Okay I'm new to the forum and also kinda new to the jeep world. I had one back in the 80s so it's been a while. I recently traded for a 99TJ and I knew it needed some work so here's what it does. When you go out and start it in the morning it won't turn over twice until it fires right up and you drive it come back home shut it off and it won't start back wait a couple hours and it'll fire back up. Checked the firing and it wasn't firing so I put a CPS on it and that didn't help so I went ahead and put a coil on it and that didn't help still the same thing start and drive until you shut it off and it won't start back. Any suggestions would be greatly appreciated. Thanks.
Won't start after driving
- Thread starter Kyredneck
- Start date
Search around in this forum for heat soak. Not saying it’s your problem, but there is a lot of people having similar issues. Use the spy glass top right, and the google option. Good luck, you are in the right place with a lot of smart TJ owners.
If nothing else, it will bump this back to the top.
If nothing else, it will bump this back to the top.
Could be heat soak as DYT said.
Could also be leaky injectors.
Or vapor lock (but this would fall under the "heat soak" category).
If you are still running OEM injectors I'd just replace them anyway. They're cheap and easy to replace. If the problem persists, I'd move to making sure you are getting enough cooling flow:
- Is the radiator fan clutch bad?
- Is the radiator dirty / clogged?
- Do you have a hood liner that you really don't need?
- Other misc debris in the general area of the engine
Could also be leaky injectors.
Or vapor lock (but this would fall under the "heat soak" category).
If you are still running OEM injectors I'd just replace them anyway. They're cheap and easy to replace. If the problem persists, I'd move to making sure you are getting enough cooling flow:
- Is the radiator fan clutch bad?
- Is the radiator dirty / clogged?
- Do you have a hood liner that you really don't need?
- Other misc debris in the general area of the engine
Before you try to start it the next time, try this and see if it makes any difference. Cycle the ignition switch on-off-on 8-10 times, holding it in the On position 2 seconds for each cycle. Then try starting it. Did anything change? If it starts right up right after doing this each time you have a bad fuel pump.
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Sounds like the later intake manifold injector heat soak issue to me, since it won’t start immediately after it’s been running but will start later after it had cooled down. I would do the Mopar TSB and see if that fixes it.
Before you spend any more money on parts that are not needed do a little investigating.
When the engine will not start after a drive determine what is missing to start the engine.
Is it fuel as JB posted or is it spark or is it the control circuit such as a relay...
Remove a spark plug wire and determine if you have spark while cranking the engine.
When you turn the ignition to ON, but not START; do you hear the fuel pump come on for 3-5 seconds ?
Check the Automatic Shutdown and Fuel Pump relays for proper operation; old relays that overheat may not work properly causing a no start situation until they cool down.
When the engine will not start after a drive determine what is missing to start the engine.
Is it fuel as JB posted or is it spark or is it the control circuit such as a relay...
Remove a spark plug wire and determine if you have spark while cranking the engine.
When you turn the ignition to ON, but not START; do you hear the fuel pump come on for 3-5 seconds ?
Check the Automatic Shutdown and Fuel Pump relays for proper operation; old relays that overheat may not work properly causing a no start situation until they cool down.
Don't go replacing anything until you determine the root cause of your problem.
Heat soak is for the #3 injector and will not cause a no start. It will cause an extended crank and rough idle for a few seconds.
99 TJ should have the schrader valve on the fuel rail, so you can put a gauge on it to check fuel pressure.
Running pressure should be 49psi +/-5psi. Shut the vehicle down and verify the pressure doesn't drop to below 30psi for 5 minutes.
This will tell you if you have a faulty check valve or a leaky injector. Your fuel pressure will eventually drop to 0 psi.
You need to determine what you are loosing, spark or fuel. A noid light comes in handy to see if you are loosing injector pulse.
Inspect the wiring behind the valve cover. also check the wiring going to the crank sensor.
Follow what @CharlesHS and @Jerry Bransford suggest.
Heat soak is for the #3 injector and will not cause a no start. It will cause an extended crank and rough idle for a few seconds.
99 TJ should have the schrader valve on the fuel rail, so you can put a gauge on it to check fuel pressure.
Running pressure should be 49psi +/-5psi. Shut the vehicle down and verify the pressure doesn't drop to below 30psi for 5 minutes.
This will tell you if you have a faulty check valve or a leaky injector. Your fuel pressure will eventually drop to 0 psi.
You need to determine what you are loosing, spark or fuel. A noid light comes in handy to see if you are loosing injector pulse.
Inspect the wiring behind the valve cover. also check the wiring going to the crank sensor.
Follow what @CharlesHS and @Jerry Bransford suggest.
In what way is a fuel pump spring loaded check valve related to a no start after driving condition?
The fuel rail pressure is bled off due to the leaking check valve.
The engine may start, but will stumble until the fuel pressure is pumped up.
I don’t see why that problem would happen then but somehow be better hours later when it starts again.
I am just answering your question as to why and explaining how it could happen; not that it is happening.
Please read my response in Post #7.
I understand how the fuel pressure system works with the check valve and how you will get long starts if that pressure starts bleeding off more than it should. I was mainly asking William why he’s pushing Jerry’s advice when I don’t see how it is relevant to this scenario. I’m thinking Jerry mistakenly interpreted this post when he said that because he usually wouldn’t recommend that for this. Usually the fuel pump check valve is only considered when you get long choky starts that are cured by priming a few times with the key. That same problem won’t be any better 2 hours later than it would be the minute you shut the rig off from driving and try to restart so I don’t see how it’s relevant. That is all I’m getting at.
It's not. but it is part of strategy based diagnostics of the fuel delivery system. A stuck check valve won't lead to a no start condition and neither will heat soaked injector as others have suggested. It will lead to an extended crank, a few seconds, not hours as the OP is experiencing.
A fuel pump that is beginning to fail can cause the concern. They get hot. The vehicle gets shut off and it will not restart until the fuel pump cools down. I've replaced numerous fuel pumps for this condition.
I could give you a dozen other scenerios that may be causing his condition
Internal pcm failure when hot
Bad ASD relay
Fuse box issue
corrosion or water intrusion in a connector, causing high resistance in a circuit.
First let me say thanks for all the replies in really appreciate it. It's missing fire after it warms up won't show any spark whatsoever. I've checked every fuse they're all good. Ill look at dinner of these other options in the next day or so and I will keep you guys updated to the problem. Once again thanks for all the suggestions it gives me other things to look at.
Let me add it shot some ether in it and it won't fire at all when it's warm so I don't think it's the fuel pump it's just getting zero fire.
Heat soak in the TJ's 4.0 does not usually cause a no-start condition, it normally just causes a misfire at the #3 cylinder. My above suggestion is simply part of a troubleshooting procedure that takes less than a minute and zero cost to try. Especially since you have already replaced the CPS and ignition coil.
Well I can definitely say the radiator needs flushed like immediately which that was the first thing I was gonna do as soon as I got it running but it's bad he said he put a new radiator in it a few years back and hasn't flushed it since but could that be the problem? I've drove it maybe 30 miles since getting it just trying to diagnose the problems it has and the temp hand stays a notch below 210 but you hear it bubbling after shutting it off. I do know he's drove it for about 4 years and never had a problem like this whatsoever until about 2 months ago and then I traded him out of it about a month ago but it had quit on him like 2 or 3 times in like the month prior to me getting it and that's when he decided to get rid of it.
Just to give everyone a update it ended up being the pickup coil. It was rusted over don't ask me how it got that rusty inside the distributor but it did. I really supervise all your help and suggestions. Thanks