96 explorer 4.0 fuel pressure p.s.i.??

[porshapower]

Ran a test on fuel pressure today. I am getting 28 psi with engine running. I disconnect vacuum line at regulator and am getting 38 psi. Turned off motor and got 38 psi for 20 minutes. How are these numbers?? Chasing a slight stumble at idle. Runs/drives like new. Pull the vacuum line off regulator and stumble is still there. Its a 4.0 1996 explorer 5speed. Thanks!! Nelson

 

[MalcolmV8]

I don't know a lot about fuel pressures but I do have a gauge installed on the fuel rail of my 92. It's been a while since I've looked at it but 28 seems low. I was thinking it sits around 40 PSI with vacuum pulled and around 35 ~ 38 PSI with vacuum at idle.

 

[porshapower]

Is it the same for a 96??

If it is what can be causing it to be low?? ThanksNelson

 

[Glacier991]

a faulty fuel pressure regulator, or a weak pump, either one would do this. And I am with Malcolm on the pressures.

 

[Xzibit A]

that sounds around normal, mybe a little low bout not enough to cause a rough idle, check your upper intake gaskets with some carb cleaner, they often leak

 

[spindlecone]

I don't know a lot about fuel pressures but I do have a gauge installed on the fuel rail of my 92. It's been a while since I've looked at it but 28 seems low. I was thinking it sits around 40 PSI with vacuum pulled and around 35 ~ 38 PSI with vacuum at idle.

Is there a gauge that can be screwed on the schrader valve, left in place

 

[MalcolmV8]

Sure. I don't have my receipt right in front of me but I'm pretty sure this is the one that I used. Look at summit part # ACC-74725

 

[porshapower]

Upper intake gaskets done!!

Truck running much better. I will test fuel pressure tomorrow to see if its better. Would a leaking upper manifold cause low fuel pressure?? I cleaned up the intake really good and inspected for cracks..looked good. I got a FELPRO gasket kit from Advanced Auto and the box said 96-97 4.0 v6 Quantity:6 but my 4.0 v6 1996 only uses 3 gaskets?? Why the xtra 3?? Thanks again!! Nel

 

[Xzibit A]

might have been lowerintake gaskets in the set too, the only way that the intake would affect fuel pressure is if it was a major leak and you had low vacume, which you would have high fuelpressure

 

[spindlecone]

Sure. I don't have my receipt right in front of me but I'm pretty sure this is the one that I used. Look at summit part # ACC-74725

Thx M
Just ordered that puppy