93 Cherokee hard to start, stalls on the highway

Been a member here for a while, but have been lucky enough to not need to post any questions. I'll try to be thorough with my issue, please forgive me and point it out if I miss any important details.

I have a 93 Cherokee 4.0L (150k miles or so) that's gotten cranky lately. I don't drive it a lot, 3-10 times a month. And occasionally it will give me a hard time starting up. Just making a clicking sound initially when I turn the key, then slowly starting to turn over, this usually takes about 1-3 minutes to get going when this happens. Then it is usually fine.

This happened yesterday, since it's happened before I did not think much of it.
I was VERY low on fuel, so I filled the tank. Then drove for about 60 minutes in stop and go Seattle traffic on a hot day (no AC, good times). I was crossing a bridge doing about 60 MPH when the Jeep died, the radio and lights stayed on, but the car was stalled. No indicator lights, no symptoms leading up to it. Fluid levels all fine. Radiator is about 18 months old.

I sat on the bridge for about 10 minutes, then got it going again and was able to get off the freeway. It gave me the same cranky startup as it had earlier. It stalled 2 more times en route to my destination.

Once I got to where I was going. I checked for a diag code. I got "12" and "13".
"12" appears to be the memory clearing, and "13" has to do with the MAP sensor.

I found a few posts online discussing similar issues. The fixes ranged from fuel filters to bad spark plug connections resolved with contact cleaner or WD40. My regular mechanic who I trust suggested it could be the crank sensor, and I found a post here covering a similar issue where the crank sensor appeared to be the culprit.

It does seem like I may have 2 separate issues.

I am not a mechanic, I am a computer and audio tech by trade, but I am up for trying things myself, within reason. If it is the crank sensor, that is something I'd prefer to have my regular mechanic do. But, if it's worth trying some other things before taking it in, I'm up for it. I've got the Chilton manual, and can get my hands on some basic tools. But I'll be quick to admit when I'm in over my head, I certainly don't want to make things worse...

Sorry for the long winded post. Any suggestions appreciated. Even if it's "You sound like a noobie and it's over your head. Take it to the shop!"

After it dies and u turn the key to start it back up do u hear the fuel pump come on? If so then it's not the pump. I would start cheapest part and work your way up. Replace the coil, plugs, wires, cap and rotor. Don't be afraid to jump head first into your jeep. They are easy to work on and the more you work on it the more you will learn.

Thanks for the reply Twisted.
I can't recall if I could hear the fuel pump.. I was a little panicked sitting on the bridge as traffic piled up behind me, and not in the most observant state. Is the fuel pump the sound that is similar to washing fluid being pumped? Kind of a hum sound?

You are right, I really need to dive in and start poking around. I don't think I own an electronic device that I have not disassembled, but cars intimidate me for some reason. The Jeep does seem like a good car to learn on though, a lot of room under the hood..

If it is the cps, sometimes you can get away with just pulling it, cleaning the dirt/grime/grease off, and press on. I got a great running parts jeep for $100.00 that way. I ended up using that cps on my rig when my cps died. My jeep was doing the same thing when I got back from overseas the first time. Teach me to let it sit for weeks/months at a time.

It's a good idea to just go through it. Cherokees are reliable, and are hard to kill, but they aren't getting any younger

Don't start P/ing into the wind.

First, find out what is wrong with electrical system. Leaving your XJ sit a long time and the battery will discharge, so consider a trickle charger to keep it up. If you can't leave a cord stretched out then get a solar charger.

Put an overnight, better 24 hour, charge on the battery and have it load tested. This would be the right time to clean the cable ends and renew your grounds. If the battery, once fully charged, passes a load test, then see if the poor cranking persists or has been "cured".

If the low cranking has been cured, then drive it too see if the other problem still exists. What happened to you on the bridge could simply be battery/cable related.

jwolford said:

Thanks for the reply Twisted.
I can't recall if I could hear the fuel pump.. I was a little panicked sitting on the bridge as traffic piled up behind me, and not in the most observant state. Is the fuel pump the sound that is similar to washing fluid being pumped? Kind of a hum sound?

Click to expand...

yes thats the sound

Thanks guys. My impression was that getting to the CPS was not a straightforward procedure. I'll take a closer look at the manual, but I suspect that getting to that is a little beyond me.

Joe, a charger is a good connections. The "low cranking" only happens when it sits for a while, so it won't be easy to check. And wouldn't the fact that the radio, lights etc stayed active when the Jeep died indicate that it's not a battery issue?

I have a feeling that anything more than changing a filter or contact cleaner spark plug contacts will mean a trip to the shop. But I'm up for trying some stuff to avoid shoptime.

Twisted, thanks for the tip. I'll listen for the pump next time I have trouble starting.

You can have enough voltage for the lights, etc, but when the supply drops under 9 volts the sensors and ecu/pcm won't funtion correctly, if at all.

The slow crank could just be from sitting, or the sign of a failing battery or cables. Either way, those would be screwing with your voltage.

