The Stovebolt Site Forums The Shop Area The HiPo Shop Fuel Pressure Drop-off

I wrote before on this topic and thought I solved the problem. Here is my engine setup:

I have a rebuilt Chevy 350. It has a slightly higher performance cam. I have a Edelbrock 1406 carb (electric choke) with a mechanical Holey fuel pump.

Symptoms:

I start the engine and it runs GREAT. The fuel pressure starts at about 8.5 PSI. The fuel pressure gauge is between the fuel pump and carb. After the choke completes its warmup cycle, the engine drops in rpms as expected. However, after a while, the fuel pressure starts to drop from 8 to 7 to 6 to 5. Once it gets to around 5, it sunddenly drops down to 2 and the engine dies. I replaced the fuel pump and it still does the same thing. I removed the gas filter and it does the same thing.

I don't know if the problem is heat or the carb. I don't see how the output pressure of the fuel pump can be affected by the carb. There is no fule by-pass in the carb and I don't believe the fuel pump has a pressure regulator that reacts to carb demand.

Can the fuel pump rod freeze? I removed the fuel pump and the fuel pump push rod seems to move freely.

Any suggestions? I am bewildered here.

Richie: Ok you are running a 600 cfm El. was it out of the box. If so it should be st up to go if not then you might have a accelerator problem but I do not think so.

My recommendation would be a Edelbrock Performer Series fuel pump #1721. You need to maintain 6 psi for street use and a little fun. I am not a Holley fan it sounds like something is getting weak. What it all boils down to is you have to correct the pressure. Where is your filter, newer vechiles with in tank filters have also ran into this sort of problem. popcorn The Truth is Out There (Good Luck)

The carb is right out of the box. Like I said, it runs great until the fuel pressure starts to decrease.

In an attempt to isolate the problem I removed the in-line fuel filter (between the tank and the fuel pump). I still experience the same symptoms.

I plan to disconnect the fuel line from the fuel tank and feed the fuel pump directly from a separate fuel container just to be sure that the problem is not in the gas tank.

I am also considering going to an electric fuel pump.

Richie: Your headed in the right direction with the fuel in an extra containor, and trying to isolate the problem. Never have added an electric fuel pump unless vehicle came with one, that's a different ballgame for me. popcorn The Truth is Out There (Let me know what happens)Edelbrook (manufatured by Essex) #1791 electric fuel pump for Carbs would be my choice.

Did you try it with the gas cap off? Maybe it's a venting problem.

I think Frets has the right idea. With a higher volume fuel pump, you need to run a vented cap.
Try taking the cap off.

JS