Codywitkowski_28

Ive has issues while driving down the road with my xj dying everything electrical would stay on but the engine would die. After a few min it would restart and run fine until dying again. Recently it has progressively gotten worse. Ive replaced the distribuitor CPS TPS and wires. Im at a loss.

cruiser54

Ever clean your throttle body and IAC?

Courtesy of TJWalker:

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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

"Gently" wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Codywitkowski_28

Not to long ago.

Codywitkowski_28

its like i lose spark. it will die and ill have to wait a good 5 minuets now to restart it as its being reluctant.

randall L

Having these problems when it's at operating temp or cold? Or both?

Codywitkowski_28

At temp.

randall L

I dealt with similar issues for months. Even after I replaced lots of stuff. The CPS SHOULD be a MOPAR & INSTALLED PER CRUISERS tips section.

If you are having op temp problems you may want to look at this.

MPI Fuel Pressure Leak Down Test with Engine Off

If abnormally long periods of cranking are required to restart a hot engine after the vehicle has been shut down for a short period of time, fuel pressure may be bleeding past the fuel pressure regulator or the check valve in the outlet end of the fuel pump.

1. With the engine off, connect an accurate 0-689 kPa (0-100 psi) fuel gauge to the pressure test port fitting on the fuel rail.
2. Start the vehicle and let engine idle. Check fuel pressure reading on gauge. Fuel pressure should be within specifications. Refer to MPI System Fuel Pressure Test.
3. Shut engine off. Note fuel pressure reading on gauge. Leave fuel pressure gauge connected. Allow engine to set for 30 minutes and then compare fuel pressure reading on gauge to reading taken when engine was shut down. A pressure drop up to 138 kPa (20 psi) to a range of 131-269 kPa (19-39 psi) is within specifications.
4. If fuel pressure drop is within specifications, the fuel pump outlet check valve and the fuel pressure regulator are both operating normally.
5. If fuel pressure drop is greater than 138 kPa (20 psi), restart the vehicle and let engine idle. CAUTION: Fuel pressure will rise to as much as 95 psi when the fuel return line is pinched shut, shut engine down immediately after pinching off fuel return line.
6. Momentarily pinch shut the hose section of the fuel return line and shut engine off. Note pressure reading on gauge. Allow engine to set for 30 minutes. Compare fuel pressure reading to reading taken when engine was shut down. If fuel pressure drops approximately 138 kPa (20 psi), replace the fuel pressure regulator. If fuel pressure has dropped considerably more than 138 kPa (20 psi) fuel pressure is bleeding off past the outlet check valve in pump and the fuel pump must be replaced.

Codywitkowski_28

I will try that, but its speradic. It will crank for long periods of time after it dies, yet if i shut it off while at temp it will restart without a problem.

randall L

My 89 would run fine. Shut it off at op. temp. it would re start right away. If I waited 5 minutes it would not start again until it cooled off.(some)
Turned out to be the check valve was bad. I put a new BOSCH fuel pump in & haven't had the problem since.
This was after replacing just about everything else. Which I was doing a restoration anyway but none of the new parts fixed the stall, non start until I replaced the pump.
The above test is what finally pointed me to the pump. My fuel pressure was bleeding off way to soon. Leaking past the check valve.

Codywitkowski_28

Well I did the pressure test over the last weekend and everything is within spec. I pulled the tank and inspected all the wires and found a corroded ground to the fuel pump. I replaced the ground and reinstalled the tank and I'm still having the same issue of it speradically dying on me. I'm thinking it could be the computer. Anymore suggestions?

Agent_Oragnge

check out the relay diagram that Cruiser posted yesterday. not a bad idea to pull the relays and wire brush them till nice n shiny. clean up the receipticles too.
https://www.cherokeeforum.com/f2/sta...stalls-166505/

Codywitkowski_28

I might just be brain dead at the moment but what relays are you talking about?

Codywitkowski_28

Never mind i was on my phone at the time, just logged in on my computer and was able to see the link. Ill refresh all the conections again and get back to you. Thanks.

cruiser54

ECU is the LAST place to look.

Clean and refreshh ALL engine bay connectors.

TEST your CPS. Make sure your intake manifold bolts aren't loose. Inspect for vacuum leaks.

Refresh your grounds.

Click on the "pink link" in my signature and do #1, #3, and #7.

Codywitkowski_28

I did everything youve suggested and it didnt die on me for a few days. Today I jumped in it started it and about a half mine down the road she died again. I waited about 5 minutes and she reluciently started.