Gotcha. Thanks Joe.

i actually had the slo cranking problem and it was definantly the starter, once i changed that it starts like a champ! so check the starter betcha its that! and the diagnose 13 code i would suggest gettin a new or used map sensor, unfortunately for me no junk yards around here have the newer map sensor ao i had to buy a new one from napa auto for $130 but for a 93 they are only $39 for the cheapy and $72 for the spendy one

Thanks for the tip 4.0.

I just dropped it off at the shop. Considering the variables, and my lack of experience, letting the shop handle it seemed the best route. But this thread has inspired me to get to know my Jeep better and start "attempting" my own repairs and maintenance. I'll start with simple stuff and work my way up. I just need to retrain my brain to see it as "modular" as opposed to one big machine I do not understand. I am fine working on other machines, no reason I can't do this. I suppose it's a mental block that I've carried over from my teens... Heheh....

Thanks again for all the good advice and encouragement. I'll report back when I find out what the culprit is.

So I got the Jeep back on Wednesday and just wanted to report the findings.

Unfortunately, the shop never saw either problem, but with my authorization, they did a few repairs that they thought would be the most likely culprits.

For the starting issue, they suspected the neutral safety switch, this was cleaned and repaird.

For the stalling issue, as you guys had suggested, they suspected the crankshaft position sensor. So that's been replaced.

So far so good. The stalling only happened the one time, but that one time sucked pretty hard. And the starting issue was cropping up once a month, so it will be easy to tell if that's fixed.

They also found an issue with the water pump leaking, but that would cost more than I have to fix it. I am opting to limp along with it, checking the levels every few days to be sure I am not running it dry.

Thanks again for the advice...

Just thought I'd check back in. I've been driving the jeep more frequently recently 6-7 days a week, short distances.

A couple of days ago It gave me a little trouble getting going, slow to turn over, but then it was OK. This morning, even slower, it painfully cranked a few times, then clicking only when the ignition was in the "start" position. I could not hear the fuel pump going. There was enough power to turn on the radio or the lights. I did not have the patience to "finesse" it into starting, so I just took another vehicle.

I'll call the shop on Monday, but they did not see the problem before, and found nothing wrong with it. It will probably work fine later today. So I don't know what the hell to do.

I have not charged or tested the battery myself, but I believe it was tested in the shop. I have a volt meter, a few BASIC tools and the Chilton manual. beyond that, I'll either need to take it in or buy some tools. Any SIMPLE things I can try would be great. I don't have a lot of tools, experience or space, but I am up for doing things myself when possible.

I'll reread the thread for advice, but thought I'd bump this in case there were any other suggestions for the starting issue.

Could not find anything in the manual on testing the battery voltage, but since it is just a big damn battery with a "+" and a "-" I tested it with the volt meter, and it read 11.3v. I believe it's supposed to be 12v so I suspect that is within spec. It did grudgingly start for me just now.

The terminals look a pretty dirty, but could that actually be the problem?

Got a diag code of "24" which is "Throttle position sensor voltage high or low".
Researching that now

It may or may not be worth noting that I had less than 1/4 in the gas tank both times this happened this week.

yeah the dirty terminals can cause strange things, also my '94 has some ground wires that connect to the engine on the back side close to the furthest spark plug wire on towards the back of the motor. once when i was doing some work on my jeep i disconnected those grounds and it wouldn't start, the starter turned SLOWLY and sounded horrible. with yours being slow to turn over, and you being an electrical nerd, i suggest looking for any frayed wires/grounds!

and throw a couple more gallons of good gas in it just for good luck

$700later said:

and throw a couple more gallons of good gas in it just for good luck

Click to expand...

Good call. I am noticing a trend here with stalling/staring issue and low fuel.
Could it be a sensor reading incorrectly because of low fuel?

"Electrical Nerd"? Ouch! Meh... It's true.
Voltage scares me far less than a combustion engine.

I eyeballed all the connections I could see, and just sort of wiggled all the plug connections I could get to easily. I am still not entirely clear on what I am looking at under the hood. But I am getting more comfortable and the Chilton manual is helpful (as are kind folks like yourself in this forum!).

I am reading through this thread:
http://www.naxja.org/forum/showthread.php?t=980830&highlight=throttle+position,+code
which refers to an error code 24 and the TPS.

Remove both battery cables and clean with baking soda and water or a batt terminal cleaner form parts store and a wire brush. Get them clean/shiny. Trace both cables, remove and clean all conections. Look around engine and remove/clean any and all ground conections. Sand paper works well. Make all conections clean and shiny.

Next, remove battery and take it to your favorite parts store and have them do a 24 hr trickle charge. The next day return to store and have them do a load test on your battery. If it passes, reinstall battery and see how it starts. If it fails, buy the best battery you can afford, no cheap bateries.

All this is basiclly free other then the terminal cleaner, and will give you a good foundation to test other electrical components. Also will get you comfortable under the hood.

Thanks for the good advice Plymatt.
I just cleaned the cables and terminal connections with baking soda and water.
Gave it about 10 minutes, scrubbed and wiped it all down, now it's just clicking when I turn the key...

Voltage now reads closer to 10.5/11v.

My neighbor is gonna give me a jump here in a bit.

I tried to find the TPS to test it, but could not for the life of me locate it under the hood. The manual refers to it being on the throttle plate assembly, which I could not find either.