fuel pressure problem, help me out

[slowhatch82]

fuel pressure is 30psi when car is running, fuel pump primes, but when i shut it off it drops to 0 right away, isnt it supposed to hold pressure? is this the fuel pump/regulator or what?

also could this be the cause of my car struggling to go above 3500/4000?

thanks
chris

 

[FceDncr]

How are you able to read your fuel pressure? And yes, it should hold for at least awhile. You either have a bad FPR or fuel pump.

 

[PRO50SC]

How are you able to read your fuel pressure? And yes, it should hold for at least awhile. You either have a bad FPR or fuel pump.

What he said.

 

[axeman]

it should hold pressure for a while and still have some pressure even hours later. something is definatly wrong. sorry, i'm not sure what it is though. i would think it would be either the fpr or pump. someone will know, just hold tight.

 

[slowhatch82]

alright thanks, i know a few guys at the shop, they have a pressure gauge for testing fuel pressure...tires pressure, whatever...

so do you guys think my car cutting out upper rpms is related to this problem?

 

[stangbear427]

Yes, but your problem isn't that it doesn't hold when you shut it off- it's that you're starving for fuel. Stock fuel pressure is 38psi @ 0 vac. If you don't have an adjustable FPR, you need to get one and crank it up where it belongs before you screw your engine up. It could also be a bad pump that isn't supplying the fuel you need, but the moral is, you don't have enough pressure. At 3500+ rpm, you should have 40psi or more, depending on how much throttle you're giving it.

 

[stangbear427]

Woah! Just went to your webpage- which car are you talking about, the '88 or the '82? On a carburated engine, 30 psi is about twice what you should have- which would also give you serious drivability troubles.

 

[slowhatch82]

the 88...i sold the 82 alittle while ago....man i miss that thing! it flew compared to the 88, but i guess once i get it running right with a few mods it'll be ok right

alright im gona get a adjustable fpr and try that out, if it doesnt work i guess ill be dropping the tank! fun stuff!

thanks guys

 

[jerry beach]

Fuel pressure should hold steady for 1 min. after the pump is turned off. Its highly likely you have a bad fuel pump check valve. I think its safe to say you need a new FP. Its no big deal, but the edges are very sharp so be careful. I just put in a BBK 155lph pump, and it would not sit in the hanger and bolt in place. The nipple on it was longer than stock. The easiest way to make it fit was cutting some of the hard line off on the factory hanger.

Do not run the car up to the point where it cuts out, cause lean is bad.

 

[slowhatch82]

alrighty, ill stay away from it...thanks guys