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Jeep died/won't start

rwat96

NAXJA Forum User
Ok so yesterday I went to start my jeep and it was cranking over with nothing happening after a minute or two of attempts it sputtered to life and it ran fine the rest of the night and this morning. While on my way to work this afternoon, it suddenly died at a stop light and it took a few minutes of cranking for it it start again, and it made it a good ways but when I let off the gas the engine rpms didn't return to idle but instead it idled high and was somewhat erratic (i cleaned my idle air control valve a few months ago so I doubt that's it). It died once again at the turn into the parking lot, and this time it wouldn't start and a good Samaritan in a truck pulled me into the lot. I haven't had much time to do any trouble shooting but I feel it is either the CPS or a fuel delivery problem. Does the inconsistency usually mean a fuel delivery problem or the CPS? I originally thought the CPS but when I think about it now it may be fuel related as both times it didn't die while idling but instead when I just started to accelerate from a stop. Any thoughts?
 
I doubt it has anything to do with the fuel system. Focus on the spark plugs, plug wires, rotor and cap, spark coil and ICM module all in the spark system, inspect them completely, test them.

What year is it?

Yes, test the CPS, try a hair dry on it while the engine idles to see it cuts out when hot. Follow the FSM test of the CPS also.

Test the IAT temp sensor with an ohm meter versus factory specs at several temps. Try starting it at WOT right off the bat, if it does not start at first, to see if it was flooded.

Check the spark plugs for a smell of raw gas if it will not start, to see if it flooded. A problem with the O2 sensor can cause it to die, but it should not be a no start issue, so ignore it for now.

A sticking IAC valve might be part of the problem.
 
All of that sounds good, I will do as much as I can of that stuff in the lot of where I work. And it's a 1996. but because of this issue of where it is I don't want to tow it and I want to get it running, so clear direction would be great as I can't he dealing with trial and error when I don't have it home with me. So when I got off work real late, I went out to start it and it started right up, but idled rough for a few seconds, but then idled normally after that, when I would Rev it it would sputter and run rough until it got about above about 2k rpm . When I drove it around the lot it would run ok but idle high and it would once again run rough when I gave it any gas, and after giving it some gas while driving it, it slowly sputtered to a stop and it wouldn't start after that What does this sound like to you guys? I would think it's a fuel problem except that it started after sitting for over 5 hours??? And then wouldn't start again? Also the plug wiring isn't factory so I assume the previous owner did maintenance on the ignition system at some point whithin the last few years, so I doubt that's it.
 
I've had fuel pumps go out sporadically so that's where I would start. Check fuel pressure and see if you can correlate the bad performance with pressure fluctuations. You can rent the gauge at autozone in new york, j don't know where you are.. But honestly it's a good tool to own. I would also take the distributor cap off and see if there's any moisture in there or if the rotor looks worn. Have you replaced it in the past or know if the previous owner did? If it's original maybe that's a good place to start too.

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I've had fuel pumps go out sporadically so that's where I would start. Check fuel pressure and see if you can correlate the bad performance with pressure fluctuations. You can rent the gauge at autozone in new york, j don't know where you are.. But honestly it's a good tool to own. I would also take the distributor cap off and see if there's any moisture in there or if the rotor looks worn. Have you replaced it in the past or know if the previous owner did? If it's original maybe that's a good place to start too.

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That would make sense except it still makes noise, I heard priming when I turned the ignition on and I heard it pumping when the engine was running. A bad seal in the pump wouldn't be sperodic would it? Something else i should have added was that yesterday I either ran out of Gas earlier than usual or the pump acted up on me, and it may have run ok when I walked back from the gas station with a can of gas because it has been 30 mins. And would a distributor cut out when power is applied but idle the car ok? I feel like that would affect all rpm ranges especially idle?
 
My dad's volvo had a leak on the cam seal letting oil into the distributor and it idled fine, but driving it, it would randomly miss, as well as stall while moving.

A faulty fuel pump can do a lot too. If you ran out of gas, that can finish off an already worn pump. It can't hurt to check the fuel pressure to know for sure though. Also a bad seal or check valve can cause hard starts and rail pressure fluctuations, at least in other cars I've owned.

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My dad's volvo had a leak on the cam seal letting oil into the distributor and it idled fine, but driving it, it would randomly miss, as well as stall while moving.

A faulty fuel pump can do a lot too. If you ran out of gas, that can finish off an already worn pump. It can't hurt to check the fuel pressure to know for sure though. Also a bad seal or check valve can cause hard starts and rail pressure fluctuations, at least in other cars I've owned.

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That's interesting, that's a possibility but I will defiantly start by checking the fuel system as i could have easily finished off a dying pump. I will finally have time to troubleshoot what's going on this afternoon and I will get a pressure Guage from the autozone across the street and start with that I will let you guys know what I find.
 
Ok so I have got 50psi of fuel pressure, I replaced the cps, and I've got a strong white spark. And it still wont start. I don't know where to go from here? Any thoughts anyone?
 
It's possible you have fuel pressure but no flow.
If you don't have a CEL lit, I'd still suspect it's
fuel related. Spray some starter fluid down the
throttle body and see if it runs for a few seconds.

If it does, then the trouble is either a clogged fuel
filter or bad fuel pump.
 
