Need electrical problem help please!

[fatbiker]

My newly refurbished clutch master cylinder and Morley Muscle seat came in this last week and I finally was able to take the bike out after a month of sitting in the garage. Great work on the m/c by Sean and his Muscle seat is the best Vmax upgrade of all time!

Got the bike out on the road and ran her at wide open throttle. Felt like she was running on three cylinders and the Vboost was missing. Took her home and blew some carb cleaner down the carbs, checked for spark on all 4 plugs and they were fine. While in neutral I would turn the throttle wide open and it would bog down at 4k and sometimes lower around 2 or 3K. Tried reseating the carbs into the boots (another problem altogether, see post in Carb forum), and all of a sudden the bike ran great. Took her out on the freeway and when I tried to use the turn signals they didn't work. Next thing I know the tach and temp gauges aren't working. All the lights were on including temp, tach, headlight, turn signals and brakes. All of a sudden the throttle isn't responding. If I try to give her gas the engine bogs down and tries to die. It idled fine for a few minutes then eventually died and wouldn't start up. I checked the fuses and two were blown; the signaling system fuse and the ignition fuse. Replaced both .After about 10 minutes of letting her cool down she starts up and runs great except I still don't have working turn signals or tach/temp gauges. After 5 minutes the process started over again. No throttle then eventually dies. Checked fuses again but this time none are blown. I went thru this routine three times before getting her home. I assume there is an electrical problem going on somewhere. Any ideas where to start?

Fatbiker

 

[wood1]

What is your battery voltage key off, at idle and at 2500+ rpm? Someone that was pointed out to me a couple days ago.

 

[davesax36]

Check the brown wire that leads from the ignition switch to the main fuse block.

(HA HA I BEAT MILES!!!!)

It's possible that there is something going on in there that will cut the power to pretty much everything. You may also have a hot start problem. Wood is right, though. It sounds like you may have a charging voltage problem.

 

[fatbiker]

Took a look at the bike this morning. The fan fuse and the signal fuse were blown. Not the ignition fuse as I first thought. The bike started up just fine and responded to the throttle. Was able to rev her up all the way to redline without any problems. I checked for any loose or grounded wires near the battery but didn't see any. I will remove the airbox and rear seat to check every wire possible. As before the tach/temp gauges do not work nor do the turn signals. Also the horn still doesn't work. It's pretty obvious that the system isn't charging

Voltage:

Battery - 11.54
Idle - 11.90
2500 - 12.40
After running the bike for 5 minutes and turning her off - 11.31

The 2500 idle is just a guess as the tach wasn't working.

Fatbiker

 

[Miles Long]

Check the brown wire that leads from the ignition switch to the main fuse block.

(HA HA I BEAT MILES!!!!)

It's possible that there is something going on in there that will cut the power to pretty much everything. You may also have a hot start problem. Wood is right, though. It sounds like you may have a charging voltage problem.

Curse you, Dave!

I agree - gotta be electrical, the blown ignition fuse will stop you dead. If that and other fuses are failing, there must be an overload, or a short circuit.
Begin by checking out the source of the power to the fuse box - yes that brown wire. But also everything before the brown wire, right back to the positive side of the battery. Especially on older bikes like yours, there are a few spots prone to failure.
Dave will fill you in on the details:clapping:
Cheers!

 

[fatbiker]

I decided to start at the last place where I did electrical work which is the rear turn signals and brake light. I installed a LED brake light while waiting on my parts and used a copy of the electrical diagram to make sure everything went back together. I guess I've done a bad job. I've disconnected the LED light wires and now the turn signals, tach, and temp gauge work but the turn signals are all messed up.

If I turn on the right signal the front and rear right side signals flash as they should.

If I turn on the left signal both front signals and the headlight flash along with the rear brake light. The rear signals do not come on at all.

Checked voltage at the battery and got the same results as before. I plan to let her run at idle for a long while and see if the battery is draining.

Will check the brown wire along with all wires I can find. I did replace the wiring harness with a newer one a couple of months ago and it ran fine with no problems. This was before I installed the LED brake light.

Thanks for all the fast replies! I really appreciate them!

Fatbiker

 

[fatbiker]

Update:

I let the bike idle for awhile and after 5 minutes I heard a main 30 amp fuse blow and the bike died. Only one of the two fuses blew. Thinking that my rear brake light and turn signals are wired wrong I disconnected all of them. I replaced the fuse and let the bike idle awhile more. As I was disconnecting the right air scoop the bike died suddenly and I noticed a lot of smoke coming from the ground wire that goes to the water housing. I've included a picture. Both the main 30 amp fuses did not blow. I traced the ground wire thru the wiring harness and it looks like it goes back towards the battery. It is burn to a crisp and I can see where it burnt thru the electrical tape that goes around harness. My guess is that it's burnt completely from start to finish.

