No spark at any of the plugs...

[hurleyman77]

I've got a '94 VMax that I've owned for almost a year, and it recently quit starting. It's been modded, but IDK how much. After some investigation, none of the plugs will spark when it turns over. After the first day that it quit, I got 1-2 sparks for every 10-15 engine turns, and now nothing at all.

It cranks real hard, especially since I've got it on a trickle charger all the time, but it just never fires. Interesting detail: when it was firing, it would backfire occasionally (but only when cranking or idling, I don't think it ever did while I was riding). I can imagine that if the previous owner modded the coils to fire every time, then if it misses on the compression stroke, it might fire on the following exhaust stroke that still has FAM left in it, thus backfiring, but IDK if that's actually what's going on.

The fact that I got 1-2 sparks before, and now nothing, leads me to suspect that it might have been a gradual onset rather than all of a sudden. If that's the case, then it would explain why it had been missing a little (before it just quit).

Since they've all quite, I'm almost positive it isn't the coils, but IDK what's between the coils and the battery. It really seems like there's not much.

Knowing these things, where do y'all suggest I look first?

Thanks in advance.

 

[Fire-medic]

Read the pick-up coil resistance between the two leads. This is the crank sensor coil not the ignition coil, the ignition coil is one of four, w/a spark plug lead attached.

If you don't get 81-121 ohms, your pick-up coil (senses the crank position) needs replacement. It tells the CDI what it needs to know about the pistons' locations in their cycles, to send an ignition pulse to the ignition coils to fire the spark plugs.

Wait 'till you find-out the price!

 

[MaxMidnight]

...that if the previous owner modded the coils to fire every time, then if it misses on the compression stroke, it might fire on the following exhaust stroke that still has FAM left in it, thus backfiring, but IDK if that's actually what's going on.

It does fire every stroke (as do many other bikes) so that won't be your issue. It is known as Wasted Spark

In addition to Mr Medics suggestion make sure that you have power going to the ignition unit , the Red/ White wire.

 

[sdt354]

Take a look at the wiring diagram on Sean's site. And check under- how to. http://www.morleysmuscle.com/ I don't think all the coils are bad. +1 to all the above.
Steve-o

 

[hurleyman77]

Ah, I didn't think the stock setup wasted a spark. Thanks. Still, if it misses on a compression stroke, and there's fuel left, and it fires on the exhaust stroke, wouldn't that backfire? Not real important, just curious.

Steve-O, so you mean that they might all stop firing even if only one coil is bad?

Thanks for all the suggestions, I'll definitely check them out.

 

[maxcruiser]

I've got a '94 VMax that I've owned for almost a year, and it recently quit starting. It's been modded, but IDK how much. After some investigation, none of the plugs will spark when it turns over. After the first day that it quit, I got 1-2 sparks for every 10-15 engine turns, and now nothing at all.

It cranks real hard, especially since I've got it on a trickle charger all the time, but it just never fires. Interesting detail: when it was firing, it would backfire occasionally (but only when cranking or idling, I don't think it ever did while I was riding). I can imagine that if the previous owner modded the coils to fire every time, then if it misses on the compression stroke, it might fire on the following exhaust stroke that still has FAM left in it, thus backfiring, but IDK if that's actually what's going on.

The fact that I got 1-2 sparks before, and now nothing, leads me to suspect that it might have been a gradual onset rather than all of a sudden. If that's the case, then it would explain why it had been missing a little (before it just quit).

Since they've all quite, I'm almost positive it isn't the coils, but IDK what's between the coils and the battery. It really seems like there's not much.

Knowing these things, where do y'all suggest I look first?

Thanks in advance.

Have you checked or tried bypassing the side stand switch? Easy enough to do in your process of elimination.

Also check the electrical plugs for corrosion that are clumped together with the side stand switch, under the left side cover (under the seat).

