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[Essex Pete]

The other day i was checking out the ECU to check what part number it was. When i opened the ECU cover, i noticed the fuel pump relay (brown one) with the 20a fuse mounted next to it.  This fuse was well and truely melted, and i mean melted, the plastic covering was moulded to the fuse holder.  i managed to prise the remains out and fit a new fuse, which seems to be ok.

Im curious why the fuse would have been in that state though?  The car had been getting more difficult to start recently, and on Monday morning i had to crank it over for a long time before it fired up.  Since putting the new fuse in it seems to start up much better, but i really cant see a reason for it being in that state.

Sorry for the essay, but i was wondering if any others have views on it. 

Cheers, Pete

[Dave DND]

Assuming the correct value of fuse . .

I have seen fuseholders before with either tarnished or corroded terminals, and this gives a much higher resistance across the contacts, but not enough to go open circuit and cause the fuse to fail. The side effect though, is that the fuse contacts will heat up through poor connectivity but never quite pull enough current to blow the fuse.

More common than you think, but people rarely notice it until its too late.

 

[candyman]

also i have seen where the fuse is constantly running at 20a and not enough to blow but the heat melts the plastic. see it on trucks all the time when a driver puts a 20a in instead of a 10a in the fuse box. then the yellow plastic melts cause theres a short in the back of the trailer somewhere but due to lenght of cable it wont blow fuse.  id check wiring to your fuel pump etc incase of corroded or chaffing wires etc. feel the new fuse once running to see if it gets warm as well, it should be fit to touch and hold on to.

[shammster]

And it might be worth your time to take out the other fuses and clean the contacts with a bit of emery.
Pulling the fuses out and in also helps clean the fusebox contacts.