I am not sure where this ground wire ends up or what could be causing it to burn to a crisp. I am assuming it goes to the fan as that fuse has blown two times as well as the signal fuse. Any ideas??

Fatbiker

 

[Miles Long]

There is only one 30 amp main fuse. The other one is a spare.
A blown main fuse is a major concern, indicating a short circuit before power is reaching the fuse box.
I would first check the battery itself - it may have an internal short. This would also account for the poor voltage readings. Then of course the main ground wire has to be secure on post and frame, and the positive wiring and components(solenoid, fuse, etc.) must not have any continuity to ground. Easy to check with a meter.
Electrical problems can be frustrating. Troubleshooting has to be done on a systematic basis, one thing at a time, starting at the source.
Good luck!

 

[fatbiker]

So far I've traced the ground wire back to where it connects with two other ground wires. From there they go back towards the battery. Best guess is that this ground goes back to the rear turn signals. Could connecting the rear turn signals wrong cause all this? Would low charging be related as well?

Fatbiker

 

[davesax36]

I don't know if this will help, but http://www.morleysmuscle.com/wp-content/uploads/2009/12/Vmax-Wiring_Diagrams1.pdf

 

[fatbiker]

Thanks davesax, I have the same diagram and am using it to trace things back.

New development. I disconnected all the wires to the rear turn signals and brake lights then started the engine. It idles fine so I started touching each and every wire to see if there was a short somewhere. When I touched the wires coming from the regulator rectifier they were hot as a pistol an were beginning to smoke! Turned off the power real fast before anything blew up. So now the R/R and alternator are in question. If one or both of these go bad will it cause an overload in the system? Enough to blow fuses and burn ground wire? If one of these is bad it explains why I'm not getting a good charge to the battery. The R/R looks to be original, it's made from Sun Co. out of Japan.

Fatbiker

 

[Miles Long]

Oh Yeah!
If you look at the schematic, you will see that the main + wire from the main fuse goes thru the "crimp" connection, then to the ignition switch and the feed from the RR. If this wire were to go to ground (failed diodes in the RR?), it would certainly pop the main fuse.
You should check your entire charging system, using the Electrosport fault-finding chart. There is a link to it within RaWarrior's excellent thread in the "How-to" stickies.
The original RR's were only grounded thru the mounting location. You may want to start by cleaning this. Also, you might find the three-wire connection from the stator to the RR is corroded, or burnt thru completely. All the details are covered in Ra's thread.
Cheers!

 

[fatbiker]

I replaced the burnt negative wire that went to the water thermostat housing. I also bypassed the R/R crimp and ran it directly to the battery. Also removed the plastic connector that connects the R/R to the alternator/stator (??) and did a direct wire job. Started the bike and the R/R got hot real fast. Is that normal?

Also checked the charging again:

Original reading:

Not running - 11.54
Idle - 11.90
2500 - 12.40
After running the bike for 5 minutes and turning her off - 11.31

New reading -

Not running - 12.54
Idle - 13.25
2500 rpm - 13.85

It's an improvement but not as good as I had hoped.

 

[Traumahawk]

Now I know that the R/R gets hot, because it shunts excess voltage as heat.

13.25 volts at idle is actually pretty good. Not great....but pretty good.

 

[fatbiker]

Took her out for a spin and the original problem still exists. Idles good but when I twist the throttle and the rpm's reach 3 or 4K on up it feels like I'm running on 3 cylinders. I can feel a miss but it's not a timed miss. Before I took her on the road I sync'd the carbs and checked the voltage. Voltage is better than ever and the sync appeared ok after some minor adjustments. No fuses were blown this time but I didn't take her far.

Can the R/R still be bad and causing this? I'm at a complete loss now.

Fatbiker

 

[Traumahawk]

I wonder now if its a bad pick up coil? I know somewhere in the manual there is a way to test it.

 

[wood1]

Pre '93 bikes have two, the resistance value is the test for a pick up coil

 

[wood1]

Five pin connector under the seat, left side of the bike?

 

[fatbiker]

How do I test the pickup coils? I've read the How To guide on the forums but I'm a complete noob when using a multi-meter. Also read the service manual and it says to each wire with the Orange wire. Shouldn't you test each wire against the Black ground wire? I had the multimeter set for 20K ohms and from Black to each wire I got a reading of 119 plus or minus 2. Am I doing this correctly?

Fatbiker

 

[wood1]

Plug is just above the tank on the left side, disconnect it and check the resistance between the black wire and the others. 1985-1992 resistance should be 95-121.2 at 68F