Hello all,
My father passed away in August of last year from cancer. With his passing his 77 Corvette got passed down to me. It has been sitting for 9 years and is now having some issues. I did manage to get it running and driving but I'm having a issue with a couple things. First is a fuel delivery issue. The car has a 400 small block in it with a Holley electric mighty mini fuel pump mounted on the passanger side fender well this is how ever a new pump that I installed yesterday to replace the what I thought was faulty pump that was originally on the car. After a couple short runs with it it starts to run lean and I see that the fuel filter starts to run dry and the pump becomes obnoxiously loud. I pull off the fuel line feeding the pump and theres nothing then it starts to run out after a second or two then I hook it back up to the pump and nothing again the vent line is plugged. Now as a kid growing up this car would make a hissing sound out of now where. When I asked my dad what that was he said that it was the fumes in the gas tank being released. This car does not do this anymore so I'm wondering if this is the problem of if it is part of the problem. Any help is greatly appreciated thank you.

 

When the fuel filter starts to run dry, remove the gas cap and see if it clears up.
If it does, your problem may be in the charcoal canister and/or the plumbing to it.
These tubes and hoses run down the LH side of the frame and the canister is behind the LH front tire.
There are threads on the forum that deal with rebuilding this canister with charcoal for a fish aquarium.

If it doesn't clear up, your fuel supply pickup filter sock may be bad.
This sock is down in the bottom of the tank attached to the metal pickup tube.

Good luck with your project.

 

what happened to the mechanical pump.?
what do you mean the vent line is plugged?
the Holly web site states this pump should be within 50" of the tank.
if you a running a factory Quadrajet this pump puts out too much pressure without a regulator.
If you are using the 5/16" hose that is smaller than what the car originally came with, 3/8"
https://www.holley.com/products/fuel...s/parts/12-428

 

Electric pumps are made to push fuel not pull it to the front of the car. Relocate it to the rear of the car.

 

I missed that the electric pump was mounted up front.

 

It does not clear up when the fuel cap is loose or off. There was fuel that was in the car when I started working on It that sat in the tank a long time. Would that have maybe deteratied the sock that's in the tank?

 

I'm am not to sure to why the mechanical fuel pump is not on there. The vent line coming from the tank has a rubber cap over it. The carb is a Holley 650 1850-3 model number. The fuel pump I am using is a Holley 12-427 which is rated at 4 to 8 psi I believe.

 

12-427 is not any better should be within 12" of the pump not the front of the car, Quadrajet does not like 7 PSI, and the 5/16" line is too small. You should find out why the original factory mechanical pump is not there.
https://www.holley.com/products/fuel...s/parts/12-427

 

Like MelWff said, an electric pump has to be mounted near the tank, not near the engine.
You really should get rid of the electric pump and install a stock type AC Delco pump on the engine - less than $50 from Rock Auto. Get a stock, metal fuel line, from Corvette Central etc., to connect from the pump to the Qjet. Get MOLDED rubber fuel lines to connect the fuel lines to the fuel pump. Not sure what's there now but you want to use the stock return line, off the stock pump. Put a vented cap on your gas tank. I use this exact setup on my 77, with a 383, and it runs perfectly.