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Discussion Starter · #1 · (Edited)
So, happily rolling along and pow putt cough putt cough.....dead and coasted to the side of the road. Couldn't find anything obvious.

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Had it towed home and replaced the fuel filter and the fuel pressure regulator (I thought it was starving for gas).

It ended up being the fusible links just behind the passenger headlight near the battery.

My question is: Is there any downside to cutting them out and replacing them with more modern fuses?

For example,
Replacing this
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With something like this:
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Any reason to not do this? Any tips or suggestions? Seems more reliable and easier to fix if one lets go again, no?

Thank you in advance.

-Curtis
 

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1989 Trooper R/S
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I don't see why that wouldn't work. In the case of a momentary higher current, the fusible link might not fail where the fuse may, but then it would be so much easier to troubleshoot and replace the fuse. Just my thoughts, I mean they both would protect the wiring.
 

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The question is did the F/L BLOW, or did it fail because of a bad connection (corrosion)? If it blew, you'll obviously need to find out what blew it. From my experience, where F/Ls are usually a section of wire, a failed F/L usually has the insulation looking very puffy because of the heat that blew the link. Links are designed for more of a "slow blow" while fuses are a fast blow. You certainly could replace with fuses, but be sure to keep plenty of spare fuses as there are things (loads) that would blow a fuse, but not blow a F/L. Dennis
 

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Discussion Starter · #5 ·
Sorry in advance for the long post but sometimes there is value in the nuances of the details.

TL;DR Our final conclusion was the problem turned out to be a loose connection on the fusible link responsible for the ecm. It mimicked a fuel delivery problem such as a clogged fuel filter but was likely the ecm getting wonky and sending bad instructions.

(it was not a fun gremlin to find)

Details: The rig had been running great and I was driving merrily along when there was a sputter and loss of power and I pulled over to the side of the interstate. Tried to restart, sputter, would only stay running if I feathered and applied the throttle and would immediately die out upon lifting the accelerator pedal. Got it home and changed the fuel filter. No improvement. Then changed the fuel pressure regulator just in case. No improvement. Jumped the fuel pump relay with a wire and could hear the pump whirring on 12v power. I was far down the :"fuel delivery being the problem:" trail and convinced myself it had to be the fuel pump and replaced it. It wasn't. But it did give me a reason to cut the pump access hatch that I have seen many on this forum do. Should I need to replace it in the future, it will make the job far easier. After all that, no improvement and still wouldn't start.

At this point, I was feeling pretty discouraged. I am pretty good at rebuilding and maintenance but diagnostic trouble-shooting is a weak area for me. And here I had just finished rebuilding this truck to be my "super-reliable" one and it left me stranded. The loss of confidence was unpleasant to say the least. I decided to have a fresh set of eyes look at it and scheduled time with a mechanic here in my area. I paid for his time at his service rate to help me and we dove in. Initially it showed no spark but all the components tested fine individually. We measured the psi at the fuel rail and it was fine so it wasn't a fuel problem. The air delivery was fine. It was frustrating. After many hours we finally decided to wiggle every single damn wire we could find. When he moved the fusible links around, just a little bit, suddenly there was a blip of power. It was one of those "don't anybody move!" moments while you look at each other to see what variable changed. We cleaned all the connections well, re-tightened them and presto, it fired right up. The real bugger of it was we checked those earlier and since none were burned or puffed (like Dennis said) we thought they were fine.

In the long run, it ended up being a "who knows what is good and what is bad?" scenario. Bad that it broke down suddenly and left me on the roadside,. But good that at least the problem presented itself and there was no damage and no one was hurt. Also, the fact that it was not something catastrophic or "wrong" so to speak like major parts failure or something I installed incorrectly was oddly reassuring . It seems to have been literally just "one of those things that happens" kind of thing. It was expensive to pay my friend for his time but totally worth it. Sometimes you have to pay the expert for the lesson.

