wagon58

Hi I have a 1996 GC 5.2v8 4x4. I recently parked it for a month, now I can't get it to fire up.
A few details.
1) the battery was completely dead, had to recharge it
2) I pulled of a couple wires and checked for spark --- nothing
3) the fuel gauge shows that it doesn't have gas, but it does I added 8 gallons
4) I recently had the drivers door panel off, but I double check all of the connections
5) I went ahead and put on a new dist cap and rotor (my jeep eats these things)
6) I put a new coil on last year.
7) I shot some starter flood down the intake, nothing

What are the next steps to debug? do we have a thread for that(I couldn't find one)?

ZJMAX

Not sure about your year but I would check if it has a crank shaft position sensor.

Max

munyanb

check your fuses, crank position sensor, wire connections everywhere Got any codes showing? did the fuel gauge work before?

wagon58

yes, the fuel gauged worked before. In fact everything was working fine before I parked it.

munyanb

Check all connections and fuses, hopefully its not your ECM , honestly I had an electrical issue going on that I couldn't figure out, no dead battery , but believe it or not it was my alternator going bad, I rebuilt the alternator and its all fine, before that I had crazy stuff going on and unplugged everything and used contact cleaner everywhere, even the ECM plugs. And ive read on forums there is sometimes a screw that shorts the ECM , Your problem almost has to be a bad connection, even at your battery terminals possibly? What kind of climate do you live in? How clean is your jeep? mud and dirt attract moisture.

wagon58

Texas - but it's been raining a lot the last 2 months - very humid here. It's a clean engine - 180000 miles but has been solid. I have changed the crankcase sensor, camshaft sensor about 2 years ago.

munyanb

So did you check fuses? unplug and plug them back in? Check your grounds also.

wagon58

yep - checked the fuses - pulled the all out and cleaned the connections, rotated - nothing. It's really strange - at least to me - that when I turn the key on the fuel gauge is dead.

wagon58

one other thing - my code reader cannot "make the link" to the car

97grand4.0

Huge sign of a bad pcm. take the connectors off and spray with contact cleaner. Done any poking around with a volt meter, you know, to see if the fuel pump should be running and is not? or if the coil is getting voltage?

munyanb

Can the PCM go bad while sitting? were jumper cables ever hooked up, ive heard of frying computers by jumping them from other vehicles, I haven't had that happen to me yet but ive heard of it. Im still leaning towards a bad fuse or bad connection or even bad ground but would like to see a schematic. I had an alternator going bad that caused me all sorts of grief two months ago, it would do all sorts of weird things. but the battery was charging still. sometimes my voltage went to zero, then max, then the fuel gauge wouldn't work, then it would, I ended up buying a 15$ rebuild kit and its fine now. it seemed like the two leads to the brushes are isolated throughout the system, but like I said id like to see a schematic. One of my brushes were almost completely gone, not sure how it worked at all really. I remember you said you tried ether to get it to fire or dumped gas right? but is the fuel pump running, is there pressure on the fuel rail? if the PCM is not bad it cant be anything besides bad connections somewhere. I had a ground issue as well on mine before. The one on the side of the engine block.

dave1123

The first thing that came to mind is you said your jeep eats distributor caps. That's a sure sign of bad bearings in the distributor shaft. It allows the rotor to wobble, causing it to strike the cap. It can also effect the signal from the cam sensor.

You won't have power to the coil or fuel injectors and fuel pump until the ASD and Fuel pump relays turn on. THAT won't happen until the PCM sees a CPS signal. The PCM turns the fuel pump on for a couple of seconds to charge the fuel rails when you turn on the key, but shuts off until told to turn back on by you cranking it.

After all that, it appears you have a problem with either no signal from the CPS or a PCM not active. Either one of those could just be a corroded connection.

wagon58

I did try and jump start it - the battery had drained down to nothing. Is there a fuse for the PCM? if so where? The fuel pump is not running. I haven't checked coil voltage yet.

dave1123

I believe it's fuse 21 in the box under the hood (PDC). It's for the PCM and ignition coil. 20A

wagon58

OK issue solved - It was my PCM. I bought a re-manufactured one from autocomputerexchange on ebay - $140. As soon as I hooked it up the gauges started and the beast fired up. After a nice 1/2 drive the engine settled in and it's running better than it has in a while. Thanks for all of the help here! I'm not sure what caused it to go out - it was just sitting in the drive way. Maybe just corroded up or when I jumped it - that fried it - IDK.
But it's on the road again - and only 180K on the odometer

Thanks All!