15A Fuse keeps blowing? Please help!!

[pancake]

I found a local shop who diagnosed over the phone (spent 30 min with me) and said it is likely the Fuel Pump Module. Cost of replacing is $400 for parts & labor. Sound reasonable? Would this be hard to do myself?

 

[cal]

For 400 bucks.. I'd do it myself. It means dropping the gas tank but its not really rocket science.

 

[MJR]

I found a local shop who diagnosed over the phone (spent 30 min with me) and said it is likely the Fuel Pump Module. Cost of replacing is $400 for parts & labor. Sound reasonable? Would this be hard to do myself?

Haven't seen that before (11 years as a Jeep tech), but anything is possible. Dealer price that's probably about right. I'd still guess it's the wiring somewhere. As Cal said the fuel tank will have to be dropped, not too hard then you will either need the special spanner wrench to undo the lock ring or a huge pair of channel locks. It should come with a new seal and care should be taken not to roll the seal or cross thread the lock ring.


Mike R

 

[pancake]

Haven't seen that before (11 years as a Jeep tech), but anything is possible. Dealer price that's probably about right. I'd still guess it's the wiring somewhere. As Cal said the fuel tank will have to be dropped, not too hard then you will either need the special spanner wrench to undo the lock ring or a huge pair of channel locks. It should come with a new seal and care should be taken not to roll the seal or cross thread the lock ring.


Mike R

You want to fly up to WA?

I have an appointment with him tomorrow at 4pm to make sure that is the problem. I was surprised that he thought that as well. He said that it would be best to check it out before buying any parts. The dealer list price is ~$350 but my price (I get a discount there) is $280 for the entire assembly.

Any tips on where I could look (wiring) to find out?

 

[pancake]

Since he quoted ~$225 for the labor and $50 to do a basic check, it looks more like $550 total. This is killing me.

 

[MJR]

Barring anything coming up tonight I'll sit down and look over the problem again and maybe give you some areas to look specifically. Can you duplicate the fuse blowing, how frequent does it happen?


Mike R

 

[pancake]

Barring anything coming up tonight I'll sit down and look over the problem again and maybe give you some areas to look specifically. Can you duplicate the fuse blowing, how frequent does it happen?


Mike R

It’s strange. It seems that I can cruise all day long on the HWY and nothing happens, it runs great. The fuse blows most often while in reverse, but also while driving. It most frequently happens when I’m making a turn to the right over moderate rough road. If I put the XJ in reverse and backup quickly, it almost always blows it. Water seems to make it worse, but that is most likely my imagination…rain doesn’t affect it, mostly washing the XJ. I do need to replace my battery cables as the negative cable has corroded away quite a bit. I don’t see that as the issue though.

Everything else (ok, the backup lights don’t work all the time) electrical works in the Jeep. I’m very confused.

 

[MJR]

Ok I have looked at the diagrams again. You should start the jeep and wiggle test the harness to find the short. The power leaves the underhood fusebox and goes 2 places, the engine controller and from the fuel pump relay to the pump module.

First the wire going to the engine controller in the left fender goes through a connector near the firewall, back of the engine, right side. Start by moving the wiring harness just a little working from the fusebox and over to the engine controller. If you don't get any thing happening then we will move on to the other wire. I have seen the wiring short at the back of the engine area.

Next the wiring to the fuel pump will coming in through the firewall (I think it was the right side), crossover and exit to under the vehicle under the rear seat/carpet. You'll have to wiggle the trim panels along both sides and the rear seat. I have seen the wiring under the rear seat/carpet on the left side get cut. If you still don't get anything to happen you might remove the interior sill panels and wiggle/inspect the harness.

Also check the wiring underneath the vehicle where you can see it before it goes to the tank.


Mike R

 

[pancake]

Mike,

Thanks for the advice. I did as you said and performed a wiggle test on every part of the wire I could find. I wiggled the PDC, followed the harness (wiggled along the way, pretty hard too) across the firewall to the driver side along to the Engine Coltroller. Nothing happened.

