Wise Men and Women,

I'm totally embarrassed to admitt I had my car towed to the local experts when it wouldn't start on Monday. It turns out it's that fuse mounted in the engine compartment adjacent to the left hand wheel well. I don't need any lectures about what a bone head I am for not checking it as part of my troubleshooting, (I've already beaten myself up over that). But the weird thing is that the car was having a hard time starting earlier in the day. It's like the fuse started "going bad". I have a mechanical background and I have never heard of fuse "starting to go". In my experience a fuse either works or doesn't, like a light switch. So Anybody that could shed some light on that will get a cyber beer. Additionally, what would make that fuse blow in the first place? Is some other component drawing too much current?
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It's Jim (in Hartford CT)

As Art mentioned...if not violent, just elements. Usually road grunge/ age is culprit. Next time your in a local Marts type store/ auto parts store, pick up a waterproof (?) 25AMP fuse holder....I think I paid about $2.00 for mine. It's an enclosed item...holds one 25AMP fuse in a sort of jacket with a cap that fits over the top of the fuse. Takes a few minutes to swap out the original. Eleminates the worry of "gunge attack" on a vital fuse.

Enjoy.

I think that fuse and the fuel pump relay are tied for the #1 cause of 240 "no starts". The underhood fuse does indeed deteriorate because it draws a substantial current load and is not well protected from the elements - underhood heat, vibration, and moisture from road splash. On my '88, that fuse/fuse holder failed twice. The first time, I found the fuse had corroded and overheated, melting the fuse and fuse holder (and I got the tipoff from and IPD sales flyer). Years later, I was trying to sell the car for parts after it had been rear-ended, and I found that although the fuse indicated "continuity" on my digital multimeter, it actually had resistance in the hundreds of ohms - which minimized the current flow thru it. I can only speculate that heat and vibration took their toll on the fuse, since replacing it with a new one eliminated the problem. When you consider the dollar value of a fuse (measured in cents at the manufacturer level), think about just how much quality can be put into that component. It carries a heavy curent, so in my mind it's likely that hundreds or even thousands of thermal cycles embrittle the fusible element to the point where it no longer has the same low resistance it was born with. I could be all wet on this, but this engineer does a wholesale fuse replacement every 2-3 years as part of regular PM on his car.

That fuse probably did not blow, but its exposure to the elements caused it, the holder and wiring to the contacts to fall apart.

If it really did "blow", you should examine the blown fuse. If it shows signs of violence (burned) then you have a wiring harness problem shorting the wire to ground. If it just fell apart or sagged and melted, it was most likely due to the heat developed from a poor connection at the holder -- the most common trouble with that particular fuse. Actually, the fuse is usually OK, it is the holder and wire crimps that fail.
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Art Benstein near Baltimore

Thanks Art,

I did look at the fuse as part of my troubleshooting. But I didn't remove it. It "looked" OK, no violent burns like you'd see upon a direct short to ground. Thanks for the words. I'll take the new fuse out and clean all contact areas. I have another one around so maybe if the present one is beat up I'll use that.
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It's Jim (in Hartford CT)

Good morning,

If the fuse blows again...

I'm going to go out on a limb here and assume your hood hinges have been lubed through the years, and your hood isn't closing in that awkward way that some of them do with a high spot that allows condensation into the engine compartment along either side...However, if I am wrong, the blowing of the fuse could be moisture related, and as someone else stated, IPD has the cure.

Next, follow your wire from the inline fuse holder to where it disappears into the harness, now follow that portion of the harness to where it "rounds the bend" at the front of the driver's side strut tower; see that little metal "clamp" that holds the harness against that point? Right there, in that Volvo formed "crimp" or "crinkle" is where I have OFTEN found the problem of the regularly blowing 25amp fuse.

Hope this helps,

Chris

If you still have the original fuse holder, there's a bunch of stuff to clean. Inside the plastic body are contacts that adapt the spade lug terminals to the fuse, so including the wire crimps there are six electrical connections in that assembly hanging in the salt spray as a truck passes you.

Although I like to clean up the old one (it made it 15 years or so) most of those original fuse holders have been replaced by better sealed holders you can get from Radio Shack, ipd and other places. Something like this one:


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Art Benstein near Baltimore

Hard to say without knowing the year of the car.

If it's '86 or later, it could be the wiring to the O2 sensor heater. It runs under the car a ways and could be exposed to damage causing a ground short.
Being somewhat flexible, the problem could come and go.

Just a guess.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Thanks Bruce,

She's a 1987 245 5sp with 264,428 miles. A totally non rusty machine from New Mexico I had the pleasure of purchasing for a mere 700 bucks. The nicest 240 I've ever had.
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It's Jim (in Hartford CT)