This is for a '94 Yj 2.5 liter ECU repair,
Symptoms: turn key but no check engine light but after a few minutes of the key on, you hear clicking and then the check engine/shift light come on and you hear the fuel pump prime and it starts right up.
-I've been dealing with this for about 3 weeks now since the weather has gotten cold. when the problem first arose I thought it was a bad fuel pump so I replaced it and the strainer still same problem. I was really getting fed up with the problem of leaving it and coming back and having to wait 5 minutes before it would start, i searched all over jeepforum for an answer i found sentinel02's thread about checking all the plugs leading to the ECU very complex but informative but i didnt feel like checking all the electrical components. so I either had to send my ECU out to get rebuilt or rebuild it myself so I decided to take it step by step to show in detail how its done, due to the fact that i havn't seen a step by step version of this and also I noticed lots of '94 YJ owners having the same problem.
Small needle nose plyers
Soldering gun(including flux, wire)
x3 220 uf 35wvdc capacitor (radio shack) the stock spec is 25v but 35 seemed to work also.
1. take ECU out of Jeep you'll need to remove the washer fluid container held on by one philips screw on the side and then it just slides right out.
2.now for taking off the ECU disconnect the main wiring harness leading into it using a 8mm socket, when loosen bolt and pull off gently being sure not so break any contacts.
3. once the harness is off there are 3,8mm bolts just undo them and the ECU will pop right off the firewall.
4.Take the cover off by prying at the prongs that hold the lid to the casing.
5.once cover is removed run a utility knife along the edge close too the plastic once you have cut alll the way around gently pull the ECU itself out of the casing.
6. now heres were it gets tricky. locate the 3 capacitors on the top of the ECU
7. After locating them you have to dig out on the underside of the ECU to expose the ballistics encased circuit board. Its a tidious task but it has to be done to get the capacitors out.
8. now that the contacts are exposed take a soldering gun and melt away the factory solder points, have a friend grab the contact on the top side and pull as you melt the solder.
9.After you get them out take the gun and put it were the contacts went through to make a hole for the new capacitors to go through.
10. now its time to put the capacitors in, make sure that the side with the stripe is facing the big metal tower (reference picture)
11.push them all the done and solder them on the other side back in the original place making sure the stripe is facing the correct way.
12. once they are soldered in place take nailclippers and clip the extra wire.
13. take putty or silicon to reseal the holes wait for it to dry and follow the take out procedure in reverse order.
Click Free. Looks good, definitely cheaper than replacing the thing.