Fuel Pressure Question...

classic · #1 06-28-2011, 11:17 AM

Question for you knowledgeable carb guys out there... My 383 stroker in the
'65 has a Holley electric fuel pump with a 750 Street Avenger carb.

When I first start it up the fuel pressure per the gauge is running at 7 psi +/- but after it warms up it will drop down to around 2 psi. Is that normal or should it hold at a constant 7 psi the entire time the pump is running?

Thanks,

Greg

smokenjoep01 · #2 06-28-2011, 12:11 PM

I dont use a psi. regulator on my car, but I do use them on the wet nitrous systems I build for bikes. Were are you measuring pressure? In normal operation it should stay at the set pressure.

classic · #3 06-28-2011, 01:08 PM

I have the gauge located right at the inlet of the fuel lines going to the carb.

Greg

68ChevelleSS · #4 06-28-2011, 01:29 PM

I don't run an electric pump on either of my cars but mine runs constant whether its just started up or warmed up. My pressure is at the same location as yours. How does it run when its reading only 2 PSI?

classic · #5 06-28-2011, 03:37 PM

Quote:

Originally Posted by 68ChevelleSS

I don't run an electric pump on either of my cars but mine runs constant whether its just started up or warmed up. My pressure is at the same location as yours. How does it run when its reading only 2 PSI?

That's what I have been troubleshooting... It's strange but it will run fine at the rate even under load but every once in a while it just shuts down like turning the key off. Gives me no evidence that it's going to happen. I don't know if it's just running out of gas in the bowls as it starts right up again. On Saturday I did a total of 8 passes up my driveway with the car dying on me only the first run. The other 7 times she laid 75 foot rubber each run and never died. Checked out the PSI and it was at 2.5???

Weird - Greg

68ChevelleSS · #6 06-28-2011, 05:46 PM

Wow thats is really weird. Sounds like my squeaking problem. lol. Hmmm. Have you taken it out and ran it at WOT or revved it for a extended period of time? When you're letting rubber fly for 75 feet it might be keeping enough fuel in the fuel bowl to allow you to do that. I doubt that your 383 will run for an extended amount of time at WOT with only 2.5 psi. I know mine requires at least 6-9 psi or 110/130GPH. I recently blew a diaphram in my holley fuel pump and while waiting for my rebuild kit I installed a stock pump and it ran horribly at WOT but normal at idle. Voltage problem at the pump? Just something to think about.

classic · #7 06-29-2011, 02:38 PM

Yeah, it's weird all right! I have a Holley mechanical pump coming from Summit rated 6.5 to 8 ps1 and 110 gph. I will also check the voltage at the pump as I did have a problem in the wiring to where I had to wire the pump direct to a manual switch.

Thanks - Greg

68ChevelleSS · #8 06-29-2011, 03:57 PM

Let me know what happens..... Boyd