Thread: Fuel pressure problem...

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Hi all,,

I noticed after running my motor for about 1/2 hour the fuel pressure gauge drops to almost 2 psi, from 6psi. i have a mechanical pump 80gph, fuel pressure regulator set at 6psi, 2 edelbrock 4bbl carbs 500cfm's. pump does not seem to get hot. Any suggestions?

you have so many vairables, fuel line size, float settings etc. does it drop off at a idle, or high rpm. do you have a regulator,where is it located? maybe its just me but we always run a elec. pump with multi carb setups.

Originally Posted by Dean C.

Hi all,,

I noticed after running my motor for about 1/2 hour the fuel pressure gauge drops to almost 2 psi, from 6psi.

If you have one of the small 0-15# Marshall/Moon/Jegs/Summit generic "sealed liquid" fuel gauges mounted in the hot engine compartment this is a very common problem. What happens is the sealed gauge becomes pressurized and the reading changes. Two things to do, 1) check the fuel pressure with a real shop quality pressure gauge so you have a known pressure, 2) turn the small gauge so that the rubber fill plug on the back is turned "up", then "when the gauge is hot" open the rubber plug (the glycern will not run out) and allow the internal pressure to be "bled off" and it will work just fine.

yea i have a jegs liquid filled guage. the fule pressure guage is mounted on the dual feed line it sits flat ( you look straight down at it) the regulator is mounted right at the dual feed line and then the ruber line goes down to the pump. pump rated at 5.7-8psi 80gph. all fule line is 3/8. This problem happens at idel it does not matter if i rev the engine the pressure does not rise more than 1/2 pound acording to the guage.

Thanks guy's i drained the liquid out of the guage, it actually made it more acurate ( in comparision to a shop guage) and it's working fine now. pressure at 5.5psi running for over an hour...