90 4.0.... if my guage is right im only running at 7 psi. new pump didnt replace filter....doing that now.

 

How is it running? Symptoms?

For 87-90, your pressure should be 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator and it should jump to approximately 39 psi.

If you have only 7 psi, you have a SERIOUS flow problem! Hopefully that filter may take care of it. If not, the regulator is still in play, although more unusual for low pressure.

Also be sure that the vacuum line leading to the regulator is dry. If it is wet with fuel, you have a ruptured fuel pressure regulator.

 

filter didnt help. ordered another new pump. it was running fine then started sputtering and died. it will restart running rough and die. a few times it did stay running for a short amount of time. of course the tank is full so i have to pump some out of it. my guage is homemade so i hope its accurate.

 

Sure would like to see pics of that.

 

here is my homemade fuel pressure guage. guage from hvac guages, hose from hvac guages, flare to pipe thread fitting. i used it on a 2000 ram cummins with a fuel issue and it worked.

 

Seems to be an accurate gauge, but I'm not a gauge expert.

At 7psi, though, I don't know it it'd even run....but if the gauge is accurate and its trying it obviously can.

I'd start with the pump, that'll probably solve the issue.

 

ok...dont know why i didnt think of it before...i checked the guage on the running xj i have...it read 35. it was holding 10psi after sitting overnight . the nonrunning xj bleeds off immediatel. so regulator?? if its stuck open it wouldnt build pressure, right?? im replacing the pump again anyway. they gave me a set up for a 13 gallon tank instead of a 20.

 

got my fuel pump on and its running normal again. before taking the last one back i inspected it and found the hose clamp on the outlet of the pump was placed above the barb so it wouldnt hold or build pressure. hope this can help someone else

 

Better go find "that guy" and

LOL glad you got 'er fixed and thanks for the update!

 

x2!!

Sucks that you had to deal with the garbage, but thank you for the info!

 

Hi there is fuel pressure on the 2000 50 +/- 5 or .5?

 

49 +/- 5