Solved: Jeep died on me tonight, now won't start

[GregBelleville]

Quick bit of background before I describe my problem.

I bought a 99 Sport 4.0 automatic in September with 190k miles. The car died on me on the way home from the purchase, turned out to be the fuel pump which my mechanic replaced and she's been running fine for last couple months of ownership.

Fast forward to yesterday, on the way home from work, the engine sputtered, one loud backfire and then died. I came to a stop, and she started back up and drove fine for about another mile, then stalled again at a stop light, but started back up and I was thankfully able to make it the final mile home. No CEL by the way. When I got home I left the engine running and poked around under the hood, but nothing obvious from a visual inspection, then the engine stalled again, but now I can't get it to start again. Engine cranks, but won't fire.


I did some searching here on the site and have found a few guys with similar threads that indicate a few possible causes:

1. Fuel pump
2. Crankshaft position sensor
3. Camshaft position sensor

For now I'm assuming it's not my 2 month old fuel pump, so I'm thinking the 2 most likely causes are the crankshaft and camshaft sensors. My plan at this point is to locate both sensors and disconnect/reconnect them to see if either one has a bad connection. If that doesn't resolve the problem, I'm thinking I'll need to buy replacement sensors? Does this sound like a good plan to you experts? Is there anything you guys would recommend I also try that I don't have listed above?

 

[C.J. Roberts]

When you replace the sensors, ONLY use Mopar sensors. Auto part store sensors don't work reliably.

 

[GregBelleville]

When you replace the sensors, ONLY use Mopar sensors. Auto part store sensors don't work reliably.

Thanks for the recommendation, I already started looking, but an having a hard time finding Mopar sensors, do you have any recommendations for a good Mopar part source?

 

[C.J. Roberts]

Thanks for the recommendation, I already started looking, but an having a hard time finding Mopar sensors, do you have any recommendations for a good Mopar part source?

If you get lucky you can find them on ebay. There are places like https://www.wermopar.com. Or rockauto.com.

 

[sab]

Do you know what brand fuel pump was installed? Do a search on here, and you'll find that store-brand fuel pumps are notorious for failing quickly. Bosch seems to be the go-to brand, but they can be hard to find. As for the sensors, you'll have a hard time finding new Mopar-brand sensors because they've been discontinued for quite some time now.

If the fuel pump failed, it's easy to verify by checking fuel pressure (assuming that you or a mechanic have a gauge). As for the sensors, if they fail, they'll usually cause the PCM to set a code (but not always).

 

[buildbigboats]

Had a similar sequence of events happen to me recently. Put in new fuel pump (Delphi). Ran great for about 2-3 weeks then just died as I was turning into a parking lot... luckily. No codes. Nothing but cranking over. Turned out to be broken wiring from previous owner repair that I didn't know about. Patched it in the parking lot, got home and did proper solder/new wire repair. 2-3 weeks later died again. Able to get it running well enough to get home. Cranked and had spark so figured it had to be fuel. No codes. For the hell of it... after thinking I really didn't want to drop the tank again... I picked up new fuel pump relay and that did the trick. Checked fuel pressure and it's 61psi (2006) so good there. Check fuel elctrical system completely.

 

[old jeep new to me]

Sounds like what I had going on about 6 months ago. I can never remember which sensor it is but it was the one by the flywheel on the transmission.

 

[GregBelleville]

Do you know what brand fuel pump was installed? Do a search on here, and you'll find that store-brand fuel pumps are notorious for failing quickly. Bosch seems to be the go-to brand, but they can be hard to find. As for the sensors, you'll have a hard time finding new Mopar-brand sensors because they've been discontinued for quite some time now.

If the fuel pump failed, it's easy to verify by checking fuel pressure (assuming that you or a mechanic have a gauge). As for the sensors, if they fail, they'll usually cause the PCM to set a code (but not always).

Thanks, not sure what brand pump was installed, but I'll plan to get a loaner fuel pressure gauge from auto zone to test whether there may be an issue with the new pump.

 

[GregBelleville]

Sounds like what I had going on about 6 months ago. I can never remember which sensor it is but it was the one by the flywheel on the transmission.

From the research I've been doing that sounds like either the crankshaft position sensor or the camshaft position sensor, both I believe are located near where the transmission attaches to the engine.

 

[GregBelleville]

So update. it's Saturday, Jeep has been sitting since Tuesday. It fired right up this morning, I let it idle for about 10 minutes, no issues. I decided to try and drive it up to Autozone to have them check for any codes, for some reason my cheap OBD scanner isn't seeming to read or connect w/ any of the ports on my 3 cars. I also wanted to get a loaner fuel pressure gauge while I was there to test fuel pressure to rule that out.

Anyway, I get just barely out of my neighborhood, maybe a 1/2 mile and it dies and now won't restart.

I had a buddy tow me back home and in the driveway I wanted to test whether I had spark as I saw on a youtube video that if I have no spark, that that's a symptom of bad crankshaft position sensor. So I pulled one of the plug wires, stuck a philips head screwdriver into it and held it close to a bolt on the alternator while my buddy cranked the motor. I did not have any arcing from the screwdriver to the alternator bolt, so it appears I have no spark.

I received a Necklin(?) crank sensor yesterday, so I swapped that out, and still no luck when I tried to start it, so it appears the crank sensor wasn't the cause of my problems. I still haven't measured fuel pressure, but I can smell gas while cranking, and was able to purge a bit at the fuel rail.

Anyone have ideas on why the intermittent start after sitting a couple days? I still haven't tried replacing the camshaft sensor, but pulled it out today and unplugged it, and didn't see anything obviously bad, so I put it back in, tried to restart car, but still no luck...so I may look online for a CPS.

 

[GregBelleville]

Just wanted to close the loop on this thread I started. The problem ended up being a bad connection to the ignition coil where it connects to the PCM connector.

By simply pulling the connector apart and plugging it back in was all it took and the Jeep fired back up. Once I realized this was the cause I pulled it back apart and cleaned it with a tooth brush and contact cleaner.

 

[sab]

Just wanted to close the loop on this thread I started.

Thanks for doing that! More often than I'd like, I encounter threads on here that would be very helpful if the OP would have updated the thread with the resolution. Kudos to you!

 

[GregBelleville]

Thanks for doing that! More often than I'd like, I encounter threads on here that would be very helpful if the OP would have updated the thread with the resolution. Kudos to you!

I share that sentiment, especially after going down the crank/no start rabbit hole when I was researching possible causes and seeing quite a few threads that ran to a dead end and the OP never confirmed the actual fix for the problem.