PLease Help, BIZZARE no start !!!!
javik
12-24-2005, 11:02 AM
Ok well my 91 limited is cranking but not fireing. At first it was just difficult to start, then sometimes i would try starting it for 5 min and get no start and then come back in and hour and it would start no problem and would start fine for next day or two. Now it will crank over but no bang no matter how long i leave it
What i have done so far
1. fixed Neutral saftey switch a while ago, but current symptons r not similar in that now it cranks, where as with a bad nss it did nothing
2. replaced battery, starter, cap, rotor, wires, plugs, Crank position sensor
what i have diagnosed so far
1. using the self diag mode i check for codes and got nothing, only a 12 and then the ending 55 (12 indicating no battery in the last 100 ig cyc seeing as i recently replaced battlery)
2. i stuck a screwdriver in coil wire and held 1/4 inch away from ground and was getting spark when turning over, also pulled plug and was getting spark there as well
3. am getting compression, checked fuel pressure and with vacum line attached to regulator am getting just under 40psi
4. tried pinching fuel line return after regulator for a couple sec to see if that would help and still got nothing
So i am baffled and just a numb nutz part changer. the wierd thing is that sometimes it would do this no start thing, which might have been indicative of a broke timing chain or something, but then if i let it rest? it would work the next day. Now i get nothing and i dont really know where to turn seeing that i seem to have spark and fuel, and crank but no bang.
What i have done so far
1. fixed Neutral saftey switch a while ago, but current symptons r not similar in that now it cranks, where as with a bad nss it did nothing
2. replaced battery, starter, cap, rotor, wires, plugs, Crank position sensor
what i have diagnosed so far
1. using the self diag mode i check for codes and got nothing, only a 12 and then the ending 55 (12 indicating no battery in the last 100 ig cyc seeing as i recently replaced battlery)
2. i stuck a screwdriver in coil wire and held 1/4 inch away from ground and was getting spark when turning over, also pulled plug and was getting spark there as well
3. am getting compression, checked fuel pressure and with vacum line attached to regulator am getting just under 40psi
4. tried pinching fuel line return after regulator for a couple sec to see if that would help and still got nothing
So i am baffled and just a numb nutz part changer. the wierd thing is that sometimes it would do this no start thing, which might have been indicative of a broke timing chain or something, but then if i let it rest? it would work the next day. Now i get nothing and i dont really know where to turn seeing that i seem to have spark and fuel, and crank but no bang.
mitre8
12-25-2005, 02:46 AM
I am having a similar problem with my 1996 Jeep Cherokee. I recently had the neutral safety switch replaced and had a tune-up with new plugs, wires, distributor cap and rotor, but still having this problem.
It seems to possibly be some kind of overheating thing because it happens after running around and if let Jeep sit for long time to let engine completely cool, then starts up, although sometimes sluggishly.
Thus, it seems to be some kind of safety shut down, maybe a lose wire or something else. I placed a post on this website today so hopefully someone will have some insight.
I would welcome any information that you may be able to provide if you are able to fix your problem.
Mike
It seems to possibly be some kind of overheating thing because it happens after running around and if let Jeep sit for long time to let engine completely cool, then starts up, although sometimes sluggishly.
Thus, it seems to be some kind of safety shut down, maybe a lose wire or something else. I placed a post on this website today so hopefully someone will have some insight.
I would welcome any information that you may be able to provide if you are able to fix your problem.
Mike
Gabewatt
12-25-2005, 06:49 PM
sounds like you have a bad starter mitre8. my old dodge does/did the same thing.
oljeeptek
12-27-2005, 06:01 PM
Sound like your not getting injector pulse. Do you have security lamp flashing on the dash at the time?
Is there an add on security system?
Is there an add on security system?
javik
12-27-2005, 10:23 PM
Sound like your not getting injector pulse. Do you have security lamp flashing on the dash at the time?
Is there an add on security system?
no flashing security light on dash, no other system that im aware of (i hate vats), and checked injectory pulse with meter and seems to be pulsing fine.
Am wondering if it is a fuel volume issue, has anybody else had a no start prob because of low volume despite having ok psi?
Is there an add on security system?
no flashing security light on dash, no other system that im aware of (i hate vats), and checked injectory pulse with meter and seems to be pulsing fine.
