I've planed to leave town in 18 hours for a ride at Gray Rock. As of two days ago I lost fuel AND spark.

95 YJ, 2.5L, manual trans

I've checked all relays and fuses.

I did a resistance check on the ignition switch on the collumn. It's good.

I installed my computer in another jeep and it ran fine.

If I close the relay by hand, the fuel pump will run. It gives me the impression the PCM is not sending current to certain relays for whatever reason.


WTF is AUTO SHUTDOWN? Could it be the source of my problem? And how the fawk do I bypass is or check it?

Please help. I should be trailering up tomorrow.


Russ

check the cps and cam sensor

I wouldn't think the crank or cam sensor would kill the fuel pump. Would it?

Oh ya, and the check engine light won't come on.

No crank signal=no fuel pump, injector pulse, or spark.....

Crank position sensors go out all the time. That's where I 'm putting my money.:grinpimp:

I'll trade the cps for my buddys 94 yj when I go home for lunch. But I doubt thats it.

The fuel pump should kick on as soon as you turn the key to acc. position, regardless of the crank position.

I'll swap it in a few hours and post back. I hope it is the CPS at this point.

I agree, think it is the CPS from what you are describing. If it is the problem, buy two and put the extra in your tool bag for when it goes out on the trail.

I'll trade the cps for my buddys 94 yj when I go home for lunch. But I doubt thats it.

The fuel pump should kick on as soon as you turn the key to acc. position, regardless of the crank position.

I'll swap it in a few hours and post back. I hope it is the CPS at this point.

Yes, the fuel pump should come on for 1.7 seconds then shut off. Check for relay engagement when the key is turned to the "on" position. Once the pump "primes" for the 1.7 seconds, the PCM hibernates until it sees a signal from the cam sensor (first) and then the CPS (second). Both have to occur before the ASD relay activates and supplies power the fuel pump.

Good luck, with this and the slick MUD at GrayRock.

Scott

I had the exact same problem when I first got my 95 YJ this fall. NO check engine light, no fuel.

The auto shutdown is tripped since your fuel pump isnt kicking on to prime the fuel system.

It wasnt my CPS it was the ECM, I swapped one in out of my 91 and havent had an issue like that since. You said your ecm worked in someone else jeep but did theirs work in yours?

The auto shutdown is tripped since your fuel pump isnt kicking on to prime the fuel system.



Alright.

How do I bypass it or can I just remove it from the system? Or just reset it. I left the battery unhooked for about 5 minutes and nothing changed.

I've got a FSM and all it tells me is to troubleshoot the AUTO-SHUTOFF with a P?? scanner. There's gotta be a way to get around it.

I've got a 400m/c6/205 and propane carb taking up floor space in the garage. It's really starting to taunt me right now. But no time for that ATM.

{edit} I'll swap in the other ECM and try that also.

Thanks for all the help so far.

the auto shut down is triggered by the ECM and it wont let the ASD relay engage. Not sure if you can bypass it.

My problem was intermittent at first. Then if I left the key on for about 10 min the fuel pump relay would click rapidly and the check engine light would come on once the fuel system was primed. Then it would start up. It would run for as long as I wanted it to. Shut it down and boom no start. When it did restart and I could check codes, it wasnt throwing any.

I changed sensors, fuel pump, every relay, etc... nothing. Once I swapped the ECM boom it fired right up and no problems starting since. That was octoboer. Its a fairly common issue in 95 YJ's for the ECM to go bad, or so I have read.

I am not saying it couldnt be the CPS and its worth taking the 10 min to swap another in to check it. But my money is on the ECM. When My CPS went out in my old 91YJ, the fuel system would prime and the check engine light came on, I just had no spark.

If you can swap your buds ECM into yours, I bet it fires right up.

I went home at lunch. Put my buddys ECM and CPS both on my jeep. Nothing changed.

Installed my stuff on his, and his ran. I haven't swaped the cam senson, but I don't think that matters. I might try that after work for the hell of it.

I'm still convinced in my head it's the ASD. I'm trying to research that right now.

Thanks again for the help so far.

If the cps and ECM didnt help I would say its the Fuel pump. Did you try swapping around the relays maybe its a bad relay?

Take the horn relay out and use that socket to check the other relays.

If I close the relay by hand, the fuel pump will run. It gives me the impression the PCM is not sending current to certain relays for whatever reason.


:confused: how do you close a relay by hand?


http://www.dana60.com/sceep/yj_wireing.jpg


here ya go... start checking wires at the ASDR

I tried the shuffle method right out of the gate. No Go.

At lunch, I pulled ALL relays out of my buddys jeep and installed on mine. No change.


The fuel pump is good. If I pop the cap on the pump relay, I can close the relay by hand, and the pump runs.

My guess is, Either power is not getting to the ECM, or the ASD is telling the ECM not to distribute power out for the vital functions.

I may pop the cap on the ASD relay and manually close it and see what happens.

I read in another thread that if the O2 wires short, it can trigger the ASD. That's one more thing to check I guess.

:confused: how do you close a relay by hand?





here ya go... start checking wires at the ASDR


thanks Sceep.


pop the cap off a relay and look. It's uber simple. Be careful prying the cap, it's easy to break.

not sure about jeeps, but on other cars if the check engine light doesnt come on when you turn on the key the ecm aint gettin power for some reason.

Just jump between 22 and 24..

problem found!!! Bad connection at the firewall plug. I was loosing power as it went thru the plug to the interior fuse box. I'm booty fabing a temp fix with a toggle. I'll tear down the connector after the ride.

Thanks for the help everyone.

cool.. have a good trip and dont be "that guy"