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1990 MJ No start when hot


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Hey guys, i just started having this issue with my '90 mj. Was running fine up until maybe a week ago, the jeep will start right up while cold and run until you turn it off. If you let it get hot and then turn it off it won't turn back on without spraying some starter fluid in the intake. Can't figure out where the problem is. Checked and cleaned all my grounds, replaced the CPS and TPS, new o2 sensor. We looked at the coil with a light and the coil glows, but then as the engine goes down in rpm the light begins to more or less flicker and pulse with the distributor. I'm not sure if thats normal or not. My current plan of attack is to replace the coil, Distributor, and possibly the coil driver. Any other ideas? 

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Quit firing the parts cannon at it first of all. It starts with starting fluid when hot, right?

That rules out CPS, TPS, dizzy, O2 sensor which you have already replaced. Dizzy doesn't know if you're spraying starting fluid into the throttle body...

 

I'm thinking there's a problem with fuel delivery. Fuel pump relay, ballast resistor?

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Quit firing the parts cannon at it first of all. It starts with starting fluid when hot, right?

That rules out CPS, TPS, dizzy, O2 sensor which you have already replaced. Dizzy doesn't know if you're spraying starting fluid into the throttle body...

 

I'm thinking there's a problem with fuel delivery. Fuel pump relay, ballast resistor?

 

Trust me, if I didn't have to put the parts on i wouldn't. The distributor it has is going bad, it started with a quiet ticking noise like a lifter click but has gotten way louder so I'm replacing that today so i don't hurt anything else. It has a new ballast resistor as well. I'm starting to think maybe fuel as well. I had it out last week and it stalled on me twice from no fuel, we played around with it and found the fuel pump relay had gone bad so we replaced that and it started right up. Figured that was the fuel issue but I'm starting to wonder now.

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Quit firing the parts cannon at it first of all. It starts with starting fluid when hot, right?

That rules out CPS, TPS, dizzy, O2 sensor which you have already replaced. Dizzy doesn't know if you're spraying starting fluid into the throttle body...

 

I'm thinking there's a problem with fuel delivery. Fuel pump relay, ballast resistor?

 

Trust me, if I didn't have to put the parts on i wouldn't. The distributor it has is going bad, it started with a quiet ticking noise like a lifter click but has gotten way louder so I'm replacing that today so i don't hurt anything else. It has a new ballast resistor as well. I'm starting to think maybe fuel as well. I had it out last week and it stalled on me twice from no fuel, we played around with it and found the fuel pump relay had gone bad so we replaced that and it started right up. Figured that was the fuel issue but I'm starting to wonder now.

 

Go to www.cruiser54.com and read about dizzy indexing

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Quit firing the parts cannon at it first of all. It starts with starting fluid when hot, right?

That rules out CPS, TPS, dizzy, O2 sensor which you have already replaced. Dizzy doesn't know if you're spraying starting fluid into the throttle body...

 

I'm thinking there's a problem with fuel delivery. Fuel pump relay, ballast resistor?

 

Trust me, if I didn't have to put the parts on i wouldn't. The distributor it has is going bad, it started with a quiet ticking noise like a lifter click but has gotten way louder so I'm replacing that today so i don't hurt anything else. It has a new ballast resistor as well. I'm starting to think maybe fuel as well. I had it out last week and it stalled on me twice from no fuel, we played around with it and found the fuel pump relay had gone bad so we replaced that and it started right up. Figured that was the fuel issue but I'm starting to wonder now.

 

Go to www.cruiser54.com and read about dizzy indexing

 

 

Over the weekend we replaced the distributor and it's running a bit better now. The original one was so loose that the little arm inside was so loose that if you lined it up with the firing pad it could move in front of or behind it with hardly touching it so we think it was firing slightly advanced at certain times and running "good" and at other times the spark was retarded making it have small backfires. Now you can rev it without it backfiring like before. We still think it's having a problem with fuel, going to check pressure tonight and then replace the filter

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Progress.

 

Seems to be a bit of progress. Filled her up with some premium gas last night and she was running way better and was starting hot so it looks like (knock on wood) that problem is out of the way. On start up she's really strong and then slowly starts to choke it seems like. I I'm going to take a video of what i mean when I get home tonight. It will be idling at around 600-800rpm really nicely and then drop down to almost 200rpm and kind of go back and forth between 200-600 and almost stall, then it will catch itself and rev itself back to 800 and start the cycle over again. Also if you rev it real quick and let go it stalls 90% of the way and then starts up again. We still can't figure out that issue

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More progress, we're narrowing all the issues down, two things that happened after we got the new distributor in. 1, Jeep kept dying over night, found alternator is bad so thats a known issue I haven't changed out yet but we had it running and took it for a drive around. 2, coil is not constantly firing on start up. If you bump the key over and watch it with a light it will flicker twice and then not fire. If you wiggle the key around a bit and then try it every other time it might fire, it might not. I just replaced the coil and coil driver so both are new. We're thinking it's the ignition switch. Just like the coil firing, sometimes you'll hear the fuel pump go off, some times it won't. We're really thinking the ignition switch isn't providing the 12v to turn on the coil and fuel pump.

 

Also, If you do get it started and put it into gear, it usually stalls out unless you give it gas while changing into gear

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