Blown Fuse Starter

Having a shorting problem. When the starter button is pressed on my 91 ST1100 the starter engages momentarily, then immediately blows the 10 amp fuse.

The starter relay passed the test given in the manual, producing a strong click.

Sure could use some input, anyone have this problem, shed some light? How to proceed? Thank you.

D2, - disconnect the big starter cable and see if your fuse blows. If it stays intact, then it's a starter motor problem........

Roger. said:

D2, - disconnect the big starter cable and see if your fuse blows. If it stays intact, then it's a starter motor problem........

Click to expand...

Thank you, did this test, fuse stayed intact.

Look now at the starter and, or it's parts, which, what?

Fair warning, I have a 1300, and have not seen an 1100's wiring diagram. When you hit the starter button, you are activating the starter solenoid (big word for relay). That 10 amp fuse should be doing nothing more than protecting the coil winding in said solenoid; the starter is drawing 60 or 80 or 100 amps and does not use that fuse for anything. I'd look at the solenoid (maybe the 1100's have a separate starter relay?) because it is possible that it is shorting to ground and blowing the 10 amp fuse.

SMSW said:

(big word for relay)

Click to expand...

Also a word that differentiates it from a relay since they have electro-mechanics in common but aren't the same thing.

SMSW said:

Fair warning, I have a 1300, and have not seen an 1100's wiring diagram. When you hit the starter button, you are activating the starter solenoid (big word for relay). That 10 amp fuse should be doing nothing more than protecting the coil winding in said solenoid; the starter is drawing 60 or 80 or 100 amps and does not use that fuse for anything. I'd look at the solenoid (maybe the 1100's have a separate starter relay?) because it is possible that it is shorting to ground and blowing the 10 amp fuse.

Click to expand...

Had a look at the wiring diagram for my 91 ST1100. No solenoid shown there. The starter relay on the bike has passed the test described in the service manual.
So, the short is possibly between the fuse box and the starter relay? Is that reasonable? No, that can't be right, it passed the test described above by Roger. ***?

What else is on that fuse? I would think nothing. Power will go from the fuse to the starter switch, then to the starter relay. You could pull the wire off the starter relay, and hook it to an auto light bulb and then ground the other side of the bulb to the frame. Now when you hit the starter button, the light bulb will light and the fuse should not blow. But you said that disconnecting the heavy wire from the battery to the starter motor kept the fuse intact when you hit the button. This makes no sense unless the starter relay and something else in the starter are both on that 10 amp fuse.

That's right, nothing else on that fuse.

Ran the tests again; fuse intact until the starter wire connection is made at the relay.

Can this be anything other than a faulty relay?

Take a look at the red 4P connector at the starter relay just to the left of the main system fuse. Look for melted plastic. This is a common point of failure it the ST starting circuit.
If it looks bad, you'll need to perform the "red wire bypass".

Thanks Eagle, the 4p connector is not damaged.

To follow up, after searching the headlight area for obvious signs of a shorted wire that might cause the 10 amp ign. starter fuse to blow, and finding none, the starter switch and stop switch area was thoroughly cleaned a second time. This proved to be the cause, bike now starts fine and runs great. Thanks for all the suggestions. Dave