fuel pressure below spec

[dracon79]

Connected a fuel pressure tester up to my rail.

 

With the key on no engine start the pressure was about 33 psi when I started the engine the psi went down to 27 psi and with the vacuum hose off the regulator the pressure went up to 34 psi.

 

The pump and regulator are brand new.

 

The orings on the injectors look bad though and it looks like theres three different color rings around the injectors so I wonder if thats the problem???

 

88 Jeep comanche 2wd 5 speed 4.0 engine

 

The manual says 31 psi with engine running and with vac hose off 39 psi so definitely below specs. And the performance shows it.

[mjeff87]

change the fuel filter? Might be clogged a bit.

 

Jeff

[HOrnbrod]

change the fuel filter? Might be clogged a bit. Jeff

 

If not the filter, check your new regulator. You're getting the correct 7-8 psi delta so the vacuum is pulling your regulator, it's just set low. I guess your new regulator is not adjustable? And check your fuel pressure gauge against a known good gauge too.

[dracon79]

fuel filter is also brand new. Yeah the regulator is not adjustable. This is the third pump I'm on from shucks a carter/bosch.

 

The first pump last a month the second one never worked and this is now the third one from them.

[Oizarod115]

fuel filter is also brand new. Yeah the regulator is not adjustable. This is the third pump I'm on from shucks a carter/bosch.

 

The first pump last a month the second one never worked and this is now the third one from them.

 

buy somewhere else ;) oem parts are ALWAYS the best, albeit the price shows but it beats replacing it 3x :headpop: