jeepyrex

After reading quite a few posts here on the forum trying to trace down what's wrong with my Jeep I thought I might as well join...

Well here's the issue:
1990 2WD 4.0 6cyl miles: 125000 starts up on the 3rd crank when cold.
It runs for a while and then dies.

After it dies there is No spark and hardly any gas pressure.
The next day it will start and do the same thing.

history:
Problem got gradually worse with hard warm start earlier this year and
then die offs after 15 miles gradually getting shorter now it might die anytime.

Parts replaced:
cap, cables, plugs, airfilter, gas pumps ( 2nd within 800 miles although I think it has nothing to do with the problem), gas filter, CPS, starter, battery,
seafoamed throttle, MAP sensor vacuum hose checked.
jumped the ballast resistor ( which get's quite hot ).


If anybody here has an idea what's wrong with my rig
I'd be most grateful.

jeepyrex

Diesel

Cam Shaft position sensor, TPS.

jeepyrex

Thanks Diesel,
How could I test for that ?

Diesel

TPS-Take a DMM and test the three wires. There should be 3 wires, one ground usually black. A 5v reference wire which should read somewhere around 5v and then a signal wire which with the throttle shut should read around .5 and at WOT read around 4.5. With the DMM read the signal wire voltage as you manually open the throttle to WOT it should be a smooth transition not jumpy from .5 volts to 4.5 volts.

Stator test- http://www.lunghd.com/Tech_Articles/...lse_Stator.htm

jeepyrex

I guess I check the TPS first - makes more sense YES/NO ?

Meanwhile many thanks !

bradp111

Hi there I just joined so I could post a question about a problem I'm currently having with my 89 Cherokee but the problem you're having sounds pretty similar to one I had when I first bought my Jeep 6 months ago. I had no trouble starting at all then I would drive it a while and it would start running rough and died a few times or I would drive down the road to a store turn it off and then it didn't want to start. I checked/changed fuel filter, plugs, cap/rotar, wires and other stuff with no luck. One way to know its a bad sensor is to disconnect the negative for a minute to trick/reset the computer then try to start it again I did it several times when I was stuck somewhere and it worked. I would have problems more often when it was really warm outside or after I had been driving around for a while but the problems got to be more and more frequent.Anyways I did a lot of reading which is frustrating that lots of problems have similar symptoms but I took a chance and bought a Coolant Temperature Sensor which was $25.99 at NAPA. After replacing that sensor it ran fine. Although I don't think its anything to do with your problem I should tell you that I changed the CPS(crank position sensor) a few months later because of problems starting. Without a diagnostic tool the only way to check sensors is by a voltage test. I figured I might as well try it because I didn't have a voltage tester to use and NAPA had the coolant sensor so I tried it and it worked. This might not make sense to you it didn't make any to me either why a coolant temp sensor would cause it to do that but it tells the computer what air/fuel mix to send based on the temp so when its bad it can cause it to run rough. Hope this helps I'm no mechanic but I hope to help because I know how aggravating it is trying to figure out the problem sometimes...

jeepyrex

Thank you for the info.
I understand your line of thinking with the cooling sensor.
But the car does not even get to temperature an shuts off now.
I checked fuel pressure again and it has plenty.
Oh well... Just empty every pocket - I guess.