I'm not familiar with Toyota fuel systems. When I turn my key on my fuel pump starts running but, does not quit. Is this normal? With my other vehicles that have electric fuel pumps and FI the pump starts, pressures up and stops until the engine is started. I can hear gas returning to the tank. Could this be a failed fuel pressure regulator?
1994 4Runner
3.0l V6
5spd.

 

Sounds like the fuel system has been modified and wired directly to ACC... ECM ussualy gives a 3 second signal to the FP to allow it to pressurise.

Stock ECM?

 

All is stock as far as I know. Would a failed or failing pressure regulator cause this?
Will check to see if FP runs when key is on ACC.

 

As far as i know system pressure has nothing to do with it. No ECM has a fuel pressure sensor, it simply gives the pump a 3 second signal so that it builds pressure. If there is already pressure there then the excess fuel just gets returned to the tank.

 

your afm sends a signal to the cor relay to "run" the pump as your cranking and when the engine is running. Check to see if the door inside the meter is stuck open or not returning shut. That could cause it to send the "run" signal to the cor. Or maybe the Cor * circut opening relay* is shot.

 

Thank you for the response. Had one of those small tabs inside the AFM break off and ground the system out leaving me dead in the middle of 4 lanes of traffic. Read about this problem in another blog and found the broken tab when I opened the AFM. Runs great just don't think the FP is receiving the correct signal now. Does exactly what you described, fuel constantly returning to tank without engine running so have to assume the same is true while running. Looks like another $Zillion bucks I'll need to spend.

 

What year of truck and which motor? Make a request, surely someone on the forum will have a replacement AFM for you at a decent price!

 

look for a good used afm on craigslist. Or pm deathcougar he works at a toyota/ lexus wrecking yard in washington * Nix 99* and has good parts.

 

Thanks again for the replies. Found an AFM here locally. Will install soon. Should have kept my Bronco for a few more days.