Fuel drainage issue.

[Dibly74]

In my 79 Continental if it sits for a day or more the carb drains low enough to where the accelerator pump cant spray gas into the carb without turning it over a few times. The carb has been rebuilt twice and runs great when started. Does anybody have any idea what can make it drain that low from sitting, especially for that short of a time.

[Steve Moran]

I had a 79 F150 with a 460 and I had the same problem, never figured it out. sorry.
I finally replaced the carburetor with a newer one and the problem went away.
I tried 3 different Brands of kits and 2 different power valve styles.

[Dereck]

Hi Dibly74

I had two problems on my 79 Continental causing fuel drain back.

1. The power valve in the carburettor was open causing fuel to drain into the intake, made for easy starting :D

2. When I fixed the power valve I found I had a pin hole in the rubber fuel pipe as it comes out of the tank, it didn't actaully leak fuel but would allow the fuel to drain back.

Another possibility is a dodgey valve in the fuel pump.

Regards

Dereck

[Dibly74]

I've tried two different power valves and its still the same. My original power valve was the same as yours Dereck, the car could sit for a month and just tap the starter and it was running.

I was also thinking the fuel pump because it sat for somewhere around 5 or more years sometime before I bought it. Any kind of test I can do?

Also I found a new power valve in my closet. Should it move very freely or be tight. I've never heard what its supposed to be. My original one was hard to move but leaked causing to easy of starts and bad mileage. The one thats on the car was a little tense but moved by hand, and makes it hard to start after sitting. The one in my closet is very free. And what motion activates the power valve to do what it does? Accelerator pump pressure, vacuum...?

[Dibly74]

Well I replaced the power valve with the spare new one I had so I guess I will give it some time and try to start it.

[Dereck]

I was also thinking the fuel pump because it sat for somewhere around 5 or more years sometime before I bought it. Any kind of test I can do?

And what motion activates the power valve to do what it does? Accelerator pump pressure, vacuum...?

Hi Dibly74

The only tests I know of on a fuel pump are for fuel delivery pressure (about 7psi) and delivery rate.

The power valve is vacuum/spring operated.

Regards

Dereck

[Dibly74]

Well after letting the car sit for 2 days at a time and tring to start it, it held gas in the bowl. Pump the pedal twice and as soon as the starter engages it starts. Thanks for the input guys.