Blowing Main Fuse

[Anonymous]

Ah, what a great week. Got the bike back on the road Tuesday, got 30 miles away and broke the clutch cable on the highway! Got the bike to a YAMAHA dealer, and had them fix the dang thing (since I don't have a truck or a trailer)

Rode it home Friday and got the parts for my Front Master Cylinder rebuild on Friday night. Saturday - rebuilt the FMC and everything was fine.

Went out this morning and DEAD BIKE! The 15 Amp main fuse was blown, and when I tried to stick a new on in there, the new one blew!

Nothing obvious is causing the short, what is the next step? The ignition switch? Or is there a more likely culprit? (It is not the positive battey leads or wires)

Thanks, everyone has been great with helping me get this 1983 GS750ES onto the road and safe!

Jay

[focus frenzy]

Ok the main power wire from the fuse box goes two places, the regulator/rectifier, and the ignition switch.
disconect the red wire going to the regulator/ rectifier and see if it still blows fuses, fuse holds you have a short in the reg/rect or bad diodes in it.

if it still blows fuses unplug the switch and retry,holds= bad switch, blows=short in harness, inspect harness for chafed wires, also remove the fuse block and check for a short between it and the battery holder it is mounted too.

[Billy Ricks]

Is the fuse blowing after you get the bike started? Years ago I had a problem with mine blowing after running a few seconds. Turned out to be the dreaded stator problem. It might be time for you to test the regulator/rectifier and the stator.

[SqDancerLynn1]

with the recient work done to your bike, i would check the starter saftey sw by the clutch lever and check the front brake sw by the master cyl

[Anonymous]

The run (kill) switch was disabled with the bike. Turning the key on gives no lights to the gauges.

Concerning the reg/rec :

By pulling the red wire, are you meaning the red wire on the front (that is in a clip with the other 4 wires?) and pulling the entire clip? Also, there is a single wire coming off the right side of the reg/rec (which is red) and goes to the negative terminal on the battery. Is this right? (I assume the wire is red becuase it has been replaced)

Taking off the clip - the main fuse does not blow.

Did a parts search and found a reg/rec for like $500.00?!?! Does this sound right? Are used ones worth purchasing?

Thanks!
Jay - The Inexperienced Newguy

[argonsagas]

[quote="thoox"]The run (kill) switch was disabled with the bike. Turning the key on gives no lights to the gauges.

Concerning the reg/rec :

By pulling the red wire, are you meaning the red wire on the front (that is in a clip with the other 4 wires?) and pulling the entire clip? Also, there is a single wire coming off the right side of the reg/rec (which is red) and goes to the negative terminal on the battery. Is this right? (I assume the wire is red becuase it has been replaced)

Taking off the clip - the main fuse does not blow.



As Focus Frenzy said, if the wire is isolated from the batter and your fuse holds, then there is a problem with the R/R.

See highlighted part of your post above. Looks like you have the red wire going to the wrong post on the battery. This is guaranteed to blow fuses, and, unfortunately, the R/R as also likely to go.

Check your wiring connections. If you are not certain on wire colors because of earlier changes, then there are probably a variety of splices in your system, which may contribute problems of their own. It is usually best to replace them and be sure.

If several wires are the same colour, and their connections are clean and solid, then you can identify them easily by isolating each and then marking them. A simple trick I use is nail polish.
I bought some from a jobber/junk-store, in different colours, for 50 cents a bottle.

Good luck.


If you need a new one then that's what you need....a NEW one. The site sponsor, Electrex, makes a very good unit, and they give a two year guarantee on it as well. I don't know the current price, but it will certainly be much less than $500.

[Anonymous]

In case anyone else has input let me clarify the two red wires.

After closer inspection, the previous owner of the bike has the black/white ground wire replaced with a red wire and going to the neg. side of the battery and the bolt ground on the reg/rec.

If I remove the clip (1 red, 4 yellow, 1 b/w (now red)) from the reg/rec, I can put in a fuse. I reconnected the reg/rec and everything was fine. So I started the bike and starting going through the Stator Papers checklist and tests.

Right before I got to the stator tests, the fuse started blowing again.

So, I guess I will be replacing the reg/rec with an Electrex unit! And then will check the stator as soon as it is installed.

Thanks,
Jay

[SqDancerLynn1]

You can check the stator while you are waiting for the reg. disconnect stator wires & hook up AC volt meter and run motor 5K rpm between any of the stator wire pairs you should read Minimum 75-80 vac

[argonsagas]

You can check the stator while you are waiting for the reg. disconnect stator wires & hook up AC volt meter and run motor 5K rpm between any of the stator wire pairs you should read Minimum 75-80 vac

Right you are. (as usual)

Next best advice: Print the Stator Papers and take them with you to the bike, along with a digital volt-ohm meter.