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Old 05-19-2009, 07:54 PM   #1
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Help with NO Spark and NO Fuel

Got a real head scratcher going here. . . .

1994 2.5 YJ. So far I have replace the CPS (Wires were frayed) and reseated the connection on the cam sensor. I have NO fuel and NO spark. Relays seem OK- i subbed out known good relays through the horn circuit and verified they work- so the shutdown and fuel pump relays are good.

CEL comes on when key turned to "ON" but I cannot get it to flash codes for the life of me. CEL just stays constant.

I cannot hear the fuel pump priming when I turn the key on, but am wondering if the cam position sensor could be bad and be keeping pump from priming.

Any other thoughts out there?

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Old 05-19-2009, 08:05 PM   #2
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if fuses are ok also, i'd start looking at ecu, and distributor (easier to service as a unit). with the wires frayed on the cps, which happens, you'd think you'd have fixed it. obviosly you repaired the bad wires right?

distributor would be easier to sub known good parts for, or return if it didn't work. i'd try it first, for those reasons.

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Old 05-19-2009, 08:11 PM   #3
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obviosly you repaired the bad wires right?
No- I replaced the whole unit. The frayed wires were too close to the actual sensor to repair.

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distributor would be easier to sub known good parts for, or return if it didn't work. i'd try it first, for those reasons.
Do you know if the Cam Position Sensor which is part of the distributor would keep the fuel pump from priming?
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Old 05-19-2009, 08:13 PM   #4
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it usually wouldn't keep it from priming for the first few secs...but it can cause no pressure after that.

you can't get any flash codes by cyling the key from off to on 3 times? if the computer stored a code for the cam sensor, and recognizes no signal, it may stop the fuel. i'm not sure if a yj computer was that sophisticated, now days they'll do that.
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Old 05-20-2009, 06:24 AM   #5
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you can't get any flash codes by cyling the key from off to on 3 times? if the computer stored a code for the cam sensor, and recognizes no signal, it may stop the fuel.
That's correct. When I cycle the key and go back to "ON", the CEL light is on, the upshift light is on, and the seatbelt light is on with the buzzer. Then the seatbelt light goes out and the buzzer stops. CEL and Upshift light stay on and no flash /codes.
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Old 05-20-2009, 07:07 AM   #6
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Here is my 2 cents-

I just replaced my ECU last night. I had NO spark, NO fuel pump prime, AND NO CEL. If your ECU was gone/not getting power, your CEL wouldn't be coming on.

I know in one of the manuels I was looking at, it stated that some of the trouble codes would not make the CEL flash...

IF i find it again, I'll post it.
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Old 05-20-2009, 04:35 PM   #7
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Excellent Thanks!! If the trouble codes won't make the CEL flash, then how does one get them out of the ECM? Can the old OBD-1 ECMs be read by a code reader like the new OBD-2 ECMs?

If you could confirm that not all codes make CEL flashes, that would be fantastic!!

Want to get this thing running so I know what I've got. Then I am contemplating a complete frame off. Got a good frame and great sheet metal.
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Old 05-20-2009, 06:44 PM   #8
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Here is a link for the trouble codes, and the procedure. Let me look around some more....

1991-1995 Jeep Wrangler YJ - Trouble Codes
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Old 05-20-2009, 06:45 PM   #9
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Old 05-26-2009, 08:26 PM   #10
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to get codes you have to cycle the key 4 times. the codes will start after that. the fuel pump could be on the out. sounds strange consiering feul pumps are either good or bad,but my 93 zjdid that.
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Old 02-01-2010, 11:11 PM   #11
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having the same problem with my 91 2.5L i only had it for 3 days and it broke... no spark or fuel. fuel pump works i tested it, havnt tried to read codes, but i pulled the ecu out and dirt and dust came out, so im assuming when i was offroading i got it wet or muddy? or could it be the ignition modual? im in the middle of doing the truck bed paint liner right now tho tothe interior n its looking great!
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Old 02-02-2010, 08:46 PM   #12
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It all sounds like the ECU to me. Happened to me too. Got a new one off of ebay..couldn't find one anywhere else. Has served me reliably since then. Try to check for something that could have made the ECU go, like arcing at one of the components of the ignition system, including starter. Just to make sure it's not that and you don't buy a new computer and blow that one too.
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Old 02-05-2010, 07:24 PM   #13
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I am having the same issue with my 91 4.0. I read somewhere that the ECM can be used from a same year XJ SOO after a trip to the JY i tried it and no luck. does it have to be mounted to firewall to work? ( I just plugged it in). i checked the codes and got (Alternator field) the Alternator is fairly new, maybe 2k miles ago. so what else falls under the alternator field?
Going nuts ova here. Having withdrawals its my daily driver and need to work...
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Old 02-06-2010, 07:04 PM   #14
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can i use any ecu from a yj 2.5L 5spd or do i have to match the part numbers?
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Old 02-06-2010, 08:24 PM   #15
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I'd use it from years that were similar. IE: 91-93 are very similar, 94-95 are very similar, etc. I have a 94, but my ECU is from a 95.
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Old 02-07-2010, 12:19 PM   #16
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so im safe with any 91-93 then... ebay here i come... i live in south jersey we just got 2feet of snow n i wanna go play so bad but its stuck in the garage not runing
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Old 02-07-2010, 12:22 PM   #17
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1 more question, is it safe to extend the harness for the computer (cut and crimp) so i can relocate it inside up under the dash?
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Old 02-07-2010, 02:54 PM   #18
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1 more question, is it safe to extend the harness for the computer (cut and crimp) so i can relocate it inside up under the dash?
That's a tough one. You will have to deal with resistance and all that crap, these things are pretty sensitive....not a bad idea though, it is a lousy place to mount it.
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Old 02-08-2010, 04:08 AM   #19
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looks like im just gonna double bag it with like plastic bags n ziptie around the wires so it dont get wet anymore
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Old 03-06-2010, 05:16 PM   #20
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new computer fixed it!!! but now got bigger problems
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Old 03-08-2010, 05:40 PM   #21
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can anyone help wit my newer no start problem? http://www.wranglerforum.com/f8/no-s...tml#post563728

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