Bk.randy

So, this is probably gonna be a book, I just hope some fello Jeepers will read through it all and could possibly shed some light on what the hell is going on with my, about to be ashes, Cherokee. To be clear, 1996 Jeep Cherokee 4.0l 4x4 automatic. Okay, so one day I go out to the driveway in the morning, start the Jeep. Starts fine, runs for about 5 minutes while I’m loading up with some stuff. Then it stalls. No stumbling, no warning. Just straight dies. Idle to nothing in a snap of a finger. Thought to myself, wow that’s really strange, never happen before. Reach in, fires right back up. Repeated the same sequence of events 3 times until it finally kept running. So I leave, drive about 5 miles, shut it off when I got to my first stop for the day. Left it sit about a half hour, Jump in, fires right up like normal again and I leave. Drive another 10-12 miles to my next destination. Shut it off, sat for about another half hour. Jump in, fires right up. At this point I thought I was in the clear, just some wonky **** going on that didn’t mean anything. Drive 15-20 miles back to my town, stopped, shut it off again, filled it up with gas. Jumped in, fired up again. Still no issue, get about a mile up the road headed home. Start wanting to die. Tach is going nuts along with the engine, losing power. Rpms just continued to fall. Tried downshifting to bring the rpms back up, no good. Wouldn’t come out of it. So I just let it shut off and coasted to the side of the road. Tried to restart it, NOTHING. Just cranks without a single fire. Drug it to my buddies house just up the way. Noticed the fuel pump wasn’t priming. Figure, AH, that’s my problem. Waited a few days, got a pump. But before I put it in, just for ****s and giggles. Tried to fire it up again, see if maybe I could get it to my house to changed the pump. Thought I’d get lucky. Well I did, sort of. To the key, heard the pump run. So I tried to start it. And it tried very hard to start but all I could get out of it was a few sputters here and there, not even enough to hear the exhaust but I could tell it was getting spark still at this point in time. But it would just sputter 100 or 200 rpms and wouldn’t just fire up. So I gave up and just changed the pump at my buddies, figured maybe I wasn’t getting enough pressure or something.

After I put the new pump in, I was excited I’d have my Jeep back and it would be normal. Wrong! New pump now wouldn’t run on the key. So I was pissed as you could imagine. Figured, what the hell now. So I start monkey with some stuff. Decided, we’ll I’m gonna spray some starting fluid down the ol’ throat, see if it’ll bark off on that anyway. NOPE! It was at this point i realized I didn’t have spark anymore either! Now I’m really wondering what the hells goin on. So I went and bought a spark tester and fuel pressure gauge to verify everything, which I did. No spark or fuel. So I started messing with relays and test lights. Had constant 12 volts to the bottom pin of the pump relay, also 12 bolts to the accessory with key on, good ground, checked with a multi meter. Relay didnt click on turn of the key tho, so I swapped it with the starter really I knew worked. Still no click. Tried the starter in the relay I just swapped in from the pump, worked fine. Also started to think I got a faulty pump. So I jump a wire from the constant power pin to the activation pin, pump ran. Put 50 psi up to the rail. So Being confused as all hell, I started googling. Found some info on the ASD relay/circuit. Read that when it activates it shuts off fuel and spark. So I thought for sure that was gonna be my problem. See I changed that relay, also tested my power to the sockets. Has 12 in constant pin, and had 12 in the accessory pin. And with new relay, changed nothing. Still no spark or fuel.

Now, I just finally brought the thing home after a couple months. So I can work on it in the garage. And having left it sit for a couple weeks since I last tinkered on it. Went back through and tested all my power, fuses (inside and out), relays fuel pressure, spark. Nothing changed. Until I was inside checking the fuses under the drivers side dash. Poking them all with my test light, they all worked like I said, BUT, after I was done, I turned the key back off, then back on again. THE PUMP PRIMED! I didn’t believe it, so I cycled it again, then a third time. It primed all 3 times! So I then tried to start it, and lucky me, I had a bad buttery connection bc I had only set the terminals back on without tightening them, so I hear a pop, lost all power like I unplugged that battery, happens all the time with bad connection. So I then tightened my terminals. Went back to see if I still had my luck. NOPE! Pump no lingered primed with the key. Instantly pissed me off, so I went back under the dash, started poking the fuses again, thinking maybe one popped or wasn’t tight enough in places. All fuses checked out yet again, inside and out. Still had power in my relay pins. And out side fuses. Just now, the pump no longer primed.

