'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Yes a CPS can cause those problems..or it can cause total ignition failure (no start at all). My CPS failed and it would start the XJ, run normal for weeks then just die (not fun on the highway) worst of all it didn't throw any codes for the stealership to read. It was changed out on spec. and solved the problem. Has your "trusted mechanic" read the codes stored in the 'puter? If not start there, if he has then you might want to change the CPS anyways.

Snow...
"bowgus" <Bowgus@rogers.com> wrote in message news:mVukb.196662$ko%.99978@news04.bloor.is.net.ca ble.rogers.com...
'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Yes a CPS can cause those problems..or it can cause total ignition failure (no start at all). My CPS failed and it would start the XJ, run normal for weeks then just die (not fun on the highway) worst of all it didn't throw any codes for the stealership to read. It was changed out on spec. and solved the problem. Has your "trusted mechanic" read the codes stored in the 'puter? If not start there, if he has then you might want to change the CPS anyways.

Snow...
"bowgus" <Bowgus@rogers.com> wrote in message news:mVukb.196662$ko%.99978@news04.bloor.is.net.ca ble.rogers.com...
'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Yes a CPS can cause those problems..or it can cause total ignition failure (no start at all). My CPS failed and it would start the XJ, run normal for weeks then just die (not fun on the highway) worst of all it didn't throw any codes for the stealership to read. It was changed out on spec. and solved the problem. Has your "trusted mechanic" read the codes stored in the 'puter? If not start there, if he has then you might want to change the CPS anyways.

Snow...
"bowgus" <Bowgus@rogers.com> wrote in message news:mVukb.196662$ko%.99978@news04.bloor.is.net.ca ble.rogers.com...
'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Thanks Snow ... that's what I was hoping to hear. I was just out cranking it over, poking around, looking up at that CPS thinking if I get it out, I'll still have to bus it out to the dealer on monday etc etc ... and miss a day at work. So monday I'll have my trusted mechanic replace that CPS which seems to have now failed completely ... nothing worse than intermittents. About the mechanic ... he's in my opinion high on ability, integrity and honesty ... and has been excellent for past work that I thought better suited to a mechanic than to me. About the codes .. no codes stored ... which makes sense to me, since it never failed while running. Anyway, the battery charger's on ... and that's that. Thanks again buddy!
"Snow" <snowball_2004@msn.com> wrote in message news:2txkb.90$XO.43933@news20.bellglobal.com...
Yes a CPS can cause those problems..or it can cause total ignition failure (no start at all). My CPS failed and it would start the XJ, run normal for weeks then just die (not fun on the highway) worst of all it didn't throw any codes for the stealership to read. It was changed out on spec. and solved the problem. Has your "trusted mechanic" read the codes stored in the 'puter? If not start there, if he has then you might want to change the CPS anyways.

Snow...
"bowgus" <Bowgus@rogers.com> wrote in message news:mVukb.196662$ko%.99978@news04.bloor.is.net.ca ble.rogers.com...
'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Thanks Snow ... that's what I was hoping to hear. I was just out cranking it over, poking around, looking up at that CPS thinking if I get it out, I'll still have to bus it out to the dealer on monday etc etc ... and miss a day at work. So monday I'll have my trusted mechanic replace that CPS which seems to have now failed completely ... nothing worse than intermittents. About the mechanic ... he's in my opinion high on ability, integrity and honesty ... and has been excellent for past work that I thought better suited to a mechanic than to me. About the codes .. no codes stored ... which makes sense to me, since it never failed while running. Anyway, the battery charger's on ... and that's that. Thanks again buddy!
"Snow" <snowball_2004@msn.com> wrote in message news:2txkb.90$XO.43933@news20.bellglobal.com...
Yes a CPS can cause those problems..or it can cause total ignition failure (no start at all). My CPS failed and it would start the XJ, run normal for weeks then just die (not fun on the highway) worst of all it didn't throw any codes for the stealership to read. It was changed out on spec. and solved the problem. Has your "trusted mechanic" read the codes stored in the 'puter? If not start there, if he has then you might want to change the CPS anyways.

