this is my first post and I want to say thanks to you guys for all the great info on this site. I have been racing dirt modifieds for 10 years and have recently sold out of racing to spend more time at home. I have never owned a jeep before but thought this would be a good way to spend time with my son and still have fun. Well have ended up with not 1 but two 2 yj's haha and so the fun begins. One is a 88 with the chevy small block and a 700r4 and the other is a 95 with the 4cyl. The problem I am having is with the 95 with the 4cyl, when I got it I had to put some wiring back together and I got it running but it was hard starting and ran rough but it ran. I now have pulled it in the shop for paint and body work and to get it running the right way. Now I have no spark at all. To help I will list the checks I have already done to track it down with not success. Please keep in mind I have been building racecars and my own race engines for years and I would say my mechanical ability is an 8 out of ten but with something new comes a new learning curve hahaha.
Performed pin test for ecu and have power and grounds where they should be (great write up from sentinel by the way).
checked all fuses and relays they are all good.
looked at about a million pages of schematics and understand how system works.
Checked resistance in coil primary and secondary voltage, they are within tolerance( secondary was at the max resistance though)
Checked input for cam positioning sensor 7 volts, 5volts, 0.
When the key is put to run the fuel pump primes the rail and then shuts off as normal but what I have it narrowed to and don't understand is there is a geen wire with and orange stripe that comes from the auto shut down relay that powers the hot side of the coil, the injectors and some other sensors. Ok when I check this wire with the key off it is grounded but when the key is turned to run is goes hot until the fuel pump primes and shutoff then it goes back to a ground again. it seems that this wire should stay hot in the run position so there is power to the hot side of the coil but it doesn't stay hot it goes back to a ground after the fuel pump primes and shuts down ?
Even though I am mechanically inclined this problem is making me crazy. any suggestion where to go from here would be greatly appreciated thanks guys.
Fill out your profile. I assume since you are talking about a kill switch that you have an auto trans in the 95, but it's not clear.
I know you have checked for resistance, have you checked for spark at the plugs, and then on back to distributor, then to coil? You need to narrow it down to a spark or fuel problem. My guess is the fuel is ok since the pump kicks on.
Also did the Jeep sit for a long time? If so you may have Ethanol based damage in the fuel system, it's nasty to the fuel rail, pump, sending unit, etc.
I checked for spark from plugs, and then the coil that is what lead me too the supply wires for the coil. Like i said when the fuel pump is priming the green wire from the asd relay to the coil is hot amd when the pump shuts off it goes dead. This may be what its supposed to do but im not sure. It doesnt have a kill switch what i meant to say was key switch.I will update my profile tonite and thanks for the help.
95 yj 4cyl, 5 speed manual.
No not ex navy or military ive never had the honor of seving but am a big supporter of our military men and women.
I havent got any codes as of yet i get no check engine lite when the key switch is in that is why i did the pcu check that i rwad in here. I think the check engine lite bulb is out becaise i have never seen one come on when it did run. The only lights i get are the seatbelt amd the upshift light when i turn the key to start. I did not check for voltave while cranking since i didnt have any power to the hot side of thw coil. Maybe someone can explain how the coil is fed during cranking or not cranking and i can understand a little better on how to check it again. Could this be something as simple as a bad coil haha. Thanks for the help.
The CEL is real important because of a common issue with filter caps failing in the ecu. The fact that you are hearing priming means that it is probable not the issue but due dilligence. if you did sentinels troubleshooting and have power on pins 3 and 9 at the ecu then you need to check that bulb or you can use a test light to check codes. Take a 12 volt test light and hook one lead to positive. Hook the other lead to the wire for pin 32 of the ecu. That is the line that the ecu grounds to light the CEL. It is ground switched. That is why you are hooking the other lead to battery positive. It should act just like the CEL. Post back what you find. I have included a pinout of the ecu. The colors might not match because its a different year but the circuits are all the same. Post back what you find.