Something I should mention but forgot about, I I did too buy a new crankshaft position sensor. Installed it as well and had no effect on anything. So to sum it up. The only things I replaced was the ASD relay, fuel pump, and crank sensor. Nothing else. And thought the whole progress of trying to diagnose my problem only only got it to try and fire again with the original pump and crank sensor. After I changed them both, the pump only ran again off the key 1 time recently after bringing it home, and have not had spark again to my knowledge. I might’ve the time I got my pump to run off the key today but thanks to my lazy battery installation I’ll never know. I’m just hoping somebody can give me something to work with here, bc I’m out of ideas, I’ve had that test light and multi meter all over that Jeep and can’t find any issues with grounds related to fuel pump or fuse panels. Everything else works as it should. I’ve checked the cap and rotor as well, look fine. Wires are new, same with plugs. Ignition coil doesn’t seem to work but I can’t imagine it would be bad all of the sudden if I can pull fuel either. I still think it something to do with a circuit they run off of together, causing me not to have spark or fuel. Which was why I thought for sure it was the ASD, but as far as I can tell it checks outs. Had power where and when it needs it and a ground with a new relay so, I’m just stumped. I have paper thin patience at this point after 2 months of messing with it. Getting no where. As always, any input is greatly appreciated, more now than ever, considering lol.

agreen

Clean your grounnnnnds!

It really does sound like an intermittent ECU ground issue. The ECU provides the ground path for the relay signal.

By the sound of it, you might not be getting a good ground intermittently, causing no fuel pump and no ignition. There are many threads on how to clean your ground points. One of my favorite ground cleaning tools is what's called a "bonding brush". It really makes short work of corroded ground points, plus it makes a neat, tidy contact pad.

Bk.randy

Im not very good with wiring at all, which is why this issue frustrates me so much. There’s probably a lot of grounds for various things on that Jeep. What grounds should I start with, and where more importantly? I read that ASD relay grounds from the computer and it too will control the circuit that operates the ASD relay. I wouldn’t have a clue what to do there, and as far as anything else I should clean, I just need locations to look. I can’t read schematics so those don’t do me any good. I just don’t wanna go around cleaning everywhere a black wire leads if some aren’t gonna do me any good cleaning with the given problem, know what I mean?

awg

search this forum for ground locations.

There are 2 big ones with multiple connections on the engine block near distributor and dipsticks, they are where the PCM is earthed

it is possible you have defective main earth cable from the battery

its worth downloading the '95 FSM and studying section 8D that describes the sequence of start up operations

a non -genuine Crank sensor or bad wiring to it can be an issue

try unplug front O2 sensor...any shorts in wiring will mean the sensors dont get 5V reference...probe some sensor power wires to see if you have 5V

I believe a failed cam sensor can also cause the same symptoms as a failed crank sensor (not sure though, I will let others comment on that)

agreen

agreen

Bk.randy

The two grounds under the coil could definitely be culprits. They’re pretty rusty. Gonna have to do some tearing to get them enough to clean them. I always noticed how rusty they were this whole time but had no idea what they were for.

The only part that still has me confused is how I was under the dash moving things around and poking away with the test light and only after doing that did the key operate the pump again. I figured maybe it was something under there that would be my problem but cleaning those grounds under the coil sure couldn’t hurt anything. Like I said, they’re nasty so I’m the least I’m doing the Jeep a favor.

BruceB

If you care to read about a similar experience and the solution:

https://www.cherokeeforum.com/f2/sen...roblem-251669/

Bk.randy

Found where my issue lies everybody! It’s got something to do with the harness at the passenger side fire wall, about 3 or 4 plugs there, don’t remember for sure. They sit basically right above the ground by the oil dipstick toward the back of the block, start digging through there looking for broken wires and I had they key on while doing so, pulled on a few wires and the pump kicked on again, got in with a tight battery this time and fired right up. When I went back and started messin with them wire again it died on me again but it’s gotta be a loose connection in that harness some where. Followed it alittle bit, goes down beside the transmission (passenger side) and eventually ends at the front of my driveshaft to a plug not even being used. It’s just zipped tied to the E brake line, always was since I had it. So I’m hoping someone can elaborate on what this harness contains bc I didn’t figure it would have had anything to do with fuel or spark, I was just taking a long shot. Sure at **** tho, my problem lies in there. Anybody got any input??

awg

I strongly suggest you download the FSM from cruisers website, as it identifies all plugs and wire colors

if not, you need to upload a picture, or at least advise the plug color, shape, terminal number, and wire colors, then we can help you

mostly they are transmission plugs, but maybe one is the fuel pump harness

OutbackOz

might be the pcm?

Bk.randy

I haven’t been able to work on it the past few days but the next time I get a chance I will get that info, if not a picture. Best description I can give you at the moment is there is 3 circular plugs, white in color and each have between 4 and 6 wires running in to them. The particular plug I think contains whatever issue I have is black and more rectangular, although have rounded edges. It is with all those other plugs. If I pull on that plug, (pulling the wires with it of course) up towards the hood, the fuel pump replay clicks and the pump runs. But if it falls down far enough it kills the Jeep again instantly.