TRF Forums

On Saturday I was meeting with the boys from Wiltshire, after unloading the van in the lay by I hit the starter and the bike turned over and primed the injector, on 2nd push it attempted to fire but didn't, after that it was completely dead...no noises, no injector priming - nothing. We tried all the obvious including swapping fuses around but no joy

So I loaded the bike and drove back home, once there I was able to check the electrics properly with a meter to find the 20amp fuse by the coil was open circuit and found that the 2nd fuse located here was a spare but also open circuit, I robbed the 15amp fuse out of my older KTM and then on pressing the starter she fired up straight way and many times after that. I have since ordered a 10 pack of 20Amp fuses (1.28+ VAT) from RS

Any thoughts I why it may have go in the 1st place

KTM 250 EXC-F six days 2015

Jmc

Check carefully for a chafing wire shorting to earth between the fuse and any loads served by that fuse.

If you remove the fuse and put a simple 12V buzzer / bulb in circuit you can wiggle away at the wires - when the buzzer sounds or bulb glows brightly you will have found your problem.

My nephew's '14 Husky 250 (same engine?) did much the same thing in the summer of '15.

Got to an enduro practice day - bike started straight away and warmed up nicely.
He got ready, prodded the starter and nothing - a few hundred yards of attempting a bump start and a long push back up the hill in high heat and back in the van.

Found that the fuel pump fuse had blown but already home by then (not used to FI bikes).
It's been ok since though.

No logical explanation.

Some time fuses just blow, just like a light bulb

I would agree with small fuses - and in this case it appears to be a main high current fuse, which unlike a light bulb shouldn't get hot..

Nobody wants a blown main fuse on a ride, particularly on a muddy lane - so I feel it is worth taking a few extra minutes to investigate reasons for a main fuse blow.

Had the same problem on my 16' FE 450. Main 20 amp fuse blown. Changed it and all was fine. Seems to happen when water gets in or near the electrics. Another issue could be that the battery terminals have come loose so maybe tighten the terminals. I now ride around with a dozen 20amp and 10 amp fuses

Cheers guys for all your responses, I will have a good look around the wiring loom to check for anything obvious, and just in case carry a pack of spares...!!

Jmc

Well I had a good look at the loom for the starter etc. but all was ok, I broke open the old fuses and although they looked ok when held up to the light once cut open the fuse element had a small split so obviously the fuse hadn't blown on a short circuit so I will assume that it just got tired over time.

I've fitted 2 new fuses (1 is a spare) and put the rest of the pack along with some other sizes in my trial tool roll. Bike started several times without hesitation.

Jmc

Similar issue on a Husky 450, turned out to be a short circuit in the aftermarket rear light, blew the fuse when the brake light came on.