no start...
05-01-2011, 04:37 PM
#1
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Year: 1989
Model: Cherokee
Engine: Renix 4.0L
no start...
So I parked my jeep for a few days, wentto start it today.
It would start and run for a couple seconds then die. Each time. Now it just wont start at all. Any ideas?
It would start and run for a couple seconds then die. Each time. Now it just wont start at all. Any ideas?
05-01-2011, 08:01 PM
#2
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Year: 1999
Model: Cherokee
Engine: 4.0
Spark + fuel (plus compression and air) = start.
You need to find what component you are missing.
If it doesn't even fire while cranking, check for spark. Remove a spark plug and keep it attached to the plug wire. Place the plug electrode near a good engine ground. Have a buddy crank the engine while you watch. You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.
If spark is good, then try a small amount of starting fluid into the intake. If the engine starts and runs momentarily and then dies, you have confirmed a FUEL DELIVERY problem.
Post back what you find. The above tests will tell you where to go from here.
If you have no spark at all, the #1 suspect is the crankshaft position sensor, followed by ignition coil and ignition control module (under the coil)
You may also want to try bypassing the ballast resistor on the fender. (cream colored). If it fails, it can inhibit fuel pump operation, although it usually allows the engine to fire a bit and then stops when you release the key as the ballast resistor is bypassed when the key is in the full right start position.
You need to find what component you are missing.
If it doesn't even fire while cranking, check for spark. Remove a spark plug and keep it attached to the plug wire. Place the plug electrode near a good engine ground. Have a buddy crank the engine while you watch. You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.
If spark is good, then try a small amount of starting fluid into the intake. If the engine starts and runs momentarily and then dies, you have confirmed a FUEL DELIVERY problem.
Post back what you find. The above tests will tell you where to go from here.
If you have no spark at all, the #1 suspect is the crankshaft position sensor, followed by ignition coil and ignition control module (under the coil)
You may also want to try bypassing the ballast resistor on the fender. (cream colored). If it fails, it can inhibit fuel pump operation, although it usually allows the engine to fire a bit and then stops when you release the key as the ballast resistor is bypassed when the key is in the full right start position.
Last edited by tjwalker; 05-01-2011 at 08:03 PM.
05-01-2011, 08:50 PM
#3
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Year: 1989
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Engine: Renix 4.0L
Well all the spark is good, I confirmed that before. It is a fuel delivery issue. I've gotta wait til tomorrow to get my fuel line pressure guage to see if my fuel pump is shot. You can't even hear the fuel pump prime up when you turn the key, so its the pump itself, or an electrical issue to it.
05-02-2011, 05:29 AM
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Year: 1999
Model: Cherokee
Engine: 4.0
1. Have you checked your fuel pump relay yet? There is one, although I don't know where it is on a RENIX.
2. Get a meter and check for power at the pump itself
3. Won't even need a pressure gauge for a basic test. Press on the schrader valve on the fuel rail, but if you don't even hear the pump energize and run for 2 seconds when the key is turned to the on position, as you mentioned you either have a fuel pump problem or control electronics problem for the fuel pump.
2. Get a meter and check for power at the pump itself
3. Won't even need a pressure gauge for a basic test. Press on the schrader valve on the fuel rail, but if you don't even hear the pump energize and run for 2 seconds when the key is turned to the on position, as you mentioned you either have a fuel pump problem or control electronics problem for the fuel pump.
Last edited by tjwalker; 05-02-2011 at 05:31 AM.
05-02-2011, 05:38 AM
#5
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
1. Have you checked your fuel pump relay yet? There is one, although I don't know where it is on a RENIX.
2. Get a meter and check for power at the pump itself
3. Won't even need a pressure gauge for a basic test. Press on the schrader valve on the fuel rail, but if you don't even hear the pump energize and run for 2 seconds when the key is turned to the on position, as you mentioned you either have a fuel pump problem or control electronics problem for the fuel pump.
2. Get a meter and check for power at the pump itself
3. Won't even need a pressure gauge for a basic test. Press on the schrader valve on the fuel rail, but if you don't even hear the pump energize and run for 2 seconds when the key is turned to the on position, as you mentioned you either have a fuel pump problem or control electronics problem for the fuel pump.
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