HELP ON 91 PATHFINDER

[reaper]

I ha 91 pathfinder that quit running i replaced the fuel pump,fuel regulator,fuel filter,and the fuel sensor it has about 40 pounds of fuel pressure, changed the computer and it has spark and it will run on starting fluid does any one have any ideas on how i fix this. otherwise it will be going to a wrecking yard.

[Precise1]

Have you checked the ECU to see if there are any fault codes?

Sounds to me like your injectors aren't firing. Can you hear them clicking?

 

B

[RF600]

If the injectors are firing and you have spark, the only other thing would be air. Have you checked the maf?

Edited February 8, 2015 by RF600

[reaper]

the ECU was wiped i dont hear any clicking

[reaper]

and it does run on starting fluid

[Slartibartfast]

Okay, so, the fuel is making it to the engine bay, but not into the engine. This suggests your injectors aren't injecting.

 

The way I've heard to test injectors by their clicks is with your ear up to a long screwdriver on the injector with the engine running. That sounds like a PITA with a motor that only runs on ether. I would also be surprised if you had six bad injectors, so I'm guessing the problem is with the wiring.

 

You can check the wiring by unplugging the connector on an injector you can get to and testing it with a meter while someone cranks it. I suspect you'll find no signal. All six injectors have two wires, one which is their individual wire from the ECU and common that they all tie into (which also seems to go to the ECU). The six individual wires go to an eight-wire plug (shared with the ignition system, so I doubt the problem is with this one). Looks like the common wires are white and red coming out of the injector plugs, but black and white after they join in the harness. This ground goes through a six-wire plug and into the main harness, near as I can tell from the diagrams in the service manual (EF&EC 8 and 9). I would try to find that six-wire plug with the injector ground, see if the plug is clipped together properly and clean inside, and test what should be a black and white wire with a meter against battery + and -. I suspect it's a ground, so you should see voltage to + with the engine on/cranking, but I could be wrong on that.

Hopefully the issue's in or near that plug (or at least in the injector harness) and not in the main harness between there and the ECU.

You can download the shop manual here: FSM. Download it, it comes in handy. There's probably a troubleshooting bit for your issue or at least a better explanation of the injector circuitry, I just went straight for the diagrams.

[Precise1]

 

The way I've heard to test injectors by their clicks is with your ear up to a long screwdriver on the injector with the engine running. That sounds like a PITA with a motor that only runs on ether. I would also be surprised if you had six bad injectors, so I'm guessing the problem is with the wiring.

 

You can check the wiring by unplugging the connector on an injector you can get to and testing it with a meter while someone cranks it. I suspect you'll find no signal.

I highly recommend a mechanics stethescope for anyone who works on vehicles regularly, they are under $10 and worth it. Yes, a metal rod or long screw driver cupped to your ear will do almost the same thing.

The injectors should be clicking when you crank the motor; the ignition is on, and the dizzy is turning and the motor needs gas to fire.

 

I agree, it sounds like a problem in the upstream wiring, and at that point, I'm not much help. The FSM should walk you right through the trouble shooting, it is quite indepth and the 1994 (earliest version) should be virtually identical to your 1991.

 

Thanks for posting the link Slart!

 

B

[reaper]

Thanks to everybody that are trying to help