I then tried to move around panels and carpet in the vehicle. I lifted up the rear seat and wiggled all the wires under there. I then went under the vehicle and wiggled the wire leading to the fuel tank. Nothing there either.

All this is while the engine was running of course. At the very end, out of frustration, I pulled on the wire harness (right next to the airbox) leading to the Engine Controller and this time the fuse blew. When I put in a replacement fuse it started melting the blades of the fuse (it was still very hot I guess) and finally blew the fuse before I could even start the Jeep. I had the key out of the ignition before trying to install a new fuse. After that first fuse blew, I put in another one and it started back up. I pulled on that area again and was not able to blow the fuse. There are a few ground wires there so I inspected very carefully...they all appear ok.

Do you think I should take this to a Jeep dealer? Would they be able to pinpoint this faster than a general automotive garage? So far this Jeep has been very dependable except for this fuse thing. It's very frustrating. Do you think there is any possibility the fuel pump module is causing this? It seems to start & drive just fine other than this, so it doesn't 'seem' like there is a fuel pump issue. Is there a way to test fuel pump draw to see if that is the issue?

I really do appreciate all the help.

 

[MJR]

All this is while the engine was running of course. At the very end, out of frustration, I pulled on the wire harness (right next to the airbox) leading to the Engine Controller and this time the fuse blew. When I put in a replacement fuse it started melting the blades of the fuse (it was still very hot I guess) and finally blew the fuse before I could even start the Jeep. I had the key out of the ignition before trying to install a new fuse. After that first fuse blew, I put in another one and it started back up. I pulled on that area again and was not able to blow the fuse. There are a few ground wires there so I inspected very carefully...they all appear ok.

Do you think I should take this to a Jeep dealer? Would they be able to pinpoint this faster than a general automotive garage? So far this Jeep has been very dependable except for this fuse thing. It's very frustrating. Do you think there is any possibility the fuel pump module is causing this? It seems to start & drive just fine other than this, so it doesn't 'seem' like there is a fuel pump issue. Is there a way to test fuel pump draw to see if that is the issue?

Sounds like you might be getting close to the problem. Usually you move the harness a little bit to isolate an area where it is. Once you have done that you might find it or you might have to take a closer look all around the harness in that area. Pay close attention to areas where the wiring runs through or by a sheetmetal edge. Just look at the area by the airbox where the wiring goes through to the front clip. I have seen wiring get cut and short on the front clip/fender area.

It's tough to decide who to work on it. Electrical can take a special kind of person to not spend a lot of time trying to find a problem or who doesn't want to just throw a part at it. I guess you could just go into a place and ask if they have anybody specifically that is really good at intermittent electrical shorts. It is possible someone has seen this problem before at the dealer (only if the guys have been there for a while). Some areas of the country have certain problems with vehicles because of enviroment/driving habits.

By what you said about the fuse blowing after the engine died and the first one was replaced I'd guess its not the fuel pump. Reason why is when the key is turned on the fuel pump will run for a few seconds then shutoff until the engine controller sees the engine cranking over. So when the engine died it should have turned off the fuel pump relay so if the pump was the problem the second fuse wouldn't have blown when you put it in. I think the next step should be to remove the fuel pump relay, turn the key on (you might get a check engine light so you will have to do a battery disconnect to reset it after you put the relay back in with the key off), and do the wiggle test on the underhood/front wiring. If the fuse blows at some point then all the fuel pump wiring and fuel pump itself is not the problem. You can then isolate it to the underhood area. I have become used to looking for areas where the harness goes by an area with sheetmetal edges or even seen spot weld flashing poking the wires and shorting out.