So now I am back driving it regularly and no problems or issues. Runs great. And I am slowly regaining confidence in it with each short trip. I wouldn't take it cross country just yet but we will get there. I am also toying with the idea of replacing the fusible links with fuses but Dennis's (DSUZU) point about "slow-go" and "fast-go" when fusing a circuit and electric load makes sense. I might just try to carry extra fusible links for now and watch it carefully.

As always, thanks for all the advice on this forum. I would not have the Trooper I have now without all the support from here. It is much appreciated.
-Curtis

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(My new access panel for the fuel pump)
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Agree with the value of details. Posts like this one can always be referred back to and are valuable for anyone who may experience a problem like yours. Fuse links that are hidden are forgotten and most may not even know there location as there usually trouble free. Good post and glad you have it fixed. The access cover for the pump is interesting. Where did you find it? And also does the cover for the fuse links just come loose by pulling straight up? I never accessed them.
 
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I will add the memory of this problem to future trouble shooting suggestions. Thanks for the detailed answer. Dennis
 
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Glad to see the problem finally resolved. Years ago I had a similar problem with a bad end on one of my fuseable links. Completely forgot about it until I read this. This is a great example of a rebuilt Isuzu. your attention to detail is amazing. I am kind of bummed you left Idaho but understand why.
 

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Great write-up. Filing it for future reference. I knew about the fusible links, but have never had a problem with them. Keep spares in the glovebox. And I'd always figured they were a go or no-go type thing. Good to know they can be intermittent. Question, what is the tan goop around the connections, some kind of sealing grease?

Mike
 

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On a tangent-- is that a factory brush guard that I spy?
 

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access panel looks great!!! where did you acquire such panel??? :D always looking for things to "add-on" for ease of access....
 

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Discussion Starter · #12 ·
Hi fellas,
I will try to answer the questions best I can.

Fusible link cover: It has a tab on one side and a flex clip on the other side. I used a small hook and it came off no problem but looks like the tabs could be broken pretty easily if not gentle.
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The goop: I am guessing it is some sort of white lithium/dielectric grease to protect against corrosion. That is just a guess though.
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The access panel: I wanted somthing that wouldn't rust and wouldn't impact the functionality of the cargo bed. I found this one, surprisingly enough, in the outdoor kitchen section on Amazon (link below). I really like it because it is stainless steel (the white in the photo is just the plastic cling wrap) and the closing latch gets tighter as it secures itself so it won't rattle around like an old gym locker or something. If you need the measurements for where to cut the access hole, I took photos of that as well.

Link to panel: https://www.amazon.com/dp/B0039BOVMU?psc=1&ref=ppx_pop_dt_b_product_details

Wood Rectangle Floor Asphalt Road surface


Brush guard: You have a keen eye! It is indeed a factory brush guard. I bought a headlight off a wrecked Trooepr from a gentleman in Oregon (back when I lived in Idaho). I noticed in his photos that he had another (much much rougher condition) Trooper hiding in the weeds behind it. But on it was this brush guard and bug deflector. We made a deal and he shipped it to me (worth it to me) and I repainted it. The factory ones just seem to fit the best, in my opinion. I added the chrome metal front bumper I pulled from a junkyard at a later date.
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-Curtis
 

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Ha! I own three Troopers and never knew that those were fusible links. I always wondered why someone had jumped some connections in the little black box! So, thanks for this post!
:LOL:
 

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Fusible links are less susceptible to surge currents and that is why they are used as main protection devices. Do not for any reason cut them out you will be doing more damage than good. Just replace the faulty one and it will last another 30 years.
 

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Very cool about the brush guard. The factory ones are much better looking than any of the aftermarket stuff (that doesn't really fit right). That's a nice grab.
 

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Very interesting, thanks for the detailed write up. Where can we get spare fusible links?

I'd like to add a brush(deer) guard to the front of ours!
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Very nice write up BoiseTrooper! It's always satisfying to figure out that sort of puzzle. This has me curious to know if there are other fusible links on our rigs.
 
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