[Mayapaso]

Up to now, I've been taking the ST round the block for short 10 minute test rides as I progressively go through everything electrical on this bike. Had a first proper test ride today, but after 20 minutes the bike suddenly died as I revved it to to 8000rpm for the first time. It would then turn over but not fire up. Got it home. Battery was now run down from trying to start it and showed 12.8v across the terminals but only 6.8v with the ignition on, so it was a dead bike. Turned out the 5 amp fuse in the group of 3 fuses under the seat had blown, but noticed the relay next to it was hot. Swapped it for a new spare, replaced the fuse, the new relay runs cold, so issue hopefully solved.

However, the owners manual shows the blown fuse as 5 amp, but the wiring schematic from this forum shows 7.5amp. Which is the correct fuse? EDIT: I marked the wrong relay; it's the other that's running hot.

 

[Mayapaso]

Sorry, can never seem to sort out the photos. I uploaded the 3 photos, clicked on thumbnail for all 3, and it ends up in this mess.

 

[Turbomart]

From the ST4 repair manual it says 7.5A fuse. If I remember rightly the owners manual is from a different year model so I would go with the repair manual.

 

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Parts fiche for '00 ST4 shows only two amperages for those fuses; 7.5 and 20.

FWIW, I had the same issue with my '99 ST2. It would randomly die while riding. Would start up again after a few tries. As it became less intermittent, I was able to trace it back to that same relay. I replaced both, assuming the second wouldn't be too far behind in failing.