Am wondering if it is a fuel volume issue, has anybody else had a no start prob because of low volume despite having ok psi?
oljeeptek
12-28-2005, 01:37 AM
no flashing security light on dash, no other system that im aware of (i hate vats), and checked injectory pulse with meter and seems to be pulsing fine.
Am wondering if it is a fuel volume issue, has anybody else had a no start prob because of low volume despite having ok psi?
If you have 39 psi fuel pressure while cranking, your volume is fine to start. If you want to check further, it should be able toi fill a 16oz pop(Soda) boottle in 30 seconds or less.
If you indeed have spark, and injector pulse along with fuel pressure, try starting it on carb spray in the throttle bore. Use the flammable kind only for obvious reasons, and don't start a fire! Don't use starting fluid for this test. It's too harsh. If it starts, see if the injector pulse goes away while running on the carb spray. (This could indicate vats shut down).
If it runs on carb spray and has inj pulse, it's likely a ecu system issue. Under normal operation, the ecu looks first at the map sensor value to determine your altitude for main fuel mixing. Def map sensor will cause no start/hard start. Unplug it (3 wire connector) with the key off, and then try to start it. Your computer should be able to recognize it and go to default for the sensor input. It should set a map code, and will likely start if the ecu is ok and the map defective.
The second most important input is coolant temp input. If its reading too warm, you'll be too lean to start cold. It will probably run ok warm. Clear any codes then disconnect the coolant sensor and retry. Make sure it sets an open coolant sensor code.
The air temp sensor is only a trim input. It shouldn't cause a no start, more likely a harder or longer crank to start, and run wussy cold. You have crank (CPS) if you have spark. You do have nice BLUE spark, don't you?
If you can't start it this way, you have a timing issue, or a breathing issue plugged exhaust etc.
This isn't as easy as telling you to throw parts at it, but you can do these for free.
Am wondering if it is a fuel volume issue, has anybody else had a no start prob because of low volume despite having ok psi?
If you have 39 psi fuel pressure while cranking, your volume is fine to start. If you want to check further, it should be able toi fill a 16oz pop(Soda) boottle in 30 seconds or less.
If you indeed have spark, and injector pulse along with fuel pressure, try starting it on carb spray in the throttle bore. Use the flammable kind only for obvious reasons, and don't start a fire! Don't use starting fluid for this test. It's too harsh. If it starts, see if the injector pulse goes away while running on the carb spray. (This could indicate vats shut down).
If it runs on carb spray and has inj pulse, it's likely a ecu system issue. Under normal operation, the ecu looks first at the map sensor value to determine your altitude for main fuel mixing. Def map sensor will cause no start/hard start. Unplug it (3 wire connector) with the key off, and then try to start it. Your computer should be able to recognize it and go to default for the sensor input. It should set a map code, and will likely start if the ecu is ok and the map defective.
The second most important input is coolant temp input. If its reading too warm, you'll be too lean to start cold. It will probably run ok warm. Clear any codes then disconnect the coolant sensor and retry. Make sure it sets an open coolant sensor code.
The air temp sensor is only a trim input. It shouldn't cause a no start, more likely a harder or longer crank to start, and run wussy cold. You have crank (CPS) if you have spark. You do have nice BLUE spark, don't you?
If you can't start it this way, you have a timing issue, or a breathing issue plugged exhaust etc.
This isn't as easy as telling you to throw parts at it, but you can do these for free.
wwwildman
01-01-2006, 09:37 PM
Ok well my 91 limited is cranking but not fireing. At first it was just difficult to start, then sometimes i would try starting it for 5 min and get no start and then come back in and hour and it would start no problem and would start fine for next day or two. Now it will crank over but no bang no matter how long i leave it
What i have done so far
1. fixed Neutral saftey switch a while ago, but current symptons r not similar in that now it cranks, where as with a bad nss it did nothing
2. replaced battery, starter, cap, rotor, wires, plugs, Crank position sensor
what i have diagnosed so far
1. using the self diag mode i check for codes and got nothing, only a 12 and then the ending 55 (12 indicating no battery in the last 100 ig cyc seeing as i recently replaced battlery)
2. i stuck a screwdriver in coil wire and held 1/4 inch away from ground and was getting spark when turning over, also pulled plug and was getting spark there as well
3. am getting compression, checked fuel pressure and with vacum line attached to regulator am getting just under 40psi
4. tried pinching fuel line return after regulator for a couple sec to see if that would help and still got nothing
So i am baffled and just a numb nutz part changer. the wierd thing is that sometimes it would do this no start thing, which might have been indicative of a broke timing chain or something, but then if i let it rest? it would work the next day. Now i get nothing and i dont really know where to turn seeing that i seem to have spark and fuel, and crank but no bang.
