Dying while driving

[Jack01]

Hi all. Curious if anyone has any insights about the following issue. Riding along and the bike suddenly dies. If I turn the key off and on while coasting, the bike comes back to life and continues to run fine for 30 seconds or so before having to repeat that process. I thought perhaps it could be the fuel pump, but it dies instantly, no chugging or the like. So that fact has me doubting my diagnosis. Curious if anyone has any thoughts. Thanks a bunch.

 

[marsmax85]

When it does it again see if popping the fuel tank cap off and listen if it sucks air > It could be your vent pipe on top of fuel tank is clogged

 

[Fire-medic]

When was the last time you changed the fuel filter? Sounds like fuel starvation. Also examine the gas tank for rust, sediment and tiny hobgoblins.

 

[Jack01]

Hi all. Curious if anyone has any insights about the following issue. Riding along and the bike suddenly dies. If I turn the key off and on while coasting, the bike comes back to life and continues to run fine for 30 seconds or so before having to repeat that process. I thought perhaps it could be the fuel pump, but it dies instantly, no chugging or the like. So that fact has me doubting my diagnosis. Curious if anyone has any thoughts. Thanks a bunch.

Good tips/questions. I’ll check the venting, filter and pump. I’ve just never had fuel starvation result in instant shutting down on other bikes. There’s always some chugging, coughing, etc. This is more of the feel of a bad kickstand safety switch. Instant kill. But I don’t think that’s it because I don’t think toggling the key on and off would necessarily prevent the issue that I’ve been having. Thanks for the thoughts. Will update after I check the fuel.

 

[DirtieGirtie]

Do the jiggle!
Start the bike, pull in the clutch and put it in gear, and then have someone start jiggling different switches and contacts starting with the kickstand. I used to have a Magna that was known to have a dirty kill switch issue... the kill/run switch by your right thumb when dirty would cause the engine to die at inopportune times. Usually after you pulled over you could jiggle the switch and get it to run again.

 

[Fire-medic]

The sidestand switch gets corroded on its brass shaft, some WD40 or similar and working the spring-loaded shaft back & forth a few times will usually get it operating freely.

Yes to articulating wires to see if you can duplicate the issue, "Work it, baby, work it!"

https://www.vmaxforum.net/threads/h...f-the-throttle-side-switch-housing-pod.17272/
https://www.vmaxforum.net/threads/how-to-recondition-the-clutch-side-switch-pod.20783/
https://www.vmaxforum.net/threads/how-to-recondition-the-ignition-switch.17281/
Same as the last, as a Word .doc, easier to read/see.
https://cdn.imagearchive.com/vmaxfo...81bdfde073fb836e0743c0544fada8c05ca75e65f2db4

 

[Jack01]

Good tips/questions. I’ll check the venting, filter and pump. I’ve just never had fuel starvation result in instant shutting down on other bikes. There’s always some chugging, coughing, etc. This is more of the feel of a bad kickstand safety switch. Instant kill. But I don’t think that’s it because I don’t think toggling the key on and off would necessarily prevent the issue that I’ve been having. Thanks for the thoughts. Will update after I check the fuel.

Here’s the update: ended up being the CDI! The symptoms were too weird and inconsistent to be a fuel issue. The kill and safety switches didn’t seem to be problematic either. But it did feel like it was an electrical issue, so I dug deeper. Pulled out the CDI box. Looked perfectly fine and appeared to be well sealed. Took out the four screws that hold it together and a bit of water started to leak out. Ordered an aftermarket CDI from Amazon of all places for $150. Plugged it in and the bike runs perfectly. I have no idea how water made its way in there. Hope this helps somebody else down the line. Thank you to the folks who took the time to offer some suggestions.

 

[Fire-medic]

The wires from the plugs to the circuit boards cab break, or have an open circuit, too. Re-soldering them sometimes can fix it.

Only water in a CDI box I've seen is on a 'flood bike.' Post the web address of the vendor you used, please, it may help someone.

 

[MaxMidnight]

Out of curiosity, was the rubber front shield in place?

 

[Jack01]

Out of curiosity, was the rubber front shield in place?

Good question. It was!

 

[StanVM2007]

Glad you solved it! Too bad I didn't see this thread earlier as I would suggest CDI as well - based on my experience. Which I will describe in short below.

I wanted to upgrade and have more control over how the bike works, so I purchased Ignitech ecu unit. Using available proven maps - the bike kept acting funny. Lots of time spent on trying different settings with different results but not good. Just wouldn't run smooth and would loose power when fully warm.
It would be cutting off with rpm increase from still start at the traffic lights, and choking when riding on acceleration. Eventually, I gave up on scratching my head and looking for reasons everywhere else - including the carbs. I sent the unit back and got a full refund.

After installing the stock CDI back - voila! Just like that the Vmax was back. I've put a few thousand kilometers on the odometer since, and the bike never missed a beat. The Ignitech unit was brand new, but there was something wrong with it internally, which was amplified with the bike warming up. And I haven't touch anything else on the bike since, including the carbs.

In conclusion, people shouldn't dismiss the possibility that the CDI unit, new or old, might be faulty. I know you wouldn't expect that, but this happens. It's definitely handy to have a good spare for testing in your drawer.

To add to this story, many moons ago I used to work as a lift truck and all sorts of tow motors mechanic. Electric, fuel and propane. While it was a seldom accurance, some of the repairs of acting out units were traced to and solved by simply replacing the 'brain' of the truck. Why did they fail? While there was definitely a reason, we would never find out.

Another story is more recent, but still from the internet dial up connection era and the boot floppy discs. I had a hobby building my own 'supercomputers' (sounds silly now in 2023, L0L). I bought a brand new floppy disc drive. And couldn't make it work! Lots of troubleshooting back and forth, driver updates et. Nada. Took it back to the computer store and asked for exchange as I believed mine was faulty. They said.. impossible! Never happened! But they did check it quickly and indeed - brand new and dead. So, back to the conclusion - such rare things do happen so one should not dismiss such possibilities and keep the mind open.

By the way, Thank you Sean and Eric for all the remote assistance you guys did trying to solve that issue.