Mike R

 

[pancake]

Sounds like you might be getting close to the problem. Usually you move the harness a little bit to isolate an area where it is. Once you have done that you might find it or you might have to take a closer look all around the harness in that area. Pay close attention to areas where the wiring runs through or by a sheetmetal edge. Just look at the area by the airbox where the wiring goes through to the front clip. I have seen wiring get cut and short on the front clip/fender area.

It's tough to decide who to work on it. Electrical can take a special kind of person to not spend a lot of time trying to find a problem or who doesn't want to just throw a part at it. I guess you could just go into a place and ask if they have anybody specifically that is really good at intermittent electrical shorts. It is possible someone has seen this problem before at the dealer (only if the guys have been there for a while). Some areas of the country have certain problems with vehicles because of enviroment/driving habits.

By what you said about the fuse blowing after the engine died and the first one was replaced I'd guess its not the fuel pump. Reason why is when the key is turned on the fuel pump will run for a few seconds then shutoff until the engine controller sees the engine cranking over. So when the engine died it should have turned off the fuel pump relay so if the pump was the problem the second fuse wouldn't have blown when you put it in. I think the next step should be to remove the fuel pump relay, turn the key on (you might get a check engine light so you will have to do a battery disconnect to reset it after you put the relay back in with the key off), and do the wiggle test on the underhood/front wiring. If the fuse blows at some point then all the fuel pump wiring and fuel pump itself is not the problem. You can then isolate it to the underhood area. I have become used to looking for areas where the harness goes by an area with sheetmetal edges or even seen spot weld flashing poking the wires and shorting out.



Mike R

I'll try to give it a shot without the fuel pump relay. I'm not sure I made it clear, but after the fuse blew the 1st time I removed the key from the ignition, so everything was off. I then tried to install a new fuse, and that is when it started to melt the fuse blades and eventually popped the fuse. After that, I took that broken fuse out and installed a new one. The 2nd one didn't blow. I put the key back in and started her up. I did get a check engine light as I always do.

When I'm driving and the fuse blows, I do get the fan (electric??) to kick on. I'm really not sure that has any relation, just thought I would mention it. This might be a bit over my head, so I'll likely take it in. I'll try what you suggested first just to give it a shot.

When I take the fuel pump relay out I won't be able to start the vehicle correct? Just turn the key to the "on" position and wiggle around? It appears that all the wiring is wrapped in that plastic loom material. Would anything really be able to poke it?

Thanks Mike.

 

[MJR]

I'll try to give it a shot without the fuel pump relay. I'm not sure I made it clear, but after the fuse blew the 1st time I removed the key from the ignition, so everything was off. I then tried to install a new fuse, and that is when it started to melt the fuse blades and eventually popped the fuse. After that, I took that broken fuse out and installed a new one. The 2nd one didn't blow. I put the key back in and started her up. I did get a check engine light as I always do.

When I'm driving and the fuse blows, I do get the fan (electric??) to kick on. I'm really not sure that has any relation, just thought I would mention it. This might be a bit over my head, so I'll likely take it in. I'll try what you suggested first just to give it a shot.

When I take the fuel pump relay out I won't be able to start the vehicle correct? Just turn the key to the "on" position and wiggle around? It appears that all the wiring is wrapped in that plastic loom material. Would anything really be able to poke it?

Thanks Mike.

If the fuse blew the short was still there. Yes the engine won't run just have the key on. So you are saying the aux cooling fan comes on when the fuse blows? The plastic covering is split length wise to allow the wires inside and if that open section is exposed to a sharp edge or something poking it then its a problem.

Mike R

 

[pancake]

So you are saying the aux cooling fan comes on when the fuse blows?

Mike R

Yup, the aux fan comes on when the fuse blows. Well, it sounds like it at least...I've never actually looked to see. I can't think of what else it would be though. I'll try and take a look along the harness tomorrow evening. I had to change the oil in the motorcycle today and clean part of the garage.

