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Starts but wont restart untill completely cool

2K views 16 replies 12 participants last post by  Que89YJ 
#1 ·
I have an engine that starts and run good but if I shut it off even for a second it will not restart untill the engine is completely cooled down. Any ideas?
 
#2 ·
Starter won't operate, or the engine won't start up while engaging the starter?
 
#4 ·
the haynes manual says. 1. air filter clogged. 2. fuel not reaching injectors because of vapor lock, brought by clogged fuel tank vent line. 3. bad engine ground. 4.defective pick up coil in the distributor 5. defective crank position sensor (CPS) hopefully this will help ya out man
 
#6 ·
I've had similar symptoms a couple of times and fixed it with a new TPS. In both cases for me, the jeep would run well until it switched over to "closed loop" operation, then it would hesitate and die & wouldn't restart until it cooled enough to run in "open loop" mode.
 
#8 ·
If it starts cold fine AND runs hot fine but won't start hot then it has to be something heat related that isn't effectivly cooled while the engine isn't running.
How long do you have to wait? does opening the hood help?
My first guess would be that somewhere between tank and engine your fuel line is getting too hot and your vapor locking. While it's running you are getting cool fresh gas through the line but once the pump stops the gas is boiling where ver the heat source is...or that's my guess.
Trace your fuel lines look for somewhere that it touches or is at least very close to exhaust.
 
#9 ·
Just had what sounded like the same problem. But without cranking. Nothing. Dome light works. Sounds like fuel pump fires, but nothing else. No cranking at all.
It's happened now twice. Both times the YJ started fine. Went to get gas. Shut it off. Then it was 'dead'.
No electrical at all. 1st thought was to put it in/out of Park. Then rock a little to ensure the 'Park' indicator was indicating. But nada.
1) My son simply waited (15 min) & it restarted.
2) A put in 2 quarts of oil and it started.
?? Could there be a condition where low oil (not pressure) would kill electronics? There is something like that for our camper generator, I understand, but that's never happened, as I always check the oil.
Anyone run into this before?
Thanks,
Stan
 
#14 ·
Short drives still make it hot under the hood. When it is in the no start condition do you still have spark at the plugs? Is there still pressure at the fuel rail? YOu need fuel spark and air. If you can figure out which one is missing(All easy test) that will narrow it down alot. Meanmax is here he is one of jeep forums best. He will get you going again.
 
#15 ·
Don't throw parts at it trobleshoot it. Check your codes first:
http://www.jeepforum.com/forum/f12/how-check-fault-codes-1257145/

Next when it happens see where your problem is. Does the fuel pump kick on when you turn the key? Do you have pressure at the fuel rail? Do you have spark at the plugs? Check and see and post back.
 
#17 ·
You don't need any tools for check fuel and spark. Just push the valve on the fuel rail for fuel and hold the plug/coil wire near ground to check spark.
 
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