DirtyBomb

96 cherokee sport
cranks but wont start and i have pinned it to this fuse. its a 30a maxi fuse in the engine bay fuse box, but there are no labels, i dont have an owners manual and google has no answers for me on what it controls.

through my tests, i have found that i get no spark and no fuel with this fuse blown. strangely also, when i turn the ignition on, the a/c engages and the electric fan turns on :/

i replaced this fuse yesterday and it seemed to be running ok. it popped on my way into work today and i put 2 more fuses in, but each time they popped as soon as i cranked the engine.

can anyone tell me what this fuse is for and where i should check for problems?

audioal69

It's #2 here. Pic from my 96 sport owners manual

DirtyBomb

thanks audioal, that was very helpful. now what should i be looking for? im thinking maybe a short to ground somewhere, so just follow the wires coming from the fuse box?
maybe it has something to do with the family of rodents that took refuge in it over the past winter...

Bustedknuckle

Definitely a grounding issue if it pops the moment you key on. Follow the part of the wiring harness that loops down the right hand side of the motor, to the 02 sensor and CPS. That harness should be secured, but can come loose, and lean against the exhaust manifold, which will melt through the wire loom & wiring, and ground the wires out on the exhaust itself.

Also, I'd replace the ASD (Automatic shut down Relay) just for kicks and giggles. It works in tandem with alot of other maxi's and relays.

DirtyBomb

Found the white wire exposed on the upstream o2 sensor which i thought was the culprit, so i taped it up but its still popping the fuse. I think ive gone through 5 fuses now and at $3.50 a piece its getting rediculous.
Where else should i look? Im having the car towed home and ill hopefully have time to look over everything tonight

Willys55

It could be the ignition switch, I've had a few here in the shop just in the last two months with the same issue.

DirtyBomb

Is there a way to test this circuit without putting a new fuse in each time?

jronald

Yep
Buy a fuse pig tale that runs the 30 amp ATO style fuse. Put a couple of terminals on the wire ends and slide them into the holder for the larger fuse. The ATO fuse are about $2.00 for a box of 5.

Ron

jronald

Holder like this
http://cgi.ebay.com/30-amp-ATO-Blade...item27b7db1d60
Fuses like this
http://cgi.ebay.com/ebaymotors/FUSE-...Q5fAccessories
Crimp on terminals like this
Male version
http://cgi.ebay.com/ebaymotors/50-RE...item483e25ab57

Ron

DirtyBomb

Ignition switch, as in the spot where the key goes in?

jmxj

changed or having issues with your fuel pump before this happened? changed mine and popped that same fuse after running fine for 2 days. blew it every time i replaced the fuse, new fuel pump sender went bad that quick. easy test for it is unplug fuel pump electical connection by fuel filter, and see if you still pop the fuse when you crank it over.

DirtyBomb

He pump has been fine but i think the sender was having issues, idk if thats attached to the pump. My gas gauge has boon acting loopy for the last month or so, could that have something to do with this?

jmxj

sender is part of the pump assembly. if it is popping the fuse everytime you crank it, undo the electical connection for the pump / sender, it is located by the fuel filter, on the unibody rail, drivers side, underneath the rear door (look for the wires coming out of the front of the fuel tank and follow them until you come to a quick disconnect). once you disconnect it, try to crank it, if it blows the fuse, continue looking for issue, if it does not blow the fuse it is bad sender or pump.

DirtyBomb

I wonder if the pump was going bad and drawing excessive load. It was pretty loud when it was running

jmxj

did it end up being the pump that was blowing the fuse? if so, you may need a new pump, or assembly if it is the sender that is blowing it, when you pull it out take a look at the wires on the pump and sender. if the are broken or stripped you can try to fix them before getting a new pump, be careful with them, they should not touch each other or any of the pump assembly besides the wire connection when properly installed. here is what mine looked like. hard to tell but wires were shot after 20 years. did not try to fix, just went with new assembly.