Jeep Wrangler Forum

Jeep Wrangler Forum (http://www.wranglerforum.com/)
-   TJ Tech Forum (http://www.wranglerforum.com/f210/)
-   -   Fuel Pump? ECM? (http://www.wranglerforum.com/f210/fuel-pump-ecm-228781.html)

SDWhite 03-19-2013 11:10 AM

Fuel Pump? ECM?
 
I have an 02 TJ with 4.0L engine. Runs flawlessly, when it runs. It will randomly just stop running. No stutter, no bogging, no degradation of power, nothing. Just stops. Cranks right back up immediately when I turn the ignition and goes right along. Until the next time. :banghead:

I had it pretty wet a few weeks ago and was thinking some water MAY have entered the fuel lines but a full tank of gas later and still doing it.

Fuel pump? Electronic control module?

Any help would be appreciated.

tangofox007 03-19-2013 01:58 PM

A failing CPS can cause those symptoms. You might try cleaning and reseating the CPS connector.

SDWhite 03-19-2013 04:58 PM

Help this computer geek out. CPS?

Jerry Bransford 03-19-2013 05:06 PM

CPS = Crankshaft Position Sensor. Mounted high up onto the driver's side of the transmission bell housing where it bolts to the engine, the CPS generates the engine's master timing signal. It generates the timing signal based on notches cut into the flywheel for a manual transmission or flex plate in the case of an automatic. When the CPS isn't functioning, the engine won't run... and the CPS can both go completely bad or intermittent where it can cause a problem like yours.

There is no guarantee your CPS is the root cause of your engine dying intermittently but it'd be the first place I would look as well. After that, I'd probably suspect a different CPS, the camshaft position sensor (on the distributor shaft) which can cause the same problem but is a little less likely to fail than the crankshaft position sensor is.

wwch99tj 03-19-2013 05:07 PM

crank position sensor

edit Jerry is too fast :rofl:

pyrilampes 03-19-2013 06:32 PM

Fuel pump could be freezing. Replace the fuel filter. It could be clogged and the pump gets hot and quits.

Jerry Bransford 03-19-2013 06:39 PM

While fuel filters can get clogged in some vehicles, especially older models, the TJ's lifetime fuel filter has such an enormous surface area that it clogging would be the very last possibility that I wouldn't even consider. Modern fuel filters are no longer like the old small glass-encased fuel filters that easily got clogged up. The TJ's fuel filter can't even be changed separately without also changing the fuel pressure regulator it resides inside of. Not to mention the gas tank has to be dropped to even get to it.

Big Sarge 03-19-2013 06:42 PM

Quote:

Originally Posted by pyrilampes (Post 3525259)
Fuel pump could be freezing. Replace the fuel filter. It could be clogged and the pump gets hot and quits.

"Freezing" but getting "hot" and cutting off???

Anyways..,.,.. Jerry beat me to what I really wanted to post.

pyrilampes 03-20-2013 07:44 AM

Sorry, I forgot that mechanical failures dont happen to fuel pumps. And that old filters never clog.

SDWhite 03-20-2013 08:05 AM

So the general consensus is in this order:

CSP
Fuel Pump

Any tertiary ideas? Trying to avoid taking it to a mechanic.

pyrilampes 03-20-2013 08:26 AM

http://www.wranglerforum.com/f5/tj-error-codes-358.html

tangofox007 03-20-2013 10:13 AM

Quote:

Originally Posted by pyrilampes (Post 3528009)
Sorry, I forgot that mechanical failures dont happen to fuel pumps. And that old filters never clog.

Perhaps you did forget that neither of those conditions resolve themselves immediately.


Quote:

Originally Posted by SDWhite (Post 3523497)
It will randomly just stop running. No stutter, no bogging, no degradation of power, nothing. Just stops. Cranks right back up immediately when I turn the ignition and goes right along.

Try pulling the fuel pump relay while the engine is runnng at idle and note what happens.

