aaron1969

hey its been awhile I've been experiencing a carb problem i recently replaced the fuel pump (mech) on my 350 sbc start car and gas is gushing out of the top of the carb.a holley 600cfm checked needle and seat all ok. hated this carb from day one. switched it out with a rebuilt quadrajet hook it up and i have the same problem plus gas coming out of the accelerator pump researched the fuel pump stock appearance non adjustable bought from napa #40987 looked it up online and it shows that it puts out 7-9psi is this my problem? or does anyone have any other ideas.I am looking for a lower rated pump have yet to find one that has both inlet and outlet that face directly forward and is not too deep as i have clearance issues with the frame any info would be great. thanks much Aaron oh so as to not start a war this engine is not in my 69 cutlass convertible (nor never will be)but I do need to get the car out of my shop every once in awhile to be able to make room for my cutlass

aaron1969

oh original carb was a holley 600cfm the one i hate

nsnarsk65cutlass

7-9 psi seems high to me my thought is around 6 psi.

oldcutlass

I agree, fuel pump pressure is probably too high since it did the same to 2 different carbs.

78Delta

I was thinking between 3 to 5 psi on the carbs, but sadly on the Holley site, there is no easy reference for fuel pressure requirements for their Carbs they sell. The regulators they sell run from 4.5 to 9 psi, and the one shut off switch is pre-set at 5 psi, so maybe in the 5 psi range?? I am running an Edelbrock (Carter AFB) carb on a SBC 350, mild cam, stock manifolds, hooked to a stock TBI electric in the tank pump and having no issues. The Holley 600 Vacuum or Mechanical secondary carb is a fine carb, but does has its quirks and needs to be setup properly. I do like the Q-Jet for daily driver and street needs less constant adjustments, plus you can modify the rods and primary jets as needed.



It sounds like you already have the investment in a good quality pump, but might be over capacity for your requirement. I would put in an adjustable pressure regulator. Once you know the pressure is correct, then start from there.

BILL DEMMER

6 pounds max, period.


bill

oldcutlass

If you have a vacuum gauge it also serves as a fuel pressure gauge to test. If you read the manual for your carb, it will tell you the required fuel pressure.