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Discussion Starter #1
I did a search for this problem but did'nt really find the solution, I have a gas filter inline between the mech fuel pump and carb. When the car is shut down it immediatly starts to drain back to the pump until all fuel is out of the glass filter. Is there a check valve in the pump? (HOLLEY) if so are they replaceable? Is the pump rebuildable? It is a new pump, but I've had it for about for 6 yers just never used it. Thanks, Ron
 

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For some unexplained reason, transparent filters often have air in them, so it isn't necessarily a problem so long as your keeping the float bowls full under all conditions.

I suppose it might have to do with the fuel being under pressure while the engine is running and the vapors remain condensed. But when the engine shuts down and the pressure declines in conjunction with a hot motor, the vapors form.

If you have a automotive vacuum gauge, chances are it doubles as a fuel pressure gauge (low pressure that is). You could rig up a T to the last leg of the fuel line and measure the pressure. It should not exceed 5psi. I'd expect the pressure to decline slowly once the engine is shut down. If the pressure doesn't hold, you can disconnect the fuel inlet to the carb and plug the line. Then fire it up breifly (it'll die fairly soon without a fuel source), and see if the pressure holds better. If so, then the needle and seat in the carb are probably not sealing well and may be causing a rich condition as a result.
 

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Discussion Starter #4
I have a press. gauge on it , reads 5-6 PSI while engine running. Press bleeds off within 3-4 seconds after shut down. This engine starts immediatley when cold, set the choke and fast idle cam and it runs great, but after it gets to operating temp. and you shut off for a few minutes it needs to crank for about 10-15 seconds before it starts. The carb. (Edelbrock) just had new gaskets and needle and seats installed, it acts just like it did before, no change. I have the fuel filter about an inch off of the intake so I don't think? heat is the culprit. I'll do the disconnect fuel line and run and see if the press bleeds off.
Thanks, Ron
 

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Very possible that there is a small crack in the pump diaphragm. I had one of those Holley pumps with the clockable housing that I ran for a few minutes and then let it sit for seven years. It leaked the next time the car was run. I replaced with a Summit (ugly Holley) unit with clockable housing and it will hold pressure after shutdown for awhile. I can also leave the car for a week, give the gas a couple pumps, and it fires up with the first turn of the key. I've got a Holley Street Avenger carb though. I have a cheap transparent plastic filter before the pump and my fuel line at the carb has a brass filter.

It seems there should still be enough fuel in the bowls to get it to fire though. I don't know the differences between a Holley and Edelbrock carb.
 

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5 to 6 PSI is great. Not sure what to think about the leak rate. 3 to 4 seconds is plenty good enough to run, but I'm not sure if that's typical for those pumps.

I'd be curious about the carb. Getting one dialed in is an art and every vehicle has it's own personality. The choke is a significant factor. Somethimes a carb that is chokeless or has a choke that doesn't choke as much as it should can show great cold start behavior and then act sluggish when hot as a result of an over rich carb. To make matters worse, timing and carb setup interact such that one adjustment affects others.
 

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Discussion Starter #7
I disconnected the fuel line from the carb and plugged it. It started the same way, cranked for several seconds, then started, after about, I'd say a minute or there abouts, the engine died and the fuel in the filter drained right back to the pump. I think I'll try another pump, I have a couple in the barn but none have the right orentation for the fuel lines. I'll find one and change out the pump and see what happens, it's only a 15 minute job. Thanks again, Ron
 
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