Mike

 

[MaxMidnight]

Ah, I didn't think the stock setup wasted a spark. Thanks. Still, if it misses on a compression stroke, and there's fuel left, and it fires on the exhaust stroke, wouldn't that backfire? Not real important, just curious.

Yes that would be a reasonable situation. However I think it would be unlikely (impossible?) that you could only get a spark on the exhaust stroke.

...so you mean that they might all stop firing even if only one coil is bad?

If the pick-up coil was duff (and there is only one on a '94 bike) then you would not get a spark (re Mr Medics suggested check).
If the resistance checks out OK then you will need to start checking components in a logical way. That is why I suggested that you establish that you have power to the ignition unit as a starting point.
Depending on the outcome will direct where to check next.

If an ignition coil wasn't working (for whatever reason) I would expect the motor to run, albeit with a noticeable misfire.

 

[hurleyman77]

Maxcruiser, do you mean that the stand switch (or one of the plugs near there) might be grounding out or not connected? It seems like if the switch were bad it wouldn't turn over at all. I'll check and see...

MaxMidnight, Ah, the pickup coil, I thought you were suggesting that a bad ignition coil might make the others also stop firing. The pickup coil makes more sense. As for the backfire, my thought was that if I was getting an inconsistent spark, then it might be possible every once in a while to miss a compression stroke and then start firing again. Since I know it's been backfiring, and I know that it's been missing, AND I know that the ignition system is doing something screwy, that seems like the most likely scenario ;-)

Before I found out that it fires every stroke, I was really kinda worried about the occasional backfire because the only way that can happen (that I know of) in a regular system is with a really serious problem!

Thanks fellas, I'll check that out.

 

[sdt354]

Ah, I didn't think the stock setup wasted a spark. Thanks. Still, if it misses on a compression stroke, and there's fuel left, and it fires on the exhaust stroke, wouldn't that backfire? Not real important, just curious.

Steve-O, so you mean that they might all stop firing even if only one coil is bad?

Thanks for all the suggestions, I'll definitely check them out.

No, the ones that are good will fire as long as they get juice, and get grounded by the cdi. The cdi needs the signal from the ignition pick-up to do this.
First, since none fire, I'd check for voltage at one side of the coil plugs, key on.
A test light or volt meter will do it. If no voltage, check the ignition fuse.

 

[MaxMidnight]

Another quick check would be to take off the connectors to the ignition unit and check for water ingress/ corrosion within the multi-blocks.

 

[dingy]

Maxcruiser, do you mean that the stand switch (or one of the plugs near there) might be grounding out or not connected? It seems like if the switch were bad it wouldn't turn over at all. I'll check and see...

MaxMidnight, Ah, the pickup coil, I thought you were suggesting that a bad ignition coil might make the others also stop firing. The pickup coil makes more sense. As for the backfire, my thought was that if I was getting an inconsistent spark, then it might be possible every once in a while to miss a compression stroke and then start firing again. Since I know it's been backfiring, and I know that it's been missing, AND I know that the ignition system is doing something screwy, that seems like the most likely scenario ;-)

Before I found out that it fires every stroke, I was really kinda worried about the occasional backfire because the only way that can happen (that I know of) in a regular system is with a really serious problem!

Thanks fellas, I'll check that out.

Any easy check for the side stand is either unplug the side stand relay, it is the only one with a blue base on it, or unplug the connector to the stand and jumper the two wires together on the harness side connector.

This will bypass part of the safety systems that prevent motor from cranking in gear with side stand down.

Also check the engine stop switch on right handle bar control, a failure (open) will not power the coils or the TCI.

Gary

 

[hurleyman77]

Alright, dumb question: where do I get to the pickup coil to check it? I've tried to do my due diligence, but all I can find out is what it looks like (the part on the crank shaft), but not where it plugs in.

Also, what does the CDI look like?

I bypassed the stand switch by unplugging it and jumping the wires, but nothing changed. It still cranks hard, but won't fire. I also used my ohmmeter to check the switch itself and it alternates between infinite and near-zero when I press and release it, so it seems to be working.

