I have a 90 Eclipse 2.0, which runs strong for about 30 minutes until fully warmed up and then the fuel pump just starts to surge, seems like the fuel relay is turning on and off, on and off and not regulating the fuel pressure. Anyoneknow what would cause this? MFI? Fuel Pressure regulator? EGR?

Thanks in advance with any help or input you may have.

 

Are you sure it's the fuel pump? The fuel pump is either on or off. The fuel pump regulator...umm, regulates fuel pressure and the injectors do the pulsing.
You may want to take a voltage reading at the battery and then one of the interior accessories like the cig lighter socket. You may also want to check for intake leaks.
Do you have a turbo Eclipse or did you mean a 1.8L N/T 4g63?

 

The motor is a 2.0L N/T
I think the Fuel Pump is fine, the problem is the somewhere in the system a sensor is causing it to surge on and off, you can feel the fuel line and feel the high pressure surge, and while driving under throttle the engine surges. It should be providing a constant pressure or smoother regulation.
Voltages are fine.
While checking hoses and vacuum lines last night I found a split in the PCV hose, minor but none the less it was a splitand replaced it so we will see how it runs today
Any other ideas

 

Well the surge is still there so it wasn't the split PCV hose.

I can usually get the surge to stop (temporarly) by turning the ignition off and restarting it and it will run fine for a short time and then start surging again.

Anyone have any other ideas?

 

I think its your fuel pump personally