I was just poking around with the fuse late tonight (the key was in the house, and I haven't driven the Jeep at all today) and I pulled out the fuse to check it. When I put it back I saw a very small blue arc. I would assume this means it is still running current even while resting? Since the Jeep had not been started in the last 24 hours...would this probably rule out the fuel pump? I haven't performed the latest test you advised me of yet, but I'll tackle that tomorrow.

Just curious. If I'm poking around the wire harness whiles the engine is running (or with the key out of the ignition)...is there a chance I might get a jolt? I don't want to get a nice little zap if you know what I mean. lol

 

[MJR]

Yup, the aux fan comes on when the fuse blows. Well, it sounds like it at least...I've never actually looked to see. I can't think of what else it would be though. I'll try and take a look along the harness tomorrow evening. I had to change the oil in the motorcycle today and clean part of the garage.

I was just poking around with the fuse late tonight (the key was in the house, and I haven't driven the Jeep at all today) and I pulled out the fuse to check it. When I put it back I saw a very small blue arc. I would assume this means it is still running current even while resting? Since the Jeep had not been started in the last 24 hours...would this probably rule out the fuel pump? I haven't performed the latest test you advised me of yet, but I'll tackle that tomorrow.

Just curious. If I'm poking around the wire harness whiles the engine is running (or with the key out of the ignition)...is there a chance I might get a jolt? I don't want to get a nice little zap if you know what I mean. lol

I'm just wondering if there is a PCM output that gets fed through that fuse the diagrams do show. It would be a lot easier if it was here that's for sure. Having it arc a little may not be abnormal since it probably reawakens the PCM. 12 volts isn't likey to give you much if any shock (unlike the ignition system).


Mike R

 

[pancake]

I'm just wondering if there is a PCM output that gets fed through that fuse the diagrams do show. It would be a lot easier if it was here that's for sure. Having it arc a little may not be abnormal since it probably reawakens the PCM. 12 volts isn't likey to give you much if any shock (unlike the ignition system).


Mike R

In the realm of long shots...this one is a beauty.

I've had this problem ~1.5 years (yeah, I know :lecture: ) and I believe it started pretty soon after I replaced the primary O2 sensor. As I was looking through my service manual (the generic Kragen variety) it 'looked' like the PDC connects to the O2 sensor. Ok, so it's a very LONG shot.

BTW I tried to wiggle that area again to fry the fuse and nothing happened. I swear, my ex is hiding under the hood just waiting for the worst time to pop that fuse. :hang:


You know, I might be driving down to San Jose in a couple weeks. Looks like Costa Mesa is a mere 424.0 miles farther south.

 

[XJRubicon]

well......?!!!!

What happened Its been a year?!!! Did you sell it or something?!@

My 99 is being a beotch like this now..... although.... its not back and fourth.

It killed out on the road on me so I wiggles ALL PCI connectors, Took out the dash, put it in, tried it, wiggled it and put it back in.... everytime nothing.

After about 30mins of jackin around, I found a fuse in the PDC that was blown. I put a wire between it as I had no fuses and it made a HUGE spark.... way more then 15 amps. I'm talkin like if you dead shorted the battery with a piece of wire off the old TV in the back of your XJ. :firedevil

So I'm on the side of the road in a canyon, no cell phone, 5 miles to cell range, 11:30pm with the fam.:firedevil

So I decide to just short the fuse with a piece of coat hanger, (I know bad Idea) to try and find smoke signals. but no smoke, I hear a faint sound of something boiling and the lights all dimmed for a second, (High amp draw) then the lights got back to their original brightness and the fule pump relay clicked and my girl heard the fuel pump run for a sec. I was like hell yeah.... I told her to try and start it and it fired right up! nice, killed it. Then I took just 3 strands of TV power cord wireand used the burnt fuse in another 15 amp location that had no prob. I took the good fuse and put it in the problem location just incase it wanted to show its ugly face again while driving.... I didn't want a piece of wire in there and have a fire. Drove home with no problem other then service engine soon light. I donno yet if it is because of all my monkeyin around before I found the fuse or not because I was unpluggin and pluging in everything.

