Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Difficult hot/wam restarts...Ethanol?
brown7373:
So you are saying to loosen to release the pressure, to see if that helps. If that does solve the problem, is there a permanent fix?
I did check the top of the carb after a hot shut down and saw zero vapor or evidence of leaking coming from the carb.
Cliff Ruggles:
A few posts back you mentioned giving it a shot of gas and it acted flooded.
This would indicate that there is already plenty of, if not too much fuel in the intake.
Since there are no indications of the bowl leaking down after sitting several days, and bottom plugs are sealed, unlikely it's leaking out the bottom of the carb anyplace.
To have a leak higher up in the casting the fuel level would need to rise after shutdown. This can be caused by a pressure size in the fuel line after the pump.
Another possible cause is a very slight leak at the gasket under the fuel inlet seat. This problem isn't all that common, but does produce the exact symptoms that you have. A very small leak doesn't effect the engine when it's running, provided the fuel being used by the engine is greater than the leak. It can cause a problem after shutdown if you still have pressure in the fuel line, or on an electric pump set-up if the pump is left on after shut-down......Cliff
brown7373:
I did have pressure in the line after shut down. I noticed that when I removed the carb, not immediately after shut down, but within a half hour or so. I am running a stock mechanical pump on a 1972 Olds Cutlass 350, but don't remember if it has a return line. Would a return line relive the pressure after shut down? Maybe I will remove the inlet seat and make sure nothing is causing a leak.
von:
I had that problem with my '69 Malibu and it was caused by a parts store replacement mech fuel pump having too much pressure. When running the carb could keep up but after shutdown pressure would rise and overcome the needle and seat, then flood and hard starting. Many of the off-brand parts store pumps nowadays are that way. A new AC Delco pump fixed it.
brown7373:
Hmmmm. Fuel pump pressure. I DID replace the fuel pump a while back. I think it is an Air-tex, which I never heard of. I see no evidence like vapor in the carb when I shut it off, but it doesn't restart like I think it should. This is on a 72 Cutlass 350 Q-jet.
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