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Discussion Starter · #1 ·
So I've ran in to some starting issue.. 94 VT600C. I havnt had a chance to go buy a manual yet but have found one that I downloaded for the 97/98.. It seems mostly very similar. This week It went from running erratically, sputtering dieing a couple times to yesterday morning not firing off at all.
Spark check showed that the back cylinder isn't firing.

I dont have a peak voltage meter, but reading around I found some reference figures to ohm out the coils.. front coil primarys ohm out to 2.5-2.6 and across the secondarys at the end of the plug wires, 30-34k-ish. Back coil the primarys ohmd out to .5 ohms, and about the same as the front on the secondarys. At one point in my fiddling around, I observed the back cylinder sparking and i ohmd the primaries on the back coil to 2.5 then, but it ceased shortly after and back to about a half. So I deduct that one's bad by that.

I've suspected the rear one isn't firing all the time this past week. What's different now is the fuel seems to have stopped being delivered. after attempting to start 8 or 10 seconds of cranking, swiftly pulling a front plug came out dry. The pump wasn't coming on either. The shop manual I dl'd diagrams look like mine, the diagnosis seemed to be on as well. What I don't understand in the diagnosis steps, it says to unplug the fuel cut off relay to check the plugin harness. It says to check continuity between the black/blue wire and ground and if there is continuity, then the relay is bad. I'm not sure how this can be deduced when the relay is not plugged in to the harness at that time.

Also, the third wire on the relay plug, the yellow one I believe it is.... I assume this is what energizes the relay to send current through the relay on to the fuel pump. What's on the other end of that wire to tell the pump to kick in? Is there a grounding switch on the carb float to tell it to send fuel on when the bowl is empty?

I was telling a bike owner friend of my woes, and he chuckled 'welcome to biking!' I was at least hoping for a solid month of 2 wheel joy before having to deal with the issues.
 

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the black wire to your FP relay should have battery voltage with the key on.
the black and blue is the hot wire to the FP after the relay is energized.
The yellow and blue is the ground for the relay , and also controls the ground for the rear coils primary circuit.

to answer your question, the ignition modual grounds that yellow wire, fuel pump relay and rear coil at the same time.

you could swap coils from front to rear to confirm that the coil has failed.
make sure you have power at the coils black and white wire.

You may have blown a 10 amp fuse in the fuse box, please check them all.

http://www.hondashadow.net/forum/53-general-discussion/105085-honda-service-manual-vlx-vt600.html
link for the factory manual
 

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Discussion Starter · #3 ·

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So I was digging around a bit and I found this in this thread below...

http://www.hondashadow.net/forum/72-technical-discussion/93163-fuel-cut-off-relay.html

Shadow83 says:
Is that pretty much saying, if the rear coil does not function to provide a spark, the fuel pump wont run?
If the primary circuit in the coil goes open, then it should operate the fP normaly, but if its shorted it may cause problems with the ground to the FP relay.
you can disconnect the coils ground and see if the pump runs.
 

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Discussion Starter · #5 ·
Well so Friday morning she fired right up and I rode to work. Mostly at stop lights on one cylinder, when I'd take off the other one would kick in. Off and on all day Friday, during slow times at the shop I'd go start it up and I had a timing light on each of the plug wires, saw the occasional stumble but both cylinders fired all the day.

Fast-forward to after work ,I went to go somewhere, and a mile from home she shut down on me. All firing has ceased. Pull plug wire no spark. Had to walk er back home.

So today I had a full day to run some tests.. found some schematics for a DIY peak voltage adapter and made one to follow through the service manual tests. Pulse generator peaked out above minimum but both coils were like 8-10v peak where it calls for 100V minimum. Pulled the ICM to check the connections for corrosion, which there was none.. Good ground, all plugs on the bike are good. :/ All signs point to the ICM. Sucks. Be a couple weeks before I can even have enough money to order one, and hopefully the one I need is still on Ebay. Because it's the only one on the entire internet I could find. And local sources probably will be wanting like 300 bucks for one betcha a dollar.
 

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Well so Friday morning she fired right up and I rode to work. Mostly at stop lights on one cylinder, when I'd take off the other one would kick in. Off and on all day Friday, during slow times at the shop I'd go start it up and I had a timing light on each of the plug wires, saw the occasional stumble but both cylinders fired all the day.

Fast-forward to after work ,I went to go somewhere, and a mile from home she shut down on me. All firing has ceased. Pull plug wire no spark. Had to walk er back home.

So today I had a full day to run some tests.. found some schematics for a DIY peak voltage adapter and made one to follow through the service manual tests. Pulse generator peaked out above minimum but both coils were like 8-10v peak where it calls for 100V minimum. Pulled the ICM to check the connections for corrosion, which there was none.. Good ground, all plugs on the bike are good. :/ All signs point to the ICM. Sucks. Be a couple weeks before I can even have enough money to order one, and hopefully the one I need is still on Ebay. Because it's the only one on the entire internet I could find. And local sources probably will be wanting like 300 bucks for one betcha a dollar.
Can you share this home made peak voltage tester? thanks
 

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Discussion Starter · #7 ·
Surely, I found it here

In the comments is the schematic...
http://i1232.photobucket.com/albums/ff374/mikeyb3649/DVA.png

works rather nicely. I had a problem finding a 400volt DC 22uf capacitor the largest they had at radio shack was 35 volt 22uf, so i grabbed 4 of them and soldered them together as a parallel bundle (capacitors add together that way), so it would work up to 140 volts to cover the coil packs peak minimum of 100. Donno what would happen if it got higher.. Figured if it blew the thing then I'm good and the 10 or 12 bucks to make the thing was worth it ;)
 

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ok, I've seen that one, nice. dont know if they would work properly in par like that,
but was gonna ask if you found a cap rated that high.
when batteries are set up in par circuit the voltage is still only 12.6 higher avail corrent, but iwhen in series its goes up to 25volt. something to consider.
 

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Discussion Starter · #9 ·
I read that capacitors in parallel cTotal = c1 + c2 + c3 etc... Tho I didn't consider the uF add together as well. I dont know enough about electricity details to know what difference the uF rating makes. I located some 400vDC capacitors on ebay I ordered. I've been looking at misc junk electronics around the house for one I can steal off a board but no luck yet =).

Even still, the coils give ohms where they should be that I've seen aorund on other references.. ~2.5 on primary, ~30k on secondary.. Refrigerated cold and heated in the oven it goes up a hair but that's to be expected. And the pulse generator's wires look newer compared to other wires in the bundles up near the steering knuckle. Really only leaves one thing else eh? o_O
 

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Have you load tested the battery? What is the charging voltage at idle and at 2K? Due to the weakness of the charging sys, a weak battery can draw enough juice to starve the ignition. Check for heat damage to the charging wires.
 
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