It's possible you have fuel pressure but no flow.
If you don't have a CEL lit, I'd still suspect it's
fuel related. Spray some starter fluid down the
throttle body and see if it runs for a few seconds.

If it does, then the trouble is either a clogged fuel
filter or bad fuel pump.

Ya I don't have a CEL. And explain how I could have pressure but no flow? while the engine was cranking the pressure dropped 10psi to 40, that should be plenty to run right? And if the pressure dropped but maintained at 40, that means it's flowing right? At least to me the only way it wouldn't flow but maintain pressure is if the injectors weren't working. Idlf you could explain how that could be that would be helpful. :)
 
It may be flooded. Push the gas pedal to the floor and hold it there and then crank it, until it starts for up 15 seconds, for about 3-4 tries. If it is flooded that will cut the injectors off and dry out the cylinders enough for it fire.

Sounds to me like a bad TPS. But reread my earlier post, here is what is left:

I doubt it has anything to do with the fuel system.
Test the IAT temp sensor with an ohm meter versus factory specs at several temps. Try starting it at WOT right off the bat, if it does not start at first, to see if it was flooded.

Check the spark plugs for a smell of raw gas if it will not start, to see if it is flooded. A problem with the O2 sensor can cause it to die, but it should not be a no start issue, so ignore it for now.

A sticking IAC valve might be part of the problem.
 
It may be flooded. Push the gas pedal to the floor and hold it there and then crank it, until it starts for up 15 seconds, for about 3-4 tries. If it is flooded that will cut the injectors off and dry out the cylinders enough for it fire.

Sounds to me like a bad TPS. But reread my earlier post, here is what is left:

I doubt it has anything to do with the fuel system.
Test the IAT temp sensor with an ohm meter versus factory specs at several temps. Try starting it at WOT right off the bat, if it does not start at first, to see if it was flooded.

Check the spark plugs for a smell of raw gas if it will not start, to see if it is flooded. A problem with the O2 sensor can cause it to die, but it should not be a no start issue, so ignore it for now.

A sticking IAC valve might be part of the problem.

Is there a way to test a TPS? And I will look into the inlet air temp sensor. And I will try that, but I don't think it's flooding, it has started before with so much execcisve fuel I can smell it, but I have not been smelling fuel if I recall correctly. And I can re check the IAC but I cleaned it recently so I doubt that's it. And also I read on another forum that the fuel pump is suppost to maintain 50 psi when cranking, mine drops to 40 when cranking, is this accurate and if so will this 10 psi difference prevent it from running correctly or at all?
 
With the fuel pressure gauge connected, does the rail lose pressure quickly, or does it maintain pressure for a while?

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The pressure slowly drops, like maybe 20 psi over a 10 to 15 min period when sitting, so I assets the check valve is on its way out, but that isn't the issue as it dies while running. Or are you referring to something else?
 
Ok so I changed the tps and it finally runs and drives, but it instantly gave me a check engine light (after resetting the ecu by grounding the negative battery connecter to the positive for 30 seconds then turning headlights on and off) and it wouldn't idle right and still wanted to die until the engine ran for a bit then it would idle ok, but it doesn't run quite right and it shifts at 3,000 rpm or so. I replaced it with another tps and the same problem. Is it the duralast tps sensors from autozone giving me greif, or do I have a deeper electrical problem? Also will this clear if I drive it more and give the ecu some time?
 
Is there a way to test a TPS? And I will look into the inlet air temp sensor. And I will try that, but I don't think it's flooding, it has started before with so much execcisve fuel I can smell it, but I have not been smelling fuel if I recall correctly. And I can re check the IAC but I cleaned it recently so I doubt that's it. And also I read on another forum that the fuel pump is suppost to maintain 50 psi when cranking, mine drops to 40 when cranking, is this accurate and if so will this 10 psi difference prevent it from running correctly or at all?

There are several ways to test the TPS, some of them I created, the 87 and 89 FSM has two different ways also. Details on all of them and testing the IAT sensor are here

http://www.naxja.org/forum/showthread.php?t=905849&highlight=renx+files

it is a long read, but well worth it.

IAC valve can be damaged while cleaning, or can just go bad. So do not assume it is OK. Also there is a relay reset timer that works with the ECU to reset the IAC after turning off the engine, that relay can cause problems IIRC.

EDIT!!!! I see yours is 96, not a Renix, so the link data may be different, but the method is the same. You just need a good part to compare to the used, mounted part and you need the 96 FSM that has the proper test data.
 
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I have had about 50 out of 60 parts fail in months if not right out of the box from AZ the last 3 years.

Get a code scanner and check the codes and post them up. AZ will check them for free.
 
I have had about 50 out of 60 parts fail in months if not right out of the box from AZ the last 3 years.

Get a code scanner and check the codes and post them up. AZ will check them for free.

Yes I agree, an oil pressure switch from them lasted a year before it went bad, but I got a new one for free under warranty so I'm cool with it, and the cps from them is working just fine as of now, but yes I need to get a better tps. And it isn't a wiring problem thankfully as it runs better unplugged/with this sensor than it did with the old one which shows the tps is able to send a signal, but what is odd is that there is literally no difference between the autozone sensor being plugged in and completely unplugging it, and both sensors I tried literally did nothing at all. Where can I get a quality tps? A dealer? Do other parts stores have better sensors?
 
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