On a 1995 Jimmy 4 door 4.3 CMFI, is the fuel pump regulator in the tank with the pump or is it a separate unit?

 

Just so we're all on the same page here, are you talking about the fuel pressure regulator???

 

Yes, Fuel Pressure regulator.

 

The fuel pressure regulator is located inside the intake plenum and is attached to the CPI spider.

 

thank you, I saw this on previous posts. Me pressure at the fuel rail is 40 psi. this is before the regulator. so I am thinking that it is not the FPR. Do you think 40 PSI from the fuel pump would prevent starting?

 

It still is possible that it is the fuel pressure regulator. Just because you are measuring between the pump and the regulator doesn't mean that the regulator isn't at fault. The function of the regulator is to maintain fuel pressure in the line. It maintains the fuel pressure by allowing fuel to bypass back to the tank. If it is allowing too much to bypass, then it will result in low fuel pressure at the fuel pressure test port.

One thing that will help diagnose the problem is to watch the pressure after you turn the key off. If it bleeds down, then I would suspect the fuel pressure regulator is either leaking back through the return line to the tank or into the intake plenum. If you really wanted to cut the rest of the fuel system out of the diagnosis, you have to test at the fuel filter, adapting from the threaded for the filter to the gauge you are using. This will isolate the pump and should result in fuel pressures above 60PSI. If it doesn't, then you have a weak pump.

At that point, you should look at whether the electrical connections are proper. This comes in most often when a pump has been replaced which required a different electrical connector be spliced in. Poor splice connections will result in poor pump performance regardless of the brand of pump used.