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Louie
Louie, Technician
Category: Motorcycle
Satisfied Customers: 11619
Experience:  25+ yrs. experience
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I have a 2002 Yamaha v star classic 1100 and it cranks but

Customer Question

I have a 2002 Yamaha v star classic 1100 and it cranks but no start. There is fuel to the carbs and new spark plugs with what looks like good spark.
It ran great until the rectifier overheated, melted and was a small fire below the battery box. I have replaced the stator/pickup coil, rectifier and main wiring harness. I don't know what else to check. Any help would be appreciated.
Submitted: 9 days ago.
Category: Motorcycle
Expert:  Louie replied 9 days ago.

Hi and welcome to the site, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.

Initially, let's try and review the basics. Proposed preliminary checks (if have not been done):

  • • drain-clean tank / fuel path and replace with fresh fuel (even if just to eliminate as a suspect);
  • • attempt to start again working the throttle as if trying to flood the engine;
  • • then remove the spark plugs:
  • - determine if the tips got wet with fuel;
  • - carefully perform a spark test.
  • • pour a small amount of raw fuel to the spark plug hole;
  • • install the spark plugs and attempt to start again;
  • • if still a no-go, drain the carb bowls individually to compare quality and quantity of contents.
Customer: replied 9 days ago.
Hi Louie,
I should give some history on the bike. I have done everything you have listed when I first got the bike. Front & rear brakes, I removed the tank and fenders to paint and do body work at which time I had drained what was left in the tank, replaced the fuel filter & cleaned the carb before putting fresh fuel in before taking it on it's first trip as the new owner - it ran great. When I pull in the driveway after 30 minutes or so the bottom half of the battery box is melted along with most of the connectors because of the rectifier overheating.
I've torn everything apart and found a used wiring harness to replace instead of splicing wires to the burnt ones. I found that the starter solenoid was not original so I had to replace that along with the battery, rectifier, stator/pickup coil (it is one unit), and ignition coils. I've checked them all with a meter and they are within the specs in the manual.
It cranks fine but will not run.
Since then I have replaced the spark plugs, checked that the fuel pump is operating by removing the gas line from each carb and switching the key on briefly and fuel does pump through.
I've checked spark at each cylinder and it appears fine.
I've sprayed a little starting fluid into the intake and when I crank it I get a loud pop from the #1 cylinder. That appears to have been caused from loose bolts on the exhaust manifold. I tightened them down and checked #2 as well. I've had both pipes off for the oil change but did not change the gaskets.
The only thing I could think of was the pickups being reversed - #1 firing the #2 on the exhaust but the stator/pickup is OEM.
Expert:  Louie replied 8 days ago.

Appreciate the information and on what has been tried.

Further with the basics / as a process of elimination. Proposed secondary checks (again if have not been done):

  • • re-inspect the battery, its ground lines and/or re-check and re-clean the battery cables + terminals, connectors and wiring;
  • • consider hard wiring a secondary ground line from the battery's - terminal to the harness' black wires; and
  • • to the engine; and
  • • also to the frame.
Customer: replied 8 days ago.
Tonight I tested the ground(black) wire from the ecu to the battery neg post and I am getting .4 ohm. Battery connections look good but I added a small jumper wire from the neg post to the frame but still doesn't start. I will try and solder in some extra grounds as you suggested.
I did find a 4 wire connector that was laying behind the battery box that I missed and I have no idea where it goes. All the plugs were accounted for on the harness except this one. I've attached pictures and the rectifier is in the background and it is connected.
I don't see the 4 wires in the manual- yellow/brown, lightblue, brown/blk and black with a 4 pin connector , even for the California version.
Thanks
Expert:  Louie replied 8 days ago.

Sorry, mobile with sluggish Internet if at all.

Would run a sear for this connector soon as I get back to my regular workstation but may not be immediate.

Or perhaps you can post back with LINKs to pdf/electronic copies of both Service Manuals.

Incidentally, have you attempted to do a start with the side stand folded up?

Customer: replied 8 days ago.
I did try to start with the stand up but still cranks good - no start.Here are a couple links:
Electrical diagrams (mine is the CA version with the solenoid valve): https://sites.google.com/site/vstar1100kb/home/5-modifications/electronics
Someone else who doesn't know what this connector is: http://www.vstarforum.com/Identify-this-connector-ThreadThe Chiltons says there is no way to diagnose the ECU/Ignition module. Can a shop diagnose that? I hate to throw more parts at it and I don't think the ECU was close enough to the heat to cause a problem and I hear they rarely fail.
Expert:  Louie replied 7 days ago.

Appreciate the links to the wiring diagrams and on your patience.

And yes, field/shop test would be by process of elimination. If all other factors checks good and yet no spark, then the Ignitor unit is deemed faulty if not highly suspect. The only sure way is to try and to (temporarily) replace with a known to be good Ignitor unit.

First, is there pulsating low voltage from the pickup coil when attempting to start? ...between the gray and black/blue wires?

Is there IGN+12V on the red/black wires to the ignition coils and the Ignitor unit?

How about on the red/blue wire to the Ignitor unit? ...on the blue/black wire?

Customer: replied 7 days ago.
I will check the volts on those wires a soon as I can. I do have spark at the plugs and if the ecu were bad would there be spark at all? Or could a bad ecu also
cause the timing of the spark to be off?
Thanks
Expert:  Louie replied 7 days ago.

The timing is dictated by the low pulsating voltage from the pickup coil. The pickup coil is fixed mounted. There are small/narrow metal tab(s) attached to the rotor that passes the face of the pickup coil. This action induces the low pulsating voltage. Since the stator/pickup coil is OEM and the rotor is presumably still the same, then the spark/timing could not have change / be off.

A bad ECU would be no spark at all.

On the otherhand, a low (or missing) IGN+12V on the red/black wires and/or on the red/blue wire to the Ignitor unit could cause weak/poor or no spark.

Customer: replied 5 days ago.
I did some testing from your instructions and this is what I found:
1) There is AC voltage from both the gray and black wires from the PU coil as I tested them individually.
2) Into the ignitor unit:
red/blu wire = 12v DC with key on.
blu/blk wire = 5v DC with key on
3) Feed into right side ignition coil:
blk wire = 8v DC with key on for 5 seconds then I hear a click and 0 volts.
red wire = 12v DC with key on continuous
4) Feed into left side ignition coil:
orange wire = 7v DC for 5 seconds then 'click' and drops to almost 0 volts (.045...)
red wire = 9.8 volts with key on continuous.I'm not sure if this indicates any issues. I mentioned I did see spark at both cylinders when I originally started looking into the problem so it seems like it would have to be weak spark? Could weak spark on only one cylinder cause it not to start?thanks
Expert:  Louie replied 4 days ago.

Hi again.

On:

  • ignitor unit red/blu wire = 12v DC with key on.....presence good....consistency? - please test again while attempting to start/engine cranking;
  • right side ignition coil / red wire = 12v DC with key on continuous.....presence good....consistency? - please test again while attempting to start/engine cranking;
  • left side ignition coil / red wire = 9.8 volts.....same please.

The "...left side ignition coil / red wire = 9.8 volts..." is concerning as I was expecting for it to be likewise 12V. Can you please re-check / trace this particular red wire?

Or better yet, temporarily hardwire both ignition coil's red wire terminal directly to the battery's + terminal for test purposes. Do not remove/disconnect the existing red wire.