4.0 only runs for a couple seconds

[PNW Rob]

Took about an 80 mile trip and died while on the freeway. It had been running fine up until then. I found that I cannot hear the fuel pump when ignition is turned on and no fuel coming from the schrader valve. I removed the fuel pump relay, jumped the pins and heard the pump humming and got fuel to come out of the schrader. Replaced the relay and same issue, no fuel pump sound and nothing coming from the schrader.

I've already replaced the fuel pressure sensor, the TPS and the air idle control valve. The fuel pump (Omix brand) and fuel filter were replaced a couple years ago, probably only 5 or 6k miles on both. Any ideas?

 

[Chris]

What is the fuel pressure at the rail when it's running?

 

[Flyer58]

If you can jump the fuel pump relay and get the pump to run, then that may indicate the signal wire for that relay may not be working to energize the relay.

Will the engine run if you jump the relay and try starting it?

I believe the relay signal comes from the ECU. The ECU initially sends a 1-3 second signal to prime the injectors before starting. If all other parameters are met, the pump will start running again to keep the engine running. It has a safety function to shut off the pump if you're in an accident.

That programming is all built into the ECU. It doesn't necessarily mean the ECU is bad, You may have a bad wire or connection.

I don't know the wire color or pin number into the ECU but it can be found in a Factory Service Manual. See the Reference section.