Now today I gotta go get some fuses and try clearin that SES light.... but I'm pretty sure something fried out when I put the wire to the fusebox.

I'm hoping someone else has had this problem and knows what I fried

 

[pancake]

well......?!!!!

What happened Its been a year?!!! Did you sell it or something?!@

My 99 is being a beotch like this now..... although.... its not back and fourth.

It killed out on the road on me so I wiggles ALL PCI connectors, Took out the dash, put it in, tried it, wiggled it and put it back in.... everytime nothing.

After about 30mins of jackin around, I found a fuse in the PDC that was blown. I put a wire between it as I had no fuses and it made a HUGE spark.... way more then 15 amps. I'm talkin like if you dead shorted the battery with a piece of wire off the old TV in the back of your XJ. :firedevil

So I'm on the side of the road in a canyon, no cell phone, 5 miles to cell range, 11:30pm with the fam.:firedevil

So I decide to just short the fuse with a piece of coat hanger, (I know bad Idea) to try and find smoke signals. but no smoke, I hear a faint sound of something boiling and the lights all dimmed for a second, (High amp draw) then the lights got back to their original brightness and the fule pump relay clicked and my girl heard the fuel pump run for a sec. I was like hell yeah.... I told her to try and start it and it fired right up! nice, killed it. Then I took just 3 strands of TV power cord wireand used the burnt fuse in another 15 amp location that had no prob. I took the good fuse and put it in the problem location just incase it wanted to show its ugly face again while driving.... I didn't want a piece of wire in there and have a fire. Drove home with no problem other then service engine soon light. I donno yet if it is because of all my monkeyin around before I found the fuse or not because I was unpluggin and pluging in everything.

Now today I gotta go get some fuses and try clearin that SES light.... but I'm pretty sure something fried out when I put the wire to the fusebox.

I'm hoping someone else has had this problem and knows what I fried

Nope...never got it fixed. I tried messing around with the wires & such with no luck. For some reason it hasn't blown for a few months, but this post will probably change that. *sigh*

This has really ticked me off as it always happens at the worst possible time. You can't see it coming, just poof...gone. You're problem details are exactly as mine.

Maybe if we work together we can isolate it. 1/2 the work you know.

 

[old_man]

If it always happens, then pull the connector underneath back by the tank that provides power for the fuel pump. If it quits blowing you know it is the fuel pump.

 

[87manche]

also, once it's hapenned, unplug the ancillary plugs for the sub harnesses and do a continuity check to ground.
If you can at least isolate what part of the harness is shorting you can always run a new wire from plug to plug and bypass the damaged wire.

 

[XJRubicon]

Nope...never got it fixed. I tried messing around with the wires & such with no luck. For some reason it hasn't blown for a few months, but this post will probably change that. *sigh*

This has really ticked me off as it always happens at the worst possible time. You can't see it coming, just poof...gone. You're problem details are exactly as mine.

Maybe if we work together we can isolate it. 1/2 the work you know.

I got it!!!!

Did your jeep get stolen?!! When they stole my jeep they unscrewed the infinity amplifier under the back seat. It was just sitting in there with the wires connected. when we would hit a bump it would slid over and hit the fuel pump wiring harness. After wearing it down it started shorting. Finally two nights ago it stalled out on me and would not restart.

I crawled under the truck and unplugged the fuelpump, no change.
pulled the fuel pump relay, ding ding ding. no short.

was about to hardwire the fuel pump when i decided to look under the seat at the wires... Soon as I grabbed the harness for the fuel pump with the key on and a wire across the fuse, it arced out and I found the prob. the wires were not cut all the way so I taped them up and have not had a problem since.... gotta clear that ses light though

Check that harness, driver's side rear goes up under the carpet.

if thats not it you will have to trace that wire from there forward to the relay. has to be it man.