gcarpenter

I just installed an Edelbrock 750 cfm carb and it stumbles under heavey load. It appears to be starving for fuel. I replaced the fuel pump a few months ago after it did the same thing with the old carb (also an Edelbrock 750) and now the problem is back. Is the stock fuel pump on my small block 350 enough to feed this carb? Do I need to upgrade? If so, what is a good pump? I have noticed that high flow pumps only have an inlet and an outlet. The stock pump has a third port (pipe). What's it for and do I need it? Thanks for any help!

FKING1

Try bigger jets.
Worked on my Holley with a stumble.

doctorgene

The third hole, is the return line to tank, I run without it, GM installed it to stop Vapor lock problems is my understanding, I'm sure you will get a lot of answers. I installed electric holly pump & don't think it will Vapor lock. There are a lot of smarter guys on here that can tell you what's right. Have a great one. Gene

Grumpy 427

Fuel delivery has been an issue for a long time.As long as the pump can supply the volume of fuel that the engine requires, the rest is in tuning. My Eddy carb suffered from an off idle stumble, played with the metering rods and squirters and seem to have it sorted out. i had issue with the float level, and fuel dripping out of the boosters at idle and flooding. Took the top of the carp off and went through it. Very easy carbs to work on. they have good tech support too.

I have an Eddy 110 mechanical pump and a brand new 3/8 fuel line with no return line. Used to run that setup on some of my mild BBC engines in my old camaro with out issue.

jcbass7

I had a fuel problem as well, but the answer turned out to be very simple. The rubber fuel hose connected between the fuel pump and the steel line coming from the tank was kinked. Previous owner messed with the set up enough that it kinked the line and wasn't allowing enough fuel to flow. He put a hose clamp right on the kink to open the line up a bit by squeezing it, but I discovered the problem when this clamp came loose and moved allowing it to kink again.

capevettes

If it's doing the same thing at higher RPM's even after the carb change I would be suspicious of the distributor and or tuneup/electrical issues.