1G Oil pressure sensor disconnected = no start?

[91Bomb]

Is it connected to oil cooler and if it came off would no power be sent to fuel pump on start-up? Because I just changed a bad alternator and car then ran fine so I turned it off and put splash shields back on near oil cooler and now today no start! FP runs with 12v applied directly at pump connector but ignition is not sending any power to it. So thinking might of knocked off a wire at oil cooler or in that vicinity. ECU, mpi relay are all good and even swapped in another CAS but no power to FP yet. Trouble codes + all fuses chk good too.

 

[Dsmkauai]

No connected to oil filter housing and shouldn't prevent starting. There's only a pressure switch for dummy light and the gauge sending unit. Somthing else either fell off or your battery is toast. Have you tried jumping it. Have you checked the battery voltage? How long where you running with a dying alt? It could have taken out the cranking ability of the battery.

 

[pauleyman]

Did you check the fusible links at the battery?

 

[91Bomb]

Battery voltage is good and cranks strong. Fuel pump does not prime when turning ignition on. Checked all fuses/relays underhood, inside car, + on battery. FP tests good at pump connector on gas tank.

 

[steve]

Fuel pump does not prime when turning ignition on.

1G's don't prime the pump when you turn the ignition on as a rule, it does happen sometimes if the CAS glitches on power up and makes the ECU think the engine is turning. The pump is started when you turn the ignition switch to START via one input to the fuel pump side of the MPI relay. The power for the running the pump comes from the ignition circuit where the power for the ECU and sensors comes from the MPI circuit.

Does the ECU turn on the CEL for five seconds and turn off? Does the boost gauge move to 0 until you start cranking?

 

[91Bomb]

Thanks for the great info!

Finally got the car started last night and runs good now. I believe the problem was just corroded wires on fuel pump rewire I did 5 yrs ago. The ground wire to chasis looked quite bad and power wire from ignition didn't look too good either. Alt was shorting out lately making a whining noise and drawing 2 amps from battery with car turned off. So, don't know if one problem caused the other or just a coincidence but glad to fix this one! Think I'm going to run the ground wire into cabin when I get some decent wire.