Here's the deal. YJ/89/258/ 5spd. Drove to work. Parked it. Never started again. Yanked engine (was in sad shape), dropped a better 258 in. Still won't start. New cap,rotor, plug wire, plugs. Nothing yet. Turns over fine. Got plenty of spark and fuel going in but won't catch. Completely baffeled! Tried to pull start it. Still won't catch. Wiring inside the engine compartment isn't in awesome shape. Any idea what is preventing it to start? Is there a sensor or a wire that could prevent the whole thing from starting? Please help as we've been working on this thing forever now!
Fuel is getting into all cylinders fine. I don't get it. Logically, Fuel in cylinder, spark in cylinder, good compression, explosion, no? Not in this case...
pretty sure the timing's fine. We swapped the cap/rotor twice but don't think we screwed up the timing. I'm pretty sure it has something to do with the wiring harness in the engine but I can't figure out what that could have to do with it not starting...
The wiring harness is not going to keep the engine from starting if you have spark and fuel already. If you have spark and fuel, either the spark is at the wrong time, or some thing is mechanically wrong. Possibly the timing chain is off.
Since the engine is cold, the fuel system would be in open loop, so the carb stepper motor goes to one stetting and stays there.
It would be a good idea to check and see if it is moving at all.
They can get filled with crude and stick in one place.
But I doubt this would keep you from starting.
I would bet the distributor is 180 out. Double check that it is set up on cylinder #1 TDC compression.
Do a search for a nutter bypass and make the mod on your distributor. It will take the YJ computer out of the loop. A YJ also has an ignition module under the wiper fluid fill bottle. This might be your problem. There are also several fusable linkes on the starter relay below the battery on the fire wall. HTH.
The old 258 I had's compression (on it last day) was about 120 all around except 1 cyl which was at 60lbs. This newer 258 has 125 to 126 all aound so I don't think it's that.
Driving me nuts! (no pun intended) It must have something to do with the harness. We cracked it open yesterday and there was a meldown at some point in time. Few wires completely melted. Just trying to figure out how this could stop it from firing up and which one is causing the problem.
Now this opens up a whole new can of worms
if the harness is repairable, do so before wasting time trying to start the engine.
If not repairable, swap in a new harness. Check for blown fuses at the power distribution module.
I am starting to question if you are getting fuel or spark like stated earlier. That is all the harness is going to control. If the harness is damaged, it may NOT HAVE FUEL OR SPARK OR BOTH!
Well, I'll be working on the harness tonight and possibly tomorrow. There is SPARK. Got a shock testing it. It's there and it's strong. Fuel, I can see it going into the Carb. I pulled the plugs out and they're a tad wet (with gas)...
Gonna have to see what the harness will give me I guess...
I have heard that if the computer goes out that you are basically dead in the water. Sounds like it rarely goes out but have you replaced? might be worth a try.
Swapped computer and carb, plugs, cap and rotor 2 times to no avail. The computer your refering to is the one controling the carb or the one controlling the ignition?
I think I'll try the Nutter bypass tonight and see what comes out of it...
An engine need three things to run, fuel, spark, and air, you say you have fuel and spark, maybe you're not getting any air? Did you foget to metion that you're working on this Jeep on the Moon? Sorry about that, my vote is for either spark at the wrong time, or bad fuel.
how about the air/fuel mixture adj. have a friend who left his all the way in after a rebuild,bitched for weeks untill he gave up and put a 4.0 in. then he figured it out.
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