BladeMechanical 03-20-2013 10:36 AM

Good luck fixing your problem, please update with any fix, I've been having the same problem for some time and nobody seems to know exactly what the problem(s) are. I have cleaned the throttle body, replaced the TPS, replaced IAC valve, and replaced CPS. I had a local diagnostics shop work on my Jeep, the tech told me that my Jeep only acted up once and when it did there was no communication between my computer and his, makes me think that maybe the computer is going out. No codes. The shop needs to be able to recreate the issue. I've noticed that this problem is more reoccurring when flexing. A tech at a Jeep dealer suggested that maybe a wiring harness is shorting. I don't have a fix yet. Laters,

SDWhite 03-21-2013 12:27 AM

Quote:

Originally Posted by pyrilampes (Post 3528094)

No error codes being thrown. At all.

SDWhite 03-21-2013 12:28 AM

Quote:

Originally Posted by BladeMechanical (Post 3528545)
Good luck fixing your problem, please update with any fix,

I was chatting with a mechanic when you posted your reply. He's thinking a ground as well. I'll be visiting with him tomorrow at a social event so maybe we can narrow it down.

Thanks everyone.

zeprider25 03-21-2013 11:13 AM

Has it died on you on the freeway? I have similar problem with an auto and it'll shut off for .2-1 second and turn back on if on the freeway. If going slow it shuts off and I have to restart it and usually cranks right back up. Happens 2-3x a week

Might be unrelated but I threw in seafoam last oil change and it stopped doing it until I changed the oil again.

BladeMechanical 03-21-2013 01:58 PM

Quote:

Originally Posted by zeprider25 (Post 3533282)
Has it died on you on the freeway? I have similar problem with an auto and it'll shut off for .2-1 second and turn back on if on the freeway. If going slow it shuts off and I have to restart it and usually cranks right back up. Happens 2-3x a week

Exactly the same thing. Seems to be a common Jeep anomaly.

SDWhite 03-21-2013 10:24 PM

Yup. Very similar. I'm still feeling like its an ignition issue. I'm used to good old points, condenser, and coil. So I am not sure where to begin. THat will be another topic.

tangofox007 03-21-2013 11:38 PM

Quote:

Originally Posted by SDWhite (Post 3536130)
I'm still feeling like its an ignition issue.

Quess what is at the heart of ignition control: the CPS.

The simple act of reseating the CPS connector has been known to cure the very symptoms that you report. The CPS generates very little voltage, so a slightly compromised connection can be very detrimental.

SDWhite 03-23-2013 09:47 AM

Quote:

Originally Posted by tangofox007 (Post 3536603)
Quess what is at the heart of ignition control: the CPS.

The simple act of reseating the CPS connector has been known to cure the very symptoms that you report. The CPS generates very little voltage, so a slightly compromised connection can be very detrimental.

Yeah well that's what I get for thinking. I haven't fixed it yet. But I have definitely ruled out fuel.

So... CPS and the PCM relay are next.

But a question. If it was the CPS wouldn't it be throwing an error code?

wwch99tj 03-23-2013 02:30 PM

Not necessarily the wires to my CPS melted on the manifold and it never threw a code, but ran like crap

BladeMechanical 03-27-2013 11:38 AM

I spoke with a Cherokee owner Saturday, she told me that her rokee had the same exact issues I have described, she replaced and serviced everything I did as well as replacing the ECM, I turned out to be a shorting ignition switch. I will inspect this weekend; hopefully I'll find an issue, finally. Laters,

Morris4x4Center 03-27-2013 11:52 AM

Quote:

Originally Posted by SDWhite (Post 3528049)
So the general consensus is in this order:

CSP
Fuel Pump

Any tertiary ideas? Trying to avoid taking it to a mechanic.

I doubt it is a fuel pump issue, because your saying its abrupt. Fuel pump would create some bucking or signs of failure. Good chance its the CPS / Ignition issues

SDWhite 04-12-2013 10:56 AM

Well... this is what I get for not listening to the experts. It finally threw a code and guess what. CPS. Thanks guys, sorry I didn't trust you.

Advance Auto parts... 35 bucks. 15 minutes work. Runs like a spotted ape.

mrk130 04-12-2013 11:10 AM

Glad you were able to fix it. I'll keep this in mind should I ever run into a similar issue.

SDWhite 04-12-2013 12:48 PM

The uniquness of the situation as I described it makes sense now. It simply loses fire to the plugs and its immediate. No running like crap, no studdering... just OFF. Turn the ignition off and back on and it fires right up.

I thought fuel but as described about if it was a fuel issue, there would have been crap running before and maybe after.


All times are GMT -5. The time now is 10:09 PM.