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Jeep Not Starting

Starboard M

NAXJA Member
NAXJA Member
Location
WA
Background: A couple weeks ago I went wheeling in some mud pits that I normally don’t go into. However, from the pressure from friends I went through. After this excursion, my Jeep ran fine. It did however kill the alternator, which I replaced.
Problem: But last week it wouldn’t start. The starter motor turns it over but it wont catch and fully start. I just put in the starter a couple weeks ago. At first I thought I might have gotten water into the intake because I had mud and oil on it (From a blown AT hose blow). Cleaned the K&N air filter and put it back on. Throttle body was clean. Then I tried disconnecting all the fittings and stuff that are in the engine bay. Also replaced the fuel filter and distributor cap. Then, yesterday, it started fine and ran until this morning. What is wrong? I’ve looked and found that it could be the CPS, MAP, or the IAC. Are there any tests that I can run on these to see if they are bad? Any other ideas? TIA

1989 XJ 4.0 with an automatic
 
Most of the time, a no-start where it cranks over but no go, is due to no fuel or a bad CPS...
Sometimes you can "quick-fix" a CPS by unplugging it, cleaning the connectors and replugging it. If it starts, then you probably need a new CPS.

For fuel probs, you gotta first check to smake sure the fuel pump is working. On my '88 when I turn the key to "on" I can hear it whirr for a few secs...

Fourtunately, most of my probs have been with the TPS and CPS... The TPS usually affects the performance of a running engine.
 
Gil BullyKatz said:
Most of the time, a no-start where it cranks over but no go, is due to no fuel or a bad CPS...
Sometimes you can "quick-fix" a CPS by unplugging it, cleaning the connectors and replugging it. If it starts, then you probably need a new CPS.

For fuel probs, you gotta first check to smake sure the fuel pump is working. On my '88 when I turn the key to "on" I can hear it whirr for a few secs...

Fourtunately, most of my probs have been with the TPS and CPS... The TPS usually affects the performance of a running engine.
When I turn it to the "on" position, I can hear the fuel pump. So I dont think its that. Where is the CPS located? There are so many thing on this engine so I dont know where that is.


edit: Found that the CPS is on the bellhousing at the 11 oclook position. From reading it sounds like if the CPS is bad it will start sometimes but die after a couple of miles. When it starts, once in a blue moon, it runs fine. So would you still sugest the CPS?
 
Last edited:
Let me see if I can get it right...

CPS is at rear of engine on the bellhousing right by the firewall, it's near the top at the 11 o'clock position if you're facing the engine.

The wires that connect to the CPS are a few inches long and the connector is usually towards the rear by the last injector...

Although this applies to ZJ's... it's still a Jeep 4.0 engine to give ya an idea

cps_4a.gif


There's a lot of info on CPS if search past posts...

they tend to be a common problem
 
Well tonight I tried to start it up. Didnt start. Tried using the on position, off, on position, off, on , start and it worked. I looked at the CPS and dang, thats going to be fun to replace if it needs to come off. What side do I take off if I just want to see if there is any stuff in the conection? I assume the part that attatches to the bellhousing.
 
Be careful when you are messing with the wires that lead into the cps.On mine the insulation was very brittle from the heat and one of the two wires broke off. Its a $40 or 50 dollar part at kragens.
 
Starboard M said:
Well tonight I tried to start it up. Didnt start. Tried using the on position, off, on position, off, on , start and it worked. I looked at the CPS and dang, thats going to be fun to replace if it needs to come off. What side do I take off if I just want to see if there is any stuff in the conection? I assume the part that attatches to the bellhousing.

I would check the connector. Its up top at the intake manifold which you can just see in the above photo. Most of the time it's a connection problem but the CPS gets replaced. Usually when the CPS goes out it will act up after the engine is hot.
 
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