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DaggersEdge 10-19-2012 12:41 PM

YJ Starting Issues
I’m trying to get my 1992 YJ road ready for my daughter. It has been a couple of years since it was on the road. I have gotten her running after changing the fuel injectors, the fuel pump, this kept her running for about a week then I lost fuel pressure in the fuel rail and had no spark. I then replaced the crank position sensor, the throttle position sensor, the coil, the distributor cap, the spark plugs and wires. Still no luck, until I left the key in the on position for about twenty minutes when I hear the shut down and the fuel relay start clicking. I turned off the key and then tried to start it and she did finally fire but would not stay running.

The boss on the distributor was cut off about 10 years ago by a former friend I had work on it the last time I had an issue with her running (big mistake ever letting him touch my ride). I adjusted the distributor a few times and finally got her to run. After she warmed up she started to spit and sputter, so I repositioned the distributor again until she smoothed out. I was then able to drive her for hours with not issue. I could shut her off and she’d start right back up.

However the next day again I had nothing, I also noticed that neither my “Check Engine” nor my “Maintenance Required” light come on when I turn the key or try to start her. I replaced the relays and still noting. I added two more grounding cables on to the motor and one to the body. Still have to leave the key in the on position until the relays start to tick at which time the “Maintenance Required” lights will flicker in sync with the relays ticking. Again I had to reposition the distributor to get her to stay running and reposition after she warms up.

I thought maybe I have a bad contact at the ECM so I removed the unit cleaned the contacts and greased them again, I also did the same thing to the fuse block connections at the firewall since I was already there. Issue still remains.

I am thinking about replacing the distributer in hopes of curing the repositioning issue, but I am at a loss as to what to do to about the 20 minute wait until the relays tick. Any help would be appreciated, thanks.

Blackjack93 10-19-2012 02:12 PM

you might take it into say Auto zone and have them put a reader on it to see if a code comes up. The ECM may also be going bad?

1SAS 10-19-2012 04:10 PM

It sounds like a bad ECM or a bad ground, which would throw the ECM off. The problem is usually if the ECM goes out, it doesn't throw a code. The ECM is all about thresholds through the electrical sensor inputs. As long as the signal is this strong for this length of time, no problem... but if you have intermittent signals because of a bad ground, you could be in trouble. I would check your grounds, but go through it systematically. Physically grab hold of them and try to move them. If anything looks fishy, repair it. If it isn't the problem, then you just prevented a whole lot more future problems.

If you replace the ECM before you do check all your grounds, you may be creating the same problems again. Good luck with it.

Take care,

Tyewilly 10-20-2012 06:50 AM

The capacitors have burnt up in your ECM. If you're handy with electronics, they can be replaced for a few dollars, if not, you'll need an ECM. Search for "crash course in brain surgery" and you should be able to find a link to a write up on how to fix the ECM to see if you feel comfortable trying it.
As for the distributor, it would probably be a good idea to replace it. The distributor houses the cam position sensor, and it has to be in sync with the crank position sensor for the engine to run correctly (or at all). Replacing it is the only sure way it won't cause you any more trouble that has you chasing your trail.

DaggersEdge 10-21-2012 09:45 AM

Thanks everybody!
Thank for the help everyone. You all confirmed what I thought was the culprit. I confirmed all my grounds are good plus the addition of the two I installed last week, I have ruled out a grounding issue.

I did look at the ECU capacitor replacement tread and I’ll be trying that this week as it is definitely a cheaper repair then buying a new ECU.

I have already ordered a new distributor as I was able to get a complete unit with cap and rotor button for less than $55 on eBay.

I let you all know how it works out,

Thanks again!

DaggersEdge 10-21-2012 02:29 PM

ECU Repaired
Well I had some free time today so I when into town and got the rosin solder, the capacitors, and clear silicone sealant; total cost around $9.00. I took my time and spent around 45 minutes to remove the ECU, replaced the caps, seal the unit and reinstall.

I followed the thread below to walk me through the repair.

Turned the key and all the lights lit up, and she fired up, but stalled. I remembered that I had the distributor turned back for the cold start issue I spoke about earlier. I set the distributor to the position I usually have to set it to for warm start and run then she fired right up. The real test will be tomorrow morning after she sits all night, if she fires right up then the timing issue was the caps in the ECU as well.

I guess I should have repaired the ECU before buying the new distributor that I ordered yesterday, but I can always resell it once it comes in.

I'll update if the timing issue is resolved without the distributor or not.

Thanks again everybody!

95YamJam 10-21-2012 03:52 PM

I did mine a couple weeks ago and mine runs better than ever.

goozslyr 10-21-2012 04:42 PM

I had a similar issue with stopping and starting, I too changed everything sensor wise and cleanen the ECM contacts and added new ground straps. Then took it in they could not figure it out so I emailed chrysler. they said with the old ECM;s if an ignition code comes up no matter what you change the ECM will still think it is bad unless you disconnect the battery and not just positive or negative you need to take off both cables and touch them together to drain the capacitors this is called "FLASHING" the ECM. some of the quaility hand held scanners like mine a MATCO with do this for you when you read and clear codes. jeep has been fine since.

95YamJam 10-22-2012 05:59 AM

Mine did have bad caps. I checked the capacitence on my meter. They were both are out 150 micro farads vs the 220 they should be close to. When i took a heat source to the bad ones the values increased back to around normal but within a few minutes were back down to around 100.

DaggersEdge 10-22-2012 08:51 PM

Running Great
Well I looks like the capacitors fixed all of my issues she starts and runs perfect.

Thanks again to everyone for their advice.


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