jeep not cranking... sometimes

wranglerrambler

Well-Known Member
Joined
Dec 28, 2006
Location
oxford,nc
Well I have a problem.

When my jeep gets warm/hot and i turn it off it won't recrank. Unless you let it cool down, or are able to get it rolling and dump the clutch. I have a 97 TJ with a 4.0 in it. The check engine light came on and it threw a camshaft position sensor problem, but from reading in a chilton type manual only 2000's have that part. should i go ahead and replace the distributor or what? I checked the plugs and wires and all seems good, but havent checked to see if it is actually getting spark. The jeep turns over but just doesnt sound like its getting spark.......
 
when the engine is warm and you cut it off if your residual fuel pressure drops instantly in the injectors and fuel rail then it will vaporize. Put a fuel pressure gauge on the fuel rail and check it to whatever the spec is. If it is below spec then you likely have a fuel pressure regulator or pump issue.

I would also double verify the code.
 
97 TJs have a CPS on them. side of the bellhousing

awww.4x4xplor.com_images_cps_DSC02130.jpg


Could be your issue, Its common to cause cranking issues
 
change the cps. It will only get worse.
 
The crankshaft position sensor is a common problem on TJ's. The camshaft position sensor was introduced on 2000 model year TJ's and is a unit that replaces the distributor and works in conjuction with the coil over plug ignition system. While it is a more robust system in my opinion, it does still have problems. I had poor cranking and intermittent power delivery problems on my 2000 around 55k miles, and had to replace the cam position sensor.
 
I've replaced both sensors on my tj. It will only get worse. When electronics go bad they do not like heat.
 
jeepinmatt said:
The crankshaft position sensor is a common problem on TJ's. The camshaft position sensor was introduced on 2000 model year TJ's and is a unit that replaces the distributor and works in conjuction with the coil over plug ignition system. While it is a more robust system in my opinion, it does still have problems. I had poor cranking and intermittent power delivery problems on my 2000 around 55k miles, and had to replace the cam position sensor.
Click to expand...

I stand corrected.

So two different sensors, Cramshaft and Crankshaft?

Thanks
 
burrellsjeep said:
I stand corrected.

So two different sensors, Cramshaft and Crankshaft?

Thanks
Click to expand...
Yep, but only on 2000 and newer 4.0's. The 97-99 still have a standard distributor and crank position sensor.
 
jeepinmatt said:
Yep, but only on 2000 and newer 4.0's. The 97-99 still have a standard distributor and crank position sensor.
Click to expand...

Crank position sensor could still be the no starting issue on the 97 correct?

Just wanna be sure I understand, I have a 97 that my FIL has that won't crank and need to work on it when the weather gets better (spring) and this was one of the first things I was going to check.
 
burrellsjeep said:
Crank position sensor could still be the no starting issue on the 97 correct?

Just wanna be sure I understand, I have a 97 that my FIL has that won't crank and need to work on it when the weather gets better (spring) and this was one of the first things I was going to check.
Click to expand...
Yes, could very well be crank position sensor on a 97. If it will crank under throttle, but not without, could be the IAC (Idle Air Control). Its a module on the throttle body, along with the TPS (throttle position sensor). They all cause problems, but the crankshaft is the most common.
 
been busy so i hadnt been able to get back on

John, youre right. but its small things like this that help prevent me from the trails.

When it won't crank it doesnt matter if i give it throttle or not... just making that comment based on what someone said about the IAC. A buddy said it may be the coil...

who knows. Gonna check on different things this week and will let you know what I find out. Thanks everyone.
 
well i finally did the fuel pressure test...

Here's what the results were... With the jeep running the pressure was about 49, when I turned it off (with the ignition turned on, but not running) the pressure slowly dropped to about 21psi but went back up to about 24psi... So does this sound like the fuel pump still needs to be replaced? Seems to have good fuel pressure.
 
CPS will fix it.
 
You most certainly have a camshaft position sensor. It is under the distributor cap. It's a flast, round plate that has a 2 wire connector coming off of it.

A failed crank position sensor *can* trip a cam position sensor dtc. I typically suggest to replace them both if one requires replacement.

When you say it wont re-crank, does it spin over and not start, or not crank over at all?

I'll help ya out best I can...
 
CPS is a nightmare for all jeeps... end of story.
 
when i say it won't recrank.... It turns over like a charm but doesn't seem to fire. Sometimes it works great with no issues then other times... good luck.

I read and figured out about the camshaft sensor. Its called a stator and is the pick up in the distributor. thanks for your help.
 
well well well............ back in march when I started this thread, I ended up replacing distributor (which is where the stator/ camshaft position sensor is, the crankshaft position sensor, water temp sensor, and eventually the problem stopped occuring. well its back. sat for an hour and a half and still wouldnt crank. trailered it home and unplugged the crank sensor, turn the ignition on, plugged sensor back in, then it fired right up. what the hell. called auto zone and they will have my replacement Crank sensor in tomorrow... (luckily there's a two year warranty.)

I wouldnt have thought it would have gone out since march.:confused:
 
This is one of the sensors (along with, say, O2 sensors) where the genereal concensus seems to be "stick with mopar". fwiw.
 
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