Sam Barrett

If left setting over 3 days, I must prime the carberator to start the engine. It is a 1972 350 with a Quarajet.

Is this most likely a check valve in the fuel pump or in the carberator itself?

Erinyes

Are you certain there is no fuel in the bowl?

First thing I'd look at is the accelerator pump seal. If there is fuel in the bowl, but moving the throttle does not produce a twin squirt of fuel, it can be quite difficult to fire it up if it's been sitting any length of time.

An easy way to test it with the engine running is to let it idle, then use a screwdriver or something to depress the rod directly, without moving the throttle. The engine should die.

If it does not, rebuild it - kit and float, unless it is brass with no leaks.

zed

Common problem with Qjets.Fuel slowly leaks thru the cast plugs in the float chamber. Some coat them with epoxy when rebuilding to stop the leaking.

Olds64

Zed is correct. You can coat the jet plugs on the bottom of the fuel bowl with epoxy to prevent them from leaking. This is a common problem with Q-jets.

Erinyes

Leaking plugs is a common problem, true, but checking the accelerator pump takes about ten seconds. It's still the first place I'd look. If the pump is shot, rebuilding is needed anyway, at which point coating the plugs is a no-brainer.

I'm still curious as to whether Sam has definitively determined the bowl is empty.

Sam Barrett

Yes the bowl is empty. So I must have a leak in the bowl. I am going to rebuild and I will let you all know the reults. Also, I am going to replace the fuel pump as well.

I just found out that the check valve for the fuel pump is in the fuel filter.

Olds64

Well, since you need to disassemble the carburetor to coat the bottom of the fuel bowl with epoxy you might as well rebuild it while you are at it.

Sam Barrett

I have the rebuild kit and JB quick weld on my work bench.

Thanks for all of the help.