Fuel pressure at idle?

[Kraig]

What should the fuel pressure at an idle be? My 1991 Festiva has 28 psi.....I think it is supposed to be 36?
t also does not hold residual pressure, runs like crap at speed, I believe the regulator is going bad.

Thanks for the help!

[WmWatt]

Haynes manual suggests
38-44 at fuel pump test connector engine not running
30-39 at attached vacuum sensing hose at idle
36-44 at detached vacuum sensing hose at idle
for all fuel injected engines

Sorry I can't help more a I have the carburetted engine and it's the only one i"ve worked on.
Hope it helps.

[Studebaker]

THe few times I have checked it it was in the 30's

[Icedawg]

Check your fuel filter. If you can't blow through it with almost no effort, then it is plugged and restricting pressure

[Kraig]

The filter is brand new, tank is new, pump fairly new.

[WmWatt]

If there were leaks you'd smell fuel so look for constrictions and blockages?

[Icedawg]

The filter is brand new, tank is new, pump fairly new.

mmmmm
Well with all that new stuff it should be working, shouldn't it. Sounds like you need a deeper check, after looking for leaks.

With all those parts changed, and it not working well, you should probably make a very careful check that all the lines are properly connected to the right places.
You might want to take the pump back out, and make sure all the fittings and hoses are securely connected to it, internal to the tank.

Then check pump performance.
You will need to check the fuel pressure with the flow into the fuel rail blocked to see if it goes up to about 60 or 70 psi.
You will need to check the test you have done, measuring pressure with the fuel flowing at idle, which should be in the mid to high 30's.
And then have some one increase throttle rapidly and see how the fuel pressure responds. It should stay in the mid to high 30's or above.

If all the lines are good, and the pump can make 60 to 70 psi when there is no flow, then you have to think about the fuel pressure regulator on the return to the fuel tank as being the possible source of the problem. Not sure how to test that, except for swapping another one in its place.

[Kraig]

I am suspecting the regulator is not good. Will check pump pressure by itself this weekend....

[Kraig]

It ended up being the fuel pump. It now has 28psi at idle and it actually changed pressure as maifold vaccum goes down when you give it throttle... up to around 40ish.
Runs much better than it did. Get a check engine light when doing around 65mph and then goes away when you slow back down. Need to pull codes,, have a new O2
sensor on hand (suspect it may be the problem) but it is really rusty and being a pain to get out !

[Kraig]

Just got the O2 sensor out by cutting most of it off with a hacksaw and using a real 6 point socket and breaker bar.
Just got back from a test drive. No check engine light! Had her up to 80 too.