100 psi fuel pressure


New Member
Jun 29, 2004
Was coming home and my fuel pressure was reading 100 psi.
Running 93 octane with 42 lb injectors FP should be around 39 with car idling no E85 or anything like that.

This was at a stoplight. Some part throttle to get moving and it went to 110. My setup is about 10-15 years old with a mechanical FP gauge in the car separated with an isolator unit that has coolant in it so it is a safe setup. When I got back home and shut the car off the next day it primed back to normal. Does this sound like bad isolator, gauge or could the FP regulator be going bad. The car ran ok during the ride home but I was afraid to get it under boost like that.

I would lean towards gauge/isolator...not sure what type of fuel pump you have but if it's stock type i doubt it could even hit 100 psi.