90XJ randomly stalling

Zoro · Jan 11, 2006

It just started to do this yesterday, I would put it in neutral to freewheel and the motor would just die, happened maybe 6 or 7 times on a 25 mile drive so this morning I run it really low on gas and manage to get to the pump as it starts to sputter so I put 10 gallons in and that seemed to have taken care of the problem.

So today on my way home I'm sitting at a red-light and it stalls, I had it in neutral with my foot on the brake and off the clutch and off the gas, so I start it back up and 2 minutes later it wants to do the same thing but I gave it some gas and it was fine.

Could this be bad gas or a TPS problem? It's a 90XJ, 4.0, AX-15 and aout 190K miles.

I don't know if it's a related issue or not but recently it's been hesitating alot in the mornings the first few times I put it in gear...

Sorry for the long post and thanks in advance for the help.

serge · Jan 13, 2006

Zoro said:
Could this be bad gas or a TPS problem? It's a 90XJ, 4.0, AX-15 and aout 190K miles.

Did you check the fuel pressure? How long ago did you replace the fuel filter?

TPS sensor is easily checked with a DMM. Search for that ...

4xBob · Jan 13, 2006

When the TPS was going out, I had a high idle on my 1990 4.0--not a low idle or ocassional stall. What you describe is exactly what happened when the CPS went- it would die at idle or just as the gas pedal was touched. The result of no CPS signal is the computer shuts off spark and fuel injectors. Try disconnecting the plug located at the rear, driver's side of the head, clean the contacts, and replug. This may get you home or get a little more time out of it. The CPS is on the bell housing, near top, driver's side. If you are in exactly the right place, you can reach it from below if your arm isn't too big. If you need to replace it, get the high altitude CPS from the dealer, available only for Renix (up to 1990) 4.0 engines, to advance the timing a bit for slightly more power. You can also buy the CPS in a kit with a small harness to connect it directly to the ECU (computer). This is a good idea- I had difficulties getting good connection through the jeep harness on my daughter's 4.0

Zoro · Jan 13, 2006

So about how much is the CPS to replace with the high-altitude version?

wilcharl · Jan 13, 2006

CHECK YOUR GROUNDS esp the one from the back of the engine by the rear of the manifold to the firewall that did it for me... random stalling fixed

Zoro · Jan 20, 2006

Fixed it today, ever since I got mine the plug for the MAP sensor vacuum tube on the throttle body has been coming un-done and falling out so today as I reset it it breaks right at the bracket, $3 buck later and some JBweld it's fixed, the thing will never come out again and random stalling and hesitation fixed.

Zoro · Jan 20, 2006

4xBob said:
When the TPS was going out, I had a high idle on my 1990 4.0--not a low idle or ocassional stall. What you describe is exactly what happened when the CPS went- it would die at idle or just as the gas pedal was touched. The result of no CPS signal is the computer shuts off spark and fuel injectors. Try disconnecting the plug located at the rear, driver's side of the head, clean the contacts, and replug. This may get you home or get a little more time out of it. The CPS is on the bell housing, near top, driver's side. If you are in exactly the right place, you can reach it from below if your arm isn't too big. If you need to replace it, get the high altitude CPS from the dealer, available only for Renix (up to 1990) 4.0 engines, to advance the timing a bit for slightly more power. You can also buy the CPS in a kit with a small harness to connect it directly to the ECU (computer). This is a good idea- I had difficulties getting good connection through the jeep harness on my daughter's 4.0

So how much will the high-altitude CPS or the CPS kit set me back?

90XJ randomly stalling

Zoro

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serge

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4xBob

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Zoro

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wilcharl

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Zoro

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Zoro

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