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ongoing issue and now I'm stranded

S

Superflie

NAXJA Forum User
Location
SLC, UT
I have been chasing an issue with my 91 xj for two years now. I'll be driving along and it will start hesitating repeatedly. I found a wiring and grounding issue and its been fine for 6 months. I've checked and my fuel pump is working fine and I have spark at the plug. It will catch for a split second then hesitate a few times and die. I'm not sure if it has any bearing or not but the fuel gauge stopped working about the same time I started having this issue. Anyone please help! I'm stick in bear lake
 
Get a spray can of starting fluid.
See if the engine will run whil sprating that into the intake.

My original fuel pump (1991) gave out this past year.
It ran with the key on, had suffficient pressure at idle.
But the Jeep would not go over 30 mph.
 
So it won't start right now and you have verified spark?

Is it a strong, blue, snapping spark? Yellow or orange indicates a weak spark which may not be enough to start the engine. For weak spark, suspect the ignition coil.

If spark checks out, then I agree with the suggestion of spraying some starting fluid into the intake. It is a quick and dirty way of determining if you have a fuel delivery issue. Just because you hear the fuel pump run and you have pressure at the schrader valve on the fuel rail does NOT mean that you're getting fuel to the injectors.
 
Have you bypassed the fuel pump ballast resistor on the driver's side fenderwell? Have you tried swapping the relays around--mark them first so you can get them back to their original positions. Do you have a NOID light so you can check if the injectors are getting a firing impulse from the ECU?
 
Sounds like a intermittend CPS.
 
i tried starter fluid and got nothing, i did check the spark but it wasn't blue. I replaced the CPS a year and a half ago so it should be ok, same with the ballast resistor. Which relays would i swap around? I'll have to research the NOID light, i dont have one and don't know how to use one.
 
Low cranking voltage, possibly. Check the static voltage at the battery between the terminals, then when cranking. Looking for about 12.5 volts static, and 9 volts or above when cranking.

Poor cap and/or rotor, poor spark plug wires.
 
my battery is a year or two old, but its one of those autozone gold jobs, supposed to last a decade or so. How likely is it that this is related to my fuel gauge no longer working? cause from what i can see, a CPS causes that to go out. The fuel gauge has been out for almost 2 months now and my xj's been running fine except every once in a blue moon it chugs a bit then back to normal. When i initially turn the key after its been sitting it acts like its about to start then just cranks or even starts for a split second then dies. Is the CPS the only thing that would cause that gauge to go out? the wires look fine at the fuel pump. oh and the plus rotor and cap are all 6 months old
 
No connection between the CPS/CKP and the fuel gauge. A shorted CPS/CKP will sometimes keep the diagnostic port from making contact with a code reader/scanner.

You need to check the available voltage, regardless of how old a battery is. Alternators fail, cables get corroded, grounds go bad, and you end up with a discharged battery. Once the voltage drops below 9 volts your electronics are going to get crappy.
 
Superflie said:
I have been chasing an issue with my 91 xj for two years now. I'll be driving along and it will start hesitating repeatedly. I found a wiring and grounding issue and its been fine for 6 months. I've checked and my fuel pump is working fine and I have spark at the plug. It will catch for a split second then hesitate a few times and die. I'm not sure if it has any bearing or not but the fuel gauge stopped working about the same time I started having this issue. Anyone please help! I'm stick in bear lake
Click to expand...

I had trouble with my truck hesitating on the freeway going about 40-45 or so. NO trouble otherwise. It would chug, hesitate and then be fine. I tested my TPS sensor and it turned out to have a few dead spots in the range of motion, along its sensor strip.

This was the original part, as far as I could tell. I paid the $30.00 and got a new one, and blam, no more issue.

With a large enough dead spot, I don't see why it wouldn't just stop, but would still be able to be fired once the truck was as a standstill.

:shhh:
 
So..... I bought a cps and an ignition coil and drove up. Tried the cps last night and that was not it. Gonna try the coil this morning
 
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