powderpainter

please do my next step is a computer/ecu

but dont think thats the problem

solderjunkie

You wrote that you supplied 12v to the pump... did you do that at the fuel pump relay?

If you jump 30 to 87 on the relay and it runs, you get to rule-out all of the fuses and the wiring all the way from the battery to the pump.

powderpainter

I did jump the pump with a 12v supply but not by jumping the relay ,,

powderpainter

well I put a new ecm and still no change,
so has anyone else replaced all of this and still get nothing-

please post it and how you fixed it

new ecm ,new pump ,new cps sensor ,

ET JEEP

Seems you may have a wiring problem. When you turn the key to on the ECU turns on the ASD and Fuel pump relays for about 2 seconds until you crank the engine. During this time the fuel pump should run to prime the engine.

It does this by grounding pin 86 or 85 of the relay. I say either because it seems that they are wired either way.

To test this theory do a voltage test. Remove the fuel pump relay. Find the socket to pin 30. This socket should have battery voltage at all times. The socket for pin 87 is the fuel pump feed. If you jump these 2 sockets, the fuel pump should run.

Now, with the key on, you shoulld have battery voltage to the socket for pin 86 or 85. One of them will have battery voltage. The dead socket will be the ground for the control circuit. When you turn your key to on, the PCM grounds the ground socket which activates the relay and turns the pump on. The grounding will only occur for a couple of seconds until you crank the engine. Doing a continuity test for this socket may reveal something.

The ASD relay is wired the same way. Since you can run the engine by jumping the fuel pump, it seems that the ground for the FP relay may be the problem.

BTW, the heated O2 sensor is also on the fuel pump feed. If the fuel pump does not run jumping the relay, the O2 sensor may be the problem. I see this circuit for the 5.2 engine. The 4.0 should be the same.

fsalcedo

Did you ever fix it I'm having the same issue now

powderpainter

I never fixed it and scrapped the vehicle .
it’s gotta be a fusable link I just didn’t have the time or patience to deal with it after dealing with it for so long.