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4.0 l engine not running

P

pszczepan

NAXJA Forum User
Location
IN
Hi !

I have Jeep Chrokee 1989 wiyh 4.0 l. I have also service manual and till now I checked couple things:
- fuel is delivered to fuel rail
- I have spark on Spark plugs
- I looked into the spark plug whole during the cranking and I noticed that so much fuel is going to the chamber. I think that fuel has enough power to put out the spark from plug and thats why the engine cannot start.

Could you write me which sensor is the most important for injector pulse width - maybe the sensor does not work and ECU gives to long pulse width and thats why the sparks are wet.

Thanks for any advie
Pawel
 
How could be timing off if everything was OK, worked perfect and now nothing - but the spark is. I will check sparks and pressure regulator
 
I am having the EXACT same problem buddy.

-new plugs
-timing setup according to the manual (lining up the timing marks on the bottom wheel will tell you exactly where top dead centre is for cylinder one and thus, where you spark plug wires go on the dizzy)
-new cps
-new MAT sensor
-new coolant temp. sensor

EDIT: This thing started a month ago a couple days after it savagely overheated, what could have caused it to stop working since then?

Even with all this the engine doesn't even bite when I try to start it, it just cranks.

If you figure this out PLEASE let me know.
 
does it crank faster than normal. Hows the coil?
 
Since the problem happened right after overheating, the best way is to focus on what could have changed in the overheating. This means the engine and things closely attached, like on the manifold or bellhousing.

It's important that you verify you have spark. If so, then the CPS, ground connection, and other sensors are OK. Even if something was reading way out, it would still start if it didn't run well.

Excess fuel could be a problem, and the injectors can be senstive to overheating. Turn the ignition to run, then disconnect a wire on the fuel pump relay. Then crank. If it's flooding, it should fire or kick a bit as you crank and the cylinders clear. It won't run long, but if it starts to try, vs nothing, it's flooded. Reconnect and try. That will narrow it to fuel feed.

It can run with the pressure regulator disconnected just fine. However, if the diaphragm broke, you will see gas in the vacuum line. Check that too. It's on the fringe of the heat zone, but the previous test will work for this too. Of course, just checking the vacuum line will tell.

If no spark, it could be a whole other mess. CPS doesn't directly manage injector width, so it won't flood from that. If no spark, check the block and body grounds (notoriously bad), unplug and replug the CPS (the connector is flakey - with ox guard on it you never have to do that again, showing it isn't a'reset' problem but a corrosion problem), it'll run without a temp sensor, but could be a TPS too.

Try these and let us know.

Skip
 
skipc said:
Since the problem happened right after overheating, the best way is to focus on what could have changed in the overheating. This means the engine and things closely attached, like on the manifold or bellhousing.

It's important that you verify you have spark. If so, then the CPS, ground connection, and other sensors are OK. Even if something was reading way out, it would still start if it didn't run well.

Excess fuel could be a problem, and the injectors can be senstive to overheating. Turn the ignition to run, then disconnect a wire on the fuel pump relay. Then crank. If it's flooding, it should fire or kick a bit as you crank and the cylinders clear. It won't run long, but if it starts to try, vs nothing, it's flooded. Reconnect and try. That will narrow it to fuel feed.

It can run with the pressure regulator disconnected just fine. However, if the diaphragm broke, you will see gas in the vacuum line. Check that too. It's on the fringe of the heat zone, but the previous test will work for this too. Of course, just checking the vacuum line will tell.

If no spark, it could be a whole other mess. CPS doesn't directly manage injector width, so it won't flood from that. If no spark, check the block and body grounds (notoriously bad), unplug and replug the CPS (the connector is flakey - with ox guard on it you never have to do that again, showing it isn't a'reset' problem but a corrosion problem), it'll run without a temp sensor, but could be a TPS too.

Try these and let us know.

Skip
Click to expand...

The 89 Renix will flood just from 60 seconds of cranking with out it starting. If you press the gas peddle to wide open throttle (floor it and hold it there while cranking) on the Renix Jeeps the ECU shuts off the injectors allowing the engine to dry out and finally start. Once it turns over and trys to start let off the gas.

Then , if it does not start doing that you have a timing, harware or electrical (spark) problem.
 
There is a troubleshoot thread in the FAQ forum that is all about this issue.
 
The 89 Renix will flood just from 60 seconds of cranking with out it starting. If you press the gas peddle to wide open throttle (floor it and hold it there while cranking) on the Renix Jeeps the ECU shuts off the injectors allowing the engine to dry out and finally start. Once it turns over and trys to start let off the gas.
Click to expand...

Except if there's a problem or misadjustment with the TPS... If you want to be sure, do it the manual way, although pedal to the floor, while vacuum line open, is even better.

Skip
 
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