fuel pressure rising??

strokin'_tatsch · May 25, 2012

Hey guys. Got a problem with my OBS. Fuel pressure seems to be continually rising.. I looked down at the gauge and it was reading 90psi. Drove it another 2 miles so I could park it and check it out. By that time it was at 95psi. I shut it down and pressure bled off, but as soon as I started it, back up to 95psi. I dropped the pressure on the FPR and the gauge dropped with it, so I set it back at 70psi and drove it around the parking lot for a few minutes and in that time it came back up to 75psi and I shut it down so I could walk in the movie theatre with the woman.

The specs on the fuel system is stock pickup and return and fuel selector valve is still in use. After that is a Dieselsite system. Stock SD pump, Dahl 2 micron and Aeromotive 100 micron inline filter, full regulated return with Aeromotive regulator and electric fuel pressure gauge with the sending unit in the FPR. I haven't put a mechanical gauge on it yet, but I can tomorrow. The engine is running good and it doesnt seem like anything changed. I'm confused on this one. Any ideas guys???

Mike M · May 25, 2012

strokin'_tatsch said:
Hey guys. Got a problem with my OBS. Fuel pressure seems to be continually rising.. I looked down at the gauge and it was reading 90psi. Drove it another 2 miles so I could park it and check it out. By that time it was at 95psi. I shut it down and pressure bled off, but as soon as I started it, back up to 95psi. I dropped the pressure on the FPR and the gauge dropped with it, so I set it back at 70psi and drove it around the parking lot for a few minutes and in that time it came back up to 75psi and I shut it down so I could walk in the movie theatre with the woman.

The specs on the fuel system is stock pickup and return and fuel selector valve is still in use. After that is a Dieselsite system. Stock SD pump, Dahl 2 micron and Aeromotive 100 micron inline filter, full regulated return with Aeromotive regulator and electric fuel pressure gauge with the sending unit in the FPR. I haven't put a mechanical gauge on it yet, but I can tomorrow. The engine is running good and it doesnt seem like anything changed. I'm confused on this one. Any ideas guys???

My bet is a bad gauge. Anything but a water-filled gauge has a hard time surviving the vibration of a diesel. I bet pressure is steady with a mechanical gauge hooked up.

strokin'_tatsch · May 26, 2012

Im hoping its the gauge sending unit, but I've never seen one act like this.

Update: just got out of the movies. Literally right before I walked into the movie, I set the regulator to 70 psi according to the electric gauge. Came out and started it and it was reading 60psi. Makes sense because I backed it off from where it was originally set. Drove it around for 30 miles just to see what it would do and after 30 miles it had risen to 78ish psi. It still drops pressure when I stand on it like it has been, just not as much. It used to drop from 70psi to 25psi on a hard pull. Now, I just ran it when it was up to 70 psi and it only dropped down to 45psi... I haven't seen a gauge sender act like this before, but I hope that's what it turns out to be.