Starting Issue (need some serious help)
01-07-2017, 05:01 PM
#1
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Year: 1999
Model: Cherokee
Engine: 4.0L Inline 6
Starting Issue (need some serious help)
hello, I don't know if this is the right place to post this or not so any help would be greatly appreciated.
I have a 1999 Jeep cherokee sport with 280,000 miles on it, I bought it for 50$ and I don't know any history on the vehicle but for 50 bones why not eh?
so to get to my issue its been running fine for about 2 years now. I've followed my own maintenance schedule, 3 months for oil changes and fluid checks so I think I generally care for the jeep.
the other morning I went to start the thing and I cant get it going.
the steps i have taken have been these:
Ignition:
I killed the battery trying to start it for two days thinking maybe just cold weather is the culprit its been in the teens lately, the engine does turn just fine no weird noises. i've since charged the battery.
Fuel Pump:
I checked to see if it was the fuel pump, turned the key on with someone else there and you can hear it for a few seconds. I also opened the gas cap and hit the pressure relief valve in the engine compartment to let out the fuel. closed up the cap, restarted the fuel pump and checked the relief valve again and fuel came out, so I would think its not the pump.
Fuses and Relays:
I went through all the fuses, none were bad. and checked the relays with a relay buddy relay tester with no bad relays.
I'm at a loss now. Its sooooo close to starting, it wants to but it wont. any help would be awesome. what should be my next step?
update: so i spent about 6 hours working on it today and heres what i did.
checked the computer for any codes and it was good.
verified spark and replaced all the spark plugs.
changed the ignition coil.
opened the distributer cap to see if there was any corrosion, it was clean and it does turn when the engine is cranked so it isnt broken.
checked fuel pressure and that was good too.
even sprayed starter fluid in it and it did nothing. the damn thing just wont start, getting frustrated.
Update:
Replaced distributer cap and the rotor inside, replaced all six spark plugs and installed a new crankshaft position sensor. Still no start.
Something did catch my eye though there were 4 wires that run out of the harness where the fuel injectors are that run down to an exhaust sensor that were all melted together spliced new wire to hook those back up. I don't know when that happened but maybe it's ruined some wiring to the injectors. But wouldn't the computer be throwing codes like crazy?
update:
its been a few days but tomorrow i'm going to undo the distributer all the way and check to see if the timing is correct, and also check the timing chain to see if its loose. my hope is that in the future someone else might have a full resource as to what i have tried and can follow the same steps.
I have a 1999 Jeep cherokee sport with 280,000 miles on it, I bought it for 50$ and I don't know any history on the vehicle but for 50 bones why not eh?
so to get to my issue its been running fine for about 2 years now. I've followed my own maintenance schedule, 3 months for oil changes and fluid checks so I think I generally care for the jeep.
the other morning I went to start the thing and I cant get it going.
the steps i have taken have been these:
Ignition:
I killed the battery trying to start it for two days thinking maybe just cold weather is the culprit its been in the teens lately, the engine does turn just fine no weird noises. i've since charged the battery.
Fuel Pump:
I checked to see if it was the fuel pump, turned the key on with someone else there and you can hear it for a few seconds. I also opened the gas cap and hit the pressure relief valve in the engine compartment to let out the fuel. closed up the cap, restarted the fuel pump and checked the relief valve again and fuel came out, so I would think its not the pump.
Fuses and Relays:
I went through all the fuses, none were bad. and checked the relays with a relay buddy relay tester with no bad relays.
I'm at a loss now. Its sooooo close to starting, it wants to but it wont. any help would be awesome. what should be my next step?
update: so i spent about 6 hours working on it today and heres what i did.
checked the computer for any codes and it was good.
verified spark and replaced all the spark plugs.
changed the ignition coil.
opened the distributer cap to see if there was any corrosion, it was clean and it does turn when the engine is cranked so it isnt broken.
checked fuel pressure and that was good too.
even sprayed starter fluid in it and it did nothing. the damn thing just wont start, getting frustrated.
Update:
Replaced distributer cap and the rotor inside, replaced all six spark plugs and installed a new crankshaft position sensor. Still no start.
Something did catch my eye though there were 4 wires that run out of the harness where the fuel injectors are that run down to an exhaust sensor that were all melted together spliced new wire to hook those back up. I don't know when that happened but maybe it's ruined some wiring to the injectors. But wouldn't the computer be throwing codes like crazy?
update:
its been a few days but tomorrow i'm going to undo the distributer all the way and check to see if the timing is correct, and also check the timing chain to see if its loose. my hope is that in the future someone else might have a full resource as to what i have tried and can follow the same steps.
Last edited by masteroguitar; 01-12-2017 at 07:55 PM. Reason: update.
01-08-2017, 08:47 AM
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s346k is right. Make sure you have good spark. Also check fuel pressure with a gauge. Just the presence of fuel doesn't mean you have enough fuel pressure. Fuel pumps on the way out can often still deliver fuel but not enough pressure. If you don't have 45/50 psi on the rail start with your fuel filter and recheck before going after the pump. And check it under crank, not just koeo.
01-08-2017, 05:41 PM
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Sounds like you need to begin checking your injectors. They are unlikely bad, but you'll need to verify pulse. You can check it with a test light, but a noid light is definitely the easiest and can be done solo. If you aren't getting injector pulse, you won't start. I assume you sprayed starting fluid into the the throttle body. If the injectors aren't pulsing there are no avenues for the fluid to enter the combustion chamber. The sensor ballet between the crankshaft sensor, the camshaft sensor, the TPS, and the MAP can be a bastard to definitively diagnose, but those are going to be the primary actors in a no injector pulse situation. In my experience the crankshaft sensor is the most likely culprit. The hall effect system these jeeps run on is at best a questionable design.
01-30-2023, 01:36 PM
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Is your temperature sensor working?
Sounds like you need to begin checking your injectors. They are unlikely bad, but you'll need to verify pulse. You can check it with a test light, but a noid light is definitely the easiest and can be done solo. If you aren't getting injector pulse, you won't start. I assume you sprayed starting fluid into the the throttle body. If the injectors aren't pulsing there are no avenues for the fluid to enter the combustion chamber. The sensor ballet between the crankshaft sensor, the camshaft sensor, the TPS, and the MAP can be a bastard to definitively diagnose, but those are going to be the primary actors in a no injector pulse situation. In my experience the crankshaft sensor is the most likely culprit. The hall effect system these jeeps run on is at best a questionable design.