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General Issues
Jeano - 6/5/22 at 10:40 AM

Picked up my new car and the fuse blew in the fuel pump and deaccleration once, changed the fuse then it went again under deaccleration at about 20mph going into the dartford tunnel. It was only a 20AMP fuse to after looking only i changed it to a 30AMP fuse as maybe it spiked and its been fine for about 75 miles.

After my first run out, a week later i found the car was dead and i had the entire dash out, i realised part of the fuse board was powered by a dedicated wire from the battery which was loose. So reconnected that and it was fixed.

Second run out, it blew a 5 amp fuel twice under full load (I carry a lot of fuses with me now). If the car is running and I pull the fuse it kills the car. I don’t want to take the entire dash and scuttle off again. What could it be? 5 amps isn’t a lot for anything. Its not the ECU as the power light stays on when I pull the fuse.

Slimy38 - 6/5/22 at 11:58 AM

Bad earths would be my first thought, higher voltages on certain circuits making their way on to lower powered circuits?

Check that all the chassis connections are sound, solid and not corroded.

David Jenkins - 6/5/22 at 12:03 PM

Bad earth somewhere is a good call - they cause so many issues.

Also, look for rubbing cables in the loom, particularly where cables go across metal parts of the chassis. Also look for cables rubbing against each other.

BTW: Changing to a higher-value fuse when the proper one blows is generally a bad move!

[Edited on 6/5/22 by David Jenkins]

gremlin1234 - 6/5/22 at 02:42 PM

quote:
Originally posted by David Jenkins
BTW: Changing to a higher-value fuse when the proper one blows is generally a bad move!


indeed a very bad idea, it means the loom becomes the fuse, and this can have disastrous consequences

Simon - 6/5/22 at 06:01 PM

quote:
Originally posted by gremlin1234

indeed a very bad idea, it means the loom becomes the fuse, and this can have disastrous consequences


A few years back we had a linisher that kept blowing fuses (internal rather than plug socket) so I cut down a six inch nail - lasted years like that. Then the building burnt down and we had to replace the tool.

perksy - 6/5/22 at 08:12 PM

Put the fuse back to the rating it should be as changing the rating to a higher rating is not a good idea

Check relevant earths and then give it a wiggle test on any suspect connections if need be after that

David Jenkins - 6/5/22 at 08:57 PM

Loose connections can also cause power spikes that can cause mischief...

Jeano - 7/5/22 at 06:49 AM

I hadnt actually changed the fuse yet so ill leave the lower one in there. Im going to change the fuse board as there is a loose power feed although its not linked to this fuse so dont think its that.

Hate electrics.

Jeano - 9/5/22 at 08:58 AM

Cleaned off all my earth points to the chassis, tightened my battery terminals and tidied up the loose power connection on the fuse block.

Did about 80 miles on sunday and alot under full load and it was fine.

Thanks for the motivation and feedback.

Im ordering new fuse block and connectors and going to tidy it all up over the coming weeks.

McLannahan - 9/5/22 at 11:52 AM

Saw these recently - obviously not a fix but would help a dodgy install until it could be properly checked, more of a get you home type fix!

Circuit breaking fuses for the car

https://www.ebay.co.uk/itm/321268071405