joe976

Just bought this vehicle. Runs great for about 20 minutes, then stalls and the engine light flashes rapidly while all the relays in the fuse panel in the engine compartment click. Can also hear the fuel pump operating in time with the engine light flashing, but it will not start. After 10 or 15 minutes, it will start back up, and repeat this stalling out again. My question, will the fuel pump heat up and cause this? Also, I did run it until it stalled and unplugged the fuel pump at the tank, but that did not stop the relays from clicking or the engine light from flashing fast. Lost on this one.. Any advice will be greatly appreciated

dave1123

Welcome to CF!

Just for ***** & giggles, plug a voltmeter into your cigarette lighter socket and watch the system voltage as it starts to falter and the lights flash. I can bet as it heats up, you're loosing power in the system supply wire because of a poor connection. This is the smaller of the 2 wires that come from the battery, the one that goes to the relay/fuse box under the hood.

joe976

Thanks dave1123. Your suggestion prompted a few attempts at troubleshooting this issue, including a new battery and cables installed, taking apart the fuse/relay panel under the hood and cleaning all the electrical connections, the same action taken with the module behind the coolant reservoir. If I am not mistaken, that is the PCM? I wonder if that has **** the bed, as the same problem occurred after those repairs. BTW, not sure if it is related, but also have no radio, VIC in console or overhead, and no AC. If I remove the 30A fuse for the engine control from the relay/ fuse panel under the hood, it does stop the haywire everything clicking stuff, just won't start of course.... Thanks again

dave1123

Okay, There is one other thing you might check. Somewhere around the time of your jeep's build, they started using lead-free solder. The problem with that is the solder tends to be brittle and connections crack. Don't condemn the PCM until you check it for solder cracks. They usually happen on the terminal connections inside the PCM where the terminal strips connect to the circuit board. Sometimes just a little time with a soldering iron can save them. I'm not saying this is your problem, it's just a common problem with jeeps. I would check this before buying a replacement PCM.

One way to diagnose this is to wiggle the cable plugs while the engine is running and see if you get any kind of change in it's running. There are YouTube videos about how to fix this and/or replace the capacitors.

This problem seems to be temperature related and electrical in nature. These are hard to diagnose long distance with a keyboard, so I'm just giving you places to start. Keep us informed what you find because it may help others. I'm sure this problem has come up before so maybe we can get someone else to chime in.

joe976

Will do. I did wiggle that connector, and the idle dropped off, which is why I was asking about the PCM. I will look into self repair, and post rsults when I have them. Thanks for the advice.

joe976

Here is what I did, what I found that I believe was the problem, and the outcome. I removed the PCM and noticed that the gel around those 3 capacitors was cracked and pulled away from them. So I decided to replace them. I followed the directions found at http://www.jeepforum.com/forum/f13/f...riteup-501951/ while doing this. I also cleared all the gel around the main connector and resoldered each of those joints. What I found while removing the caps, was that one had a leg that was broke loose inside the cap, as in it just fell out after removing the cap. I feel that was most likely the issue, as the vehicle has ran non stop for an hour and half now, and still going. I still have a long way to go in re installing everything that was removed while trouble shooting, and because of my choppy soldering skills, I will most likely purchased a reman PCM, I am quite happy about the results. Thanks again dave1123 for your advice.

dave1123

Very good! The reason for the gel is to stabilize the components against vibration and to act as a heat sink. Drying out and cracking allowed the cap to vibrate and break a lead. Most of the time, the capacitors will charge slowly and cause delayed starting or dying after they get hot.

I'm glad you found the problem and I'm happy to have helped. Keep 0n Jeepin'