99 4.0 automatic highway stalls

[Hopper]

My daughter is having issues with my old jeep that is know hers. Drives around town with no issues. Drives (65-70mph) on the hwy and stalls, sometimes. These are short hwy distances 10-15 min. Normally she will call me. I drive to were she's at, crank it up and drive it home and it seem fine. This only happens to her on the hwy. There are no codes, no check engine light, no signs.
Some issues I know of:
I had this issue 4 yrs ago with the stalling. Only difference is I couldn't restart the jeep for hrs after it would stall. Mechanic replaced Crankshaft position sensor (unknown brand probably NAPA), Fuel pump (Delphi). At that time 4yrs ago I was getting along start were I had to prime the pump by turning the key twice. Not sure which fixed the problem since they were both done at same time, but the stalling issue was solved. For some reason I did still need to prime the pump to start, but hey it didn't stall so I was good.
Today I was looking at the crankshaft position sensor and noticed the corrugated wire surround is melted from resting on the block. It doesn't appear the wires have melted but I need to inspect better.
Thoughts on were to start to figure this out?

 

[macleanflood]

My crankshaft position sensor failure on my 97 manifested as misfires...not random stalling.

I think you need to monitor live ODB data and possibly fuel pressure to figure out what's really going on.

-Mac

 

[jeepguy03]

The stalling was likely from the crankshaft sensor before, and probably is now if they used an aftermarket part. The extended crank time and need to prime the pump with the key is a common problem with the fuel pump check valve, which it sounds like they replaced and it didn't resolve that issue.

 

[Hopper]

The stalling was likely from the crankshaft sensor before, and probably is now if they used an aftermarket part. The extended crank time and need to prime the pump with the key is a common problem with the fuel pump check valve, which it sounds like they replaced and it didn't resolve that issue.

Yeah the Mopar sensors were impossible to find then, probably won't find one know.

 

[jeepguy03]

Yeah the Mopar sensors were impossible to find then, probably won't find one know.

Yeah the only Mopar one I see on Rockauto is for the manual transmission. If it were mine I'd try the NTK sensor, I've had good luck with their other sensors.

 

[hear]

My crankshaft position sensor failure on my 97 manifested as misfires...not random stalling.

I think you need to monitor live ODB data and possibly fuel pressure to figure out what's really going on.

-Mac

My 97 crank position sensor issue presented as random stalling. ¯\_(ツ)_/¯

 

[Hopper]

Thanks everyone Im gonna start with the sensor since the wires look a little burnt and it's cheap and easy to install. The little devil on my shoulder is telling me if I play my cards right this may scare my daughter away from the TJ and it could end up back in my parking spot

 

[John Cooper]

Thanks everyone Im gonna start with the sensor since the wires look a little burnt and it's cheap and easy to install. The little devil on my shoulder is telling me if I play my cards right this may scare my daughter away from the TJ and it could end up back in my parking spot

So then you could go wheeling with us sometime too???

Asking for the North Georgia bunch

 

[jeepguy03]

My 97 crank position sensor issue presented as random stalling. ¯\_(ツ)_/¯

Before I was even old enough to drive, I was familiar with the Jeep 4.0 crankshaft sensor. My father had a 1987 Cherokee 4.0 when I was a kid. It kept stalling at stop lights and randomly while driving. Occasionally would be a complete PITA to re-start if he stopped somewhere. This was ~1996 or so, and the problem wasn't super well-known by then. Not to mention 1987 Cherokees had the Renix electronic controls, no OBD2, so you had to be good with a volt meter and these sensors usually failed when hot. He had multiple shops throwing fuel pumps, ignition coils, distributors, you name it at the problem before one shop finally figured out it was the sensor and it ran perfect for another 10 years until someone hit him and totaled it.