Mystery problem

[Machine1964]

OK it's done it to me twice now.My '92 is running just fine then all of a sudden it starts popping real bad thru the exhaust,dies and won't restart.First time for a day second time for an hour.Then it restarts and runs fine.When it tries to restart it right away it will sometimes restart,idle fine,then if any throttle is given it will backfire and die.Battery is good and fuel pump is pushing fuel.Anybody heard of this.Electrical?Ignition...maybe?

 

[SpecOps13]

Just by chance, sounds like Vapor Lock, a carb problem...:ummm:
How hot is the temperature there right now?

Good Luck,
Dave

 

[Rhoy Carter]

Check the tank vent

 

[Machine1964]

First time it was 75 degrees second time it was 85 degrees

 

[Machine1964]

BTW, Where is the tank vent ?

 

[SpecOps13]

Good thought. Run it and when you take a break, pop the gas cap to see if there's a rush of air... I did have that problem with my 89....

 

[wildweasel_pt]

Might be a problem on the ignition unit as well causing misfire and thus the backfire...

 

[Machine1964]

Okay here's the update.The headlight (and only the headlight)no longer comes on when the key is in the on position.All other lights come on and are bright.Battery is fully charged and absolutely no spark.Any ideas?(edit)Also motor turns over fine just won't fire.

 

[sdt354]

I'd by pass the key switch to eliminate it as a problem. It won't cost a penny, just a few minutes. Shunt all connections together at the ignition switch plug. If the light comes on, and it now runs, it's switch time.This will also get you home if the ignition switch goes on the road sometime.
Steve-o

 

[KJShover]

Okay here's the update.The headlight (and only the headlight)no longer comes on when the key is in the on position.All other lights come on and are bright.Battery is fully charged and absolutely no spark.Any ideas?(edit)Also motor turns over fine just won't fire.

If the start button is a little stuck might cause this. When you start the Vmax, it shuts off the headlight to put more juice to the starter.

Also check;
Side stand switch
Neutral switch
Red engine stop switch

 

[naughtyG]

I second KJ - check and clean your start button, and check out your killswitch while you're there.

 

[SpecOps13]

Come to think of it, I had to clean those switches on my 89...:bang head::confused2::ummm:

 

[94 V-Max Rider]

Okay here's the update.The headlight (and only the headlight)no longer comes on when the key is in the on position.All other lights come on and are bright.Battery is fully charged and absolutely no spark.Any ideas?(edit)Also motor turns over fine just won't fire.

The problem sounds like it's in the right hand handlebar switch assembly. When you press the starter button, it momentarily shuts off the headlight to prevent excessive current draw. The switch may be dirty or in need of replacement. The whole issue with no ignition sounds as though it may have to do with the engine stop switch. Check the starter and engine stop switches for continuity.

 

[Machine1964]

You'll never believe what the problem turned out to be. Bad fuses not blown bad.
2 of the fuses under the tank looked old so I replaced them and the problem went away. Happened to be the ignition and headlight fuse. Thought fuses were either good or blown,didn't know there was an in between.

 

[wildweasel_pt]

That doesn't explain the sudden stall and backfire...

 

[Machine1964]

Been running fine for two weeks now and then the problem comes back with a twist.If I don't give any throttle it starts and idles fine.As soon as the tach hits 3000 it starts popping real loud and if I don't back out of the throttle it will die.I'm stumped.Ready to put it in the garage and give up riding.

 

[bazwell]

Reading this I'd say you still have a bad connection. Probably in the switch.
I can't remember who had the same problem, maybe 6 months ago, but it was exactly the same. He would get to a certain number of revs and the harmonic vibrations would cause the bad connector to vibrate a little. He cleaned out the switch and it went away.

In your case though, it might be the little terminals where you plug the fuses in. I mean, it wasn't a blown fuse (like you said), but the action of pulling a fuse in and out cleaned the terminal a bit.

Don't give up! Get a can of electrical contact cleaner and clean those suckers!

 

[naughtyG]

I agree with Baz - bad electrical connection.

Get the contact cleaner and check all the connections near the fuses you replaced, but also and especially the starter button, killswitch and safety switches (clutch, sidestand, neutral).

Also take a good look at your wiring harness at places that come under constant stress, such as the bits by the top front of the frame that move every time you turn the handlebars.

 

[Machine1964]

Ok cleaned all switches thoroughly.Now i have no fire at all to any of the plugs.I think this is extension of the last time I started it.It popped real loud then wouldn't start again.Gave up closed the garage.Went out today and cleaned all the switches(and they were full of gunk).Tried to start it and no fire.Bad TCI unit maybe?Ever seen one go slowly bad then give up?

 

[Fire-medic]

Try RaWarrior's sticky about electrical trouble-shooting.