Need Help on a starting issue YJ ( a nuckle head mistake)

tcobra

tcobra

Member
Joined
May 7, 2015
Location
hickory
I have a 91 wrangler YJ with a 1998 TPI 350 in it the jeep and electronics has been upgraded.custom wiring and all computer o2 sensors the works. Needed a heater core put in no big deal (wrong) lol a buddy said he would help and we would go riding Friday night in the snow ok knows his way around motors no big deal. Here is what happened he disconnected the battery and we started to work parts place gave me the wrong heater core no surprise went back got correct one before they closed we were finishing up and I was putting the glove box back in he asked want me to hook up the battery ya go a head he did I started the jeep and it was setting there running fine for 10 min was putting tools up waiting for the heat to start and the jeep quit just like you turned it off tried to start it would not crank motor spinning over. So here is what happened after a day of trying to figure this out By mistake my friend had hooked my charging wire from my alt to the neg side of the battery. Just glad it did not explode!!!!!! can not find any blown fuses get fuel get power to the dist. getting fire to spark plugs and will not start even if I spray start fluid in it. LOST any ideals sorry for being long winded just trying to give all the details. (could it be the computer and how or where can I get it checked??
 
How can it not start with starting fluid but have fire at the plugs? Are you 100% sure the plugs are firing? What's your fuel pressure?
 
You lost me a sec, so you cannot get fuel or spark, or you do have fuel and spark?
Hard to understand.
 
I've seen a few issues where I've had spark that looked fine, until we replaced the coil and seen how the spark was really supposed to be. Sometimes weak spark will not start an engine.
 
I have fuel and spark thought about fuel pressure but if that was it would it not crank with start fluid I get 12 volts coming from the switch it is a hei dist. Will check ohms res on coil and will report back wonder what the volts should be on a firing plug thanks guys for the reply's
 
tcobra said:
I have fuel and spark thought about fuel pressure but if that was it would it not crank with start fluid I get 12 volts coming from the switch it is a hei dist. Will check ohms res on coil and will report back wonder what the volts should be on a firing plug thanks guys for the reply's
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Threw fuel pressure out there just because you said you checked spark. Ohming out a coil isn't going to show you purple spark at the plug. Plus this is a batch Fire EFI it'll have a very faint spark fired to clear the exhaust. I'm pretty sure it's an ignition related issue. Normally the ignition control module and distributors are to blame. But if you've got injector pulse and spark you can rule out your ECU/ECM
 
thank will try the module I was thanking that might be the problem just when I was turning it over and I was get readings on my volt meter strong and weak firing I had ruled that out never thought of a weak spark old thinking if there a spark there has to be fire lol But with compression you do need a strong spark thanks for the advise will report my progress and thanks for the help ever one
 
update spent all day tracing down fuses and putting New module coil .Same issue guess I will pull the computer and ship it off to be checked. Unless some one here can recommend a good jeep mechanic in Hickory NC
 
update got the computer back no issues on it, installed battery for sh** and giggles turned switch dam thing fired run 30 sec or min like a champ then shut off. I know its getting a spark ordered fuel gauge replaced fuel pump relay just checked pressure holds 40lb when it started it was pumping 60lb.It seam after it sets for a couple days it will crank and run for a short period of time then shut off. Going to replace the auto shut off relay it reminds me of a relay getting hot anyone ever had this? I fear that if I have it total rewired I might have the same problem.
 
Update before I send it to the shop hooked up my nod lights, fuel pressure gauge, spark plug tester. Jeeps been setting near a month hooked battery up reached in and she crank and ran after about two spins NOD light pulse steady spark plug spark stead 40 pounds fuel pressure ran close to two minutes then just shut off. Tested volts to injectors getting 12v with key on getting 0.54 v at throlter body. But motor spins but does not have injector pulse, when key is turned on fuel pump comes on have pressure but no spark to plugs or injectors. Did not think to look at rpm gauge when I spin the motor does not look like was working going to check the cam sensor or just change it.

any other ideals
 
I wonder if you have an issue with the computer that is only notable when running a bit, but then after sitting resets itself or something. So when you had it tested nothing showed up, but after running some time comes back. Like a circuit getting hot or something. My best guess. Suck a strange issue.
I'd be curious to swap the computer for trial.

Or the cam/crank sensor, or distributor. Really mind boggling. I can only imagine how you feel. I wish you were closer, if love to check for myself.

Did you check all the relays like you mentioned?
 
when I sent the ECM off it was tested on their test motor no issues or codes. Yes tested all relay's at the point now just start replacing them one at a time there's a week link somewhere.
 
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