whispers419
NAXJA Forum User
- Location
- Defiance, Ohio
Ok, I've only had this cherokee for about two weeks now. I bought it as a fixer upper. It was a hard start, but always started when I got it. Looked at it when it was running and saw the injectors spraying fuel all over the top of the engine and re o-ringed them, spray gone. It ran really rough after that, but still ran.
I realized I broke the vacuum line to the map sensor while changing the injector o rings. I replaced the vacuum line and for good measure also the MAP sensor. figured it was time, so I changed the plugs, wires, cap and rotor, and the coil. Started it up and drove it to my dad's house, with no problem.
Went out to leave, roughly 9-10 hours later and no start. It would fire and buck and jump around for a minute and stop, but wouldn't run... I checked the fuel pressure and there was roughly 5 pounds max. Checked lines and wiring, and then changed the pump and inline filter... now it has 40 pounds right away and stays there while cranking but no start....
I towed it home, so I could work on it a little easier. Checked the spark, and there was barely any spark at the coil wire, none at the plugs. Checked a few things and found the wire from the cps was up against the exhaust manifold, melted and grounded. I figured that must be the problem, changed the cps, the melted wire was between the cps and plug, so that was fixed too. Still no start.
Slightly better spark at the coil wire, but still an orange spark, when I test it at the plugs. I only get a spark with the gap very small and an intermitent weak spark. It has good fuel pressure, I believe leaky injectors or regulator, as the pressure slowly leaks off.
It would seem that the problem is the weak, intermitent spark, but what would cause it. ICM?
Here's a recap of what is new and known good.
MAP sensor
CPS
Plugs
Plug wires
Cap and Rotor
Coil
fuel pump, in tank and inline filters
injector O rings
The injectors could be leaky due to their new found pressure, but not enough to cause a no start. And that wouldn't cause the pathetic spark I'm seeing.
The weak spark is one thing, but the confusing part is that when I check spark at the coil wire, it doesn't seem to mis a spark, but when I check spark at the plug, it seems to miss a lot. I'm guessing this may be due to the spark just being weak enough it fizzles out when it gets to that point.
What other guesses do you have? ICM? Possible really worn, high loss contacts on the ignition side of the starter relay? Worn bushings in distributor causing shaft to have enough play to miss a cylinder now and then???????
I realized I broke the vacuum line to the map sensor while changing the injector o rings. I replaced the vacuum line and for good measure also the MAP sensor. figured it was time, so I changed the plugs, wires, cap and rotor, and the coil. Started it up and drove it to my dad's house, with no problem.
Went out to leave, roughly 9-10 hours later and no start. It would fire and buck and jump around for a minute and stop, but wouldn't run... I checked the fuel pressure and there was roughly 5 pounds max. Checked lines and wiring, and then changed the pump and inline filter... now it has 40 pounds right away and stays there while cranking but no start....
I towed it home, so I could work on it a little easier. Checked the spark, and there was barely any spark at the coil wire, none at the plugs. Checked a few things and found the wire from the cps was up against the exhaust manifold, melted and grounded. I figured that must be the problem, changed the cps, the melted wire was between the cps and plug, so that was fixed too. Still no start.
Slightly better spark at the coil wire, but still an orange spark, when I test it at the plugs. I only get a spark with the gap very small and an intermitent weak spark. It has good fuel pressure, I believe leaky injectors or regulator, as the pressure slowly leaks off.
It would seem that the problem is the weak, intermitent spark, but what would cause it. ICM?
Here's a recap of what is new and known good.
MAP sensor
CPS
Plugs
Plug wires
Cap and Rotor
Coil
fuel pump, in tank and inline filters
injector O rings
The injectors could be leaky due to their new found pressure, but not enough to cause a no start. And that wouldn't cause the pathetic spark I'm seeing.
The weak spark is one thing, but the confusing part is that when I check spark at the coil wire, it doesn't seem to mis a spark, but when I check spark at the plug, it seems to miss a lot. I'm guessing this may be due to the spark just being weak enough it fizzles out when it gets to that point.
What other guesses do you have? ICM? Possible really worn, high loss contacts on the ignition side of the starter relay? Worn bushings in distributor causing shaft to have enough play to miss a cylinder now and then???????
