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88 Cherokee 4.0 Auto - Wont Start

D

Desert Jeepin

NAXJA Forum User
Location
Ridgecrest/Edwards AFB, CA
New Ignition Module
New Coil
New FP
New FF
New CPS

Now what?

It used to start if I let it sit a while, but now it wont start at all. Back in the day, only like 1 in 500 times would it not start, or it would start/die but then restart just fine.

Now it wont start at all. It cranks strong, but wont fire.
 
I'm not sure how to check the NSS, but I posted in another thread asking wether or not it would "Crank" with NSS problems, or if it would just click.

I have not yet checked spark. I intended to today, however we have 30+ mph winds and I am afraid to open the hood, quite frankly ;)

As for teh fuel issue, I have only checked that twice. I hit the valve on the rail and got nothing. But after letting it sit for ~4hrs, I turned the key and it fired right up.

On a later attempt to start, it would not. I hit the vavle again, and got gas at pressure. I figure the pump is working, but maybe not the relay??? Even if the FP regulator was bad, I assume that it'd re-build the pressure and eventually start.
 
If it cranks the NSS is okay.

Checked the fuel pump ballast resistor? Do you have fuel pressure? It requires three things for an infernal confusion engine to start and run: fuel, air, and spark. Some folks add compression as a fourth requirement, but that's a lower-level requirement.
 
I have tried jumped the two wires on the Ballast Resistor together, but no joy.
 
I've shorted the resistor, and no luck. It cranks, so that rules out the NSS right?

Not sure how I would go about checking timing. I havent got a light, and the Jeep is at work :(
 
mine fires up with the resistor unplugged and then shuts down about 5 sec later and the NSS wont let it crank at all so I would say it has to be something else.

Dan
 
Ok, I've played musical relays...

Why??? Because now there's no fuel at the rail.

Where do I start?
 
fuel pump... fuel relay... you can DIRECTLY wire the fuel pump... get under the tank, and add 12v direct... mine crapped out and had to replace it...

fyi it was about 80 bux and about 2-3hrs to fix... i tried doing it in place but forget it, its easier to just drop the tank....

JOe
 
Which of the wires do I need to add 12V to, assuming I'm not getting it and should?
 
Ok, so I check the Ballast Resistor, No voltage on either side.

Simple solution, jumper 12V from the battery to the rear-most wire. Hit bleader on Fuel Rail, and I got fuel, well a drip, which is more than I had. So I let it sit a second and hit the bleader again, no fuel.

What's between the Ballast R and the Pump? Is it just a straight shot from there?
 
I have not replaced it.

I'm getting no voltage to either side of it.

I "added" 12V to it and still get little to ZERO fuel.
 
So, with the 12V "Added" to the resistor, I traced voltage to the pump. I have the 12V at the pump on the larger WHITE wire.


No fuel pump noise.



I guess the pump is bad. :rattle:
 
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