Snow...
"bowgus" <Bowgus@rogers.com> wrote in message news:mVukb.196662$ko%.99978@news04.bloor.is.net.ca ble.rogers.com...
'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Thanks Snow ... that's what I was hoping to hear. I was just out cranking it over, poking around, looking up at that CPS thinking if I get it out, I'll still have to bus it out to the dealer on monday etc etc ... and miss a day at work. So monday I'll have my trusted mechanic replace that CPS which seems to have now failed completely ... nothing worse than intermittents. About the mechanic ... he's in my opinion high on ability, integrity and honesty ... and has been excellent for past work that I thought better suited to a mechanic than to me. About the codes .. no codes stored ... which makes sense to me, since it never failed while running. Anyway, the battery charger's on ... and that's that. Thanks again buddy!
"Snow" <snowball_2004@msn.com> wrote in message news:2txkb.90$XO.43933@news20.bellglobal.com...
Yes a CPS can cause those problems..or it can cause total ignition failure (no start at all). My CPS failed and it would start the XJ, run normal for weeks then just die (not fun on the highway) worst of all it didn't throw any codes for the stealership to read. It was changed out on spec. and solved the problem. Has your "trusted mechanic" read the codes stored in the 'puter? If not start there, if he has then you might want to change the CPS anyways.

Snow...
"bowgus" <Bowgus@rogers.com> wrote in message news:mVukb.196662$ko%.99978@news04.bloor.is.net.ca ble.rogers.com...
'96 XJ 4.0 litre ... starter turns, dashlights light, no check engine/trouble codes appearing ... but will not always fire up

1) Two weeks ago had the above starting problems ... and finally the jeep would not start at all so to my trusted mechanic who looked it over, then replaced the fuel pump/regulator and filter. Drove around for 2 weeks, no problems and the jeep is now starting first turn of the key .... the way I expect fuel injection to work.

2) Thursday night ... starter turns etc and maybe on the 8th try, the jeep starts up and runs perfectly normal.

3) Saturday morning for the heck of it, I disconnect the crankshaft position sensor (CPS) to see what the symptoms might be ... exactly as when the jeep won't start ... so I cleaned the connector pins as best I could, applied WD40 to it, and figured that was that. Drove around all day doing chores, no problems.

4) Saturday night jeep won't start ... it's dark, I go into the house, pour a double and watch a movie.

5) Sunday morning, questions.

Q1) Has anyone had a crankshaft position sensor (CPS) fail such that the jeep will sometimes start, sometimes not ,,, and run perfectly once started?
Q2) Could the problem be the camshaft position sensor (located on the oil pump)? Is it worth my while to clean that connector?
Q3) Is it worth my while to start checking/cleaning all connectors to the computer (PCM) that I can get at?

Or just take it back to my trusted mechanic for follow up on the fuel pump which I'll do later in the week anyway.

Thanks

 

Maybe try a booster cable from the battery negative to the firewall
first.

Had the same symptoms, changed CPS, no joy. The ground strap from the
head to the firewall was dead.

I don't know what kind of html you are using, but my PC won't quote it.
This is a text group and not everyone can even read html, so I post in
text.

My server even cuts lots of them out.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

 

Maybe try a booster cable from the battery negative to the firewall
first.

Had the same symptoms, changed CPS, no joy. The ground strap from the
head to the firewall was dead.

I don't know what kind of html you are using, but my PC won't quote it.
This is a text group and not everyone can even read html, so I post in
text.

My server even cuts lots of them out.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

 

Maybe try a booster cable from the battery negative to the firewall
first.

Had the same symptoms, changed CPS, no joy. The ground strap from the
head to the firewall was dead.

I don't know what kind of html you are using, but my PC won't quote it.
This is a text group and not everyone can even read html, so I post in
text.

My server even cuts lots of them out.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's