My son's 89 was doing the same thing. Turns out it was the Crankshaft Position Sensor. It is located on the bellhousing at about 10 o'clock on the driver's side. There is a connector near the back of the fuel rail that goes to the sensor, it will be either 2 wires or three depending on the year. It is not that hard to replace if you lower the trans.
What i have done so far
1. fixed Neutral saftey switch a while ago, but current symptons r not similar in that now it cranks, where as with a bad nss it did nothing
2. replaced battery, starter, cap, rotor, wires, plugs, Crank position sensor
what i have diagnosed so far
1. using the self diag mode i check for codes and got nothing, only a 12 and then the ending 55 (12 indicating no battery in the last 100 ig cyc seeing as i recently replaced battlery)
2. i stuck a screwdriver in coil wire and held 1/4 inch away from ground and was getting spark when turning over, also pulled plug and was getting spark there as well
3. am getting compression, checked fuel pressure and with vacum line attached to regulator am getting just under 40psi
4. tried pinching fuel line return after regulator for a couple sec to see if that would help and still got nothing
So i am baffled and just a numb nutz part changer. the wierd thing is that sometimes it would do this no start thing, which might have been indicative of a broke timing chain or something, but then if i let it rest? it would work the next day. Now i get nothing and i dont really know where to turn seeing that i seem to have spark and fuel, and crank but no bang.
My son's 89 was doing the same thing. Turns out it was the Crankshaft Position Sensor. It is located on the bellhousing at about 10 o'clock on the driver's side. There is a connector near the back of the fuel rail that goes to the sensor, it will be either 2 wires or three depending on the year. It is not that hard to replace if you lower the trans.
javik
01-02-2006, 04:49 PM
well i think its the Idle Air Controller motor. Has anyone else had no start problems with a faulty IAC? well i have to wait for the part and then i will let you gys know how it goes.
oljeeptek
01-03-2006, 06:47 PM
well i think its the Idle Air Controller motor. Has anyone else had no start problems with a faulty IAC? well i have to wait for the part and then i will let you gys know how it goes.
The iac won't cause a no start condition. Its job is to provide for idle speeds above base idle. If it fails you could get no high idle, or higher then normal idle speeds. You should be able to start it by opening the throttle if the iac sticks closed.
You could also remove it by hand and compress the pintle (Center shaft) into the housing 1/8", and reinstall it.
It still sounds like your injector command is lean. You can see the pulse, but how wide is it? Have you tried a little extra shot of fuel when it won't start yet?
The iac won't cause a no start condition. Its job is to provide for idle speeds above base idle. If it fails you could get no high idle, or higher then normal idle speeds. You should be able to start it by opening the throttle if the iac sticks closed.
You could also remove it by hand and compress the pintle (Center shaft) into the housing 1/8", and reinstall it.
It still sounds like your injector command is lean. You can see the pulse, but how wide is it? Have you tried a little extra shot of fuel when it won't start yet?
javik
01-05-2006, 01:44 PM
problem solved
It was the combination of a dirty throtle body and the IAC motor gone bad. the motor crapped the bed in the full out position so the engine was suffocated and would not start.
From what i learned the IAC is not supposed to really comunicate with the pcm, but i took my other jeep and unplugged the iac and it would cause the exact same no start condition, even if i held the throttle open. very wierd, plus it wont give you a code that the iac has gone bad. Did not try pulling the iac but leaving it plugged in to see what that would do.
thanx for your gys input and i hope this helps whoever else has this wierd prob
It was the combination of a dirty throtle body and the IAC motor gone bad. the motor crapped the bed in the full out position so the engine was suffocated and would not start.
From what i learned the IAC is not supposed to really comunicate with the pcm, but i took my other jeep and unplugged the iac and it would cause the exact same no start condition, even if i held the throttle open. very wierd, plus it wont give you a code that the iac has gone bad. Did not try pulling the iac but leaving it plugged in to see what that would do.
thanx for your gys input and i hope this helps whoever else has this wierd prob
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