Check valve in fuel line

[Jeff Y.]

I disconnected the fuel line from the carb and connected a pressure gauge. When I crank the car the pressure goes from 5 to 0, 5 to 0, etc. I'm having trouble with the carb staying full with fuel. So I was thinking I had a fuel pressure problem. Should there be a check valve in the pump to keep positive pressure?

This is a new rebuild, engine, carb, etc. '72 454 with a stock quad and fuel pump. The car ran great when I started it for the first time but slowly started to not want to run. I thought it was a vapor lock issues at first but now I'm having the trouble when cold.

Before I started the car today, I took the air clearner off and cycled the throttle and there was no spray of gas into the carb.

Disconnected the coil wire, cranked the engine for about 5 to 7 sec to get fuel to the car and still no spray when pumped. Started the car but would not stay running.

I'm thinking I have a bad fuel pump. It's a new rebuilt pump. Any thoughts?

[Edward J.]

Re: Check valve in fuel line

Jeff, do you have 5psi when cranking engine over( should have steady PSI when cranking), and when sitting it slowly goes to 0? This normal,There is no check valve in-line with the supply line.Have you checked the fuel filter to see if clogged?

If you take the fuel line off at Carb. and install a rubber hose over line and use a clear plastic container and turn car over and watch the fuel being pumped this will tell just how much fuel is being pumped. sometimes you can get PSI but not the volume needed.

[Jeff Y.]

Re: Check valve in fuel line

No as i crank the gauge goes from 5 to 0. Never stays at 5. This is why I think I have a bad pump.

[Kurt G.]

Re: Check valve in fuel line

Sounds like its time for a pump. The pump diaphragm should hold the pressure steady as well as keep the carb bowl filled for severAl hours after you shut down.

[Jeff Y.]

Re: Check valve in fuel line

I changed the pump yesterday and have the same problem. I'm thinking the carb float must be the problem. I'm going to disconnect the fuel line and see how much fuel is being pumped and if that is good the carb is coming off. The carb is a rebuild from one of the big box corvette stores. My guess is something in the float and valve is stuck closed. Don't know what else to look at.