAgeMan »

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terribleted
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Re: Air in lines

Post by terribleted »

Your photos did not post. The fuel tank should have 3 hoses that attach to it, but, since it is a turbo there is a 4th small hose connection in the filler neck area. The hoses on a non turbo are outlet at the bottom right of the tank where fuel flows out to the engine, the larger diameter hose that connects the filler neck to the tank and a smaller hose (over flow return) that connects from the filler neck to the top of the tank right next to the large diameter filler neck hose. This smaller hose is to allow overflow or splash in the filler neck to go into the tank. On your turbo car this hose is a special T shape. there is a small diameter short metal fuel line nipple(about 2" long) that connects from this T to the small diameter steel fuel return line coming forward from the fuel filter in the engine bay. It can cause a fuel leak if it is damaged when running the engine or fueling the car. If the metal pipe out of the tank that connects to this small hose is physically broken or rusted off then a new tank is the fix. (If this item is rusted much the tank internally is likely very bad so a new tank is likely needed anyway) If the hose nipple on the filler neck is broken replace the filler neck.

The short metal Joiner line, special T hose and all needed parts are available from Clark's Corvair along with the rest of any fuel system needs. These hoses at the neck are either very difficult or impossible to change with the tank in the car. If you have issues in this area I would recommend draining the tank, removing the fuel sending unit, and using a suitable flashlight and perhaps a small inspection mirror to see what the inside bottom of the tank looks like. IF it looks crusty and corroded at all I highly recommend replacing the tank and hoses. Nothing is more annoying than having the car refuse to operate over and over from debris and rust in the fuel system. Do it right once and never fool with it again:) If the tank looks gorgeous then remove the tank and replace the hoses and don't forget to buy new hose clamps as well as it makes the job a whole lot easier.

Here is a link to the relevant page of Clarks catalog showing the overflow T and associated parts http://www.corvair.com/user-cgi/catalog ... IN&page=54
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia
MiddleAgeMan
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Joined: Sat Jun 03, 2017 9:47 am

Re: Air in lines

Post by MiddleAgeMan »

Thank you again for the information. Let me go drop the tank and get this fixed
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