In other research, I think I also discovered that I don't have VBoost on this bike. I initially suspected that something was different when my bike didn't make the servo noises that other VMAXes make when you turn the key on. It's a 2WE (not Japanese, right?) so it seems strange that it wouldn't have the VBoost installed. At any rate, there are boots between the carbs at the intake manifold, but it doesn't look like there could be valves inside those boots, nor are there controls for VBoost in the middle of the carbs.

Is that a thing that is done, VMAX without VBoost? Is it worth trying to install it myself?

Again, thanks for the help, guys.

 

[CaptainKyle]

Alright, dumb question: where do I get to the pickup coil to check it? I've tried to do my due diligence, but all I can find out is what it looks like (the part on the crank shaft), but not where it plugs in.

Also, what does the CDI look like?

I bypassed the stand switch by unplugging it and jumping the wires, but nothing changed. It still cranks hard, but won't fire. I also used my ohmmeter to check the switch itself and it alternates between infinite and near-zero when I press and release it, so it seems to be working.

In other research, I think I also discovered that I don't have VBoost on this bike. I initially suspected that something was different when my bike didn't make the servo noises that other VMAXes make when you turn the key on. It's a 2WE (not Japanese, right?) so it seems strange that it wouldn't have the VBoost installed. At any rate, there are boots between the carbs at the intake manifold, but it doesn't look like there could be valves inside those boots, nor are there controls for VBoost in the middle of the carbs.

Is that a thing that is done, VMAX without VBoost? Is it worth trying to install it myself?

Again, thanks for the help, guys.

Remove your left side cover & the pickup coil wires run up behind it under the seat . It will be a 2 wire connector orange & black. The CDI is mounted under the faux cover in front of the air box & its the big black square box . It plugs in from the right side . If you want the Vboost back its not to hard to install but the controllers are not super cheap.

 

[hurleyman77]

Awesome! Thanks!

 

[hurleyman77]

So I checked the end that looked like it was going down to the crank case and it read infinite resistance, no connection at all. I read the other side and got 220 or so, so either way it looks like I need a new pickup coil.

They look something like #1 in this pic, right? AKA stator? http://pdn1.vnexttech.com/yam/mcy/1994/vmx12f_fc/generator/assembly_files/10/0_1.png

 

[hurleyman77]

Sorry, that link didn't work. This is what I'm thinking is also called a pickup coil.
http://www.ebay.com/itm/Yamaha-2002..._Accessories_Gear&hash=item2ec8dcac4d&vxp=mtr

 

[MaxMidnight]

So I checked the end that looked like it was going down to the crank case and it read infinite resistance, no connection at all. I read the other side and got 220 or so, so either way it looks like I need a new pickup coil.

Not sure what you have checked there but it doesn't sound like the pick-up coil.
The test is to measure the resistance between the orange and black wires which should be between 81 and 121 ohms.

The picture you have shown is that of the alternator stator NOT the pick-up coil.
It is #3 in the illustration here and this is a photo of one.

That you are trying to fix this yourself is commendable and asking questions is a good way to learn.
However, it does seem to me that you are attempting a repair without a workshop manual?
The Yameringha Service Manual is available on line here and Haynes or Clymer manuals are available at a reasonable prince.

They are a good investment and will mean that you will be able to proceed with your diagnosis without having to wait for a response to your posting.

 

[marsmax85]

plus one on the manuals saves time and money !!!

 

[hurleyman77]

Yeah, I found a black and orange pair under the seat, but I couldn't tell which side went to the pickup and which side went on to the ignition, so I checked both sides. One side was open and the other side was 220 Ohms.

Yeah, that was going to be my next step. I don't plan on doing a lot to this bike, so I was hoping I could just get it fixed and move on, but it sounds like a manual is going to be more important than usual.

 

[CaptainKyle]

I have seen the pick up coil wires break in the rubber grommet going into the cover more than once so you might want to check that to.