Intermittent Spark

[007sevens]

I need a little help, My pro loses spark. Here's the story.

Day one:
Unloaded the sled and ripped up the hills with no problem for about 3hrs. Then all of a sudden while climbing a hill it loses power and stops moving, noticed the gauge cluster cuts out and the engine flutters but stayed running while. It eventually dies but fires right up and after a bit it clears up and it runs fine for about 10mins. It cut out a few more times that day but always stayed running.

Day two:
Ran as it should for about 19kms on the trail at about an average speed of 60MPH. At the 19km mark we switched from trail riding to un-groomed trail with deactivation ditches which meant a slower speed. Sled cut out and stopped running as if it were shut off. It had no spark and never did recover. Pulled it off the hill and place it in a heated shop to thaw out snow under the hood. After about an hour of thaw time it fired up. Thinking it was the Throttle safety switch, I had it turned off in the ecm and rode the next day.

Day Three:
Made it 1Km down the trail when it cut out and quit running. Didn't wait to long pulled it down and handed it to mechanic in town and rented his sled. The mechanic walked into the trailer and it fired first pull. He changed out the voltage regulator thinking that was the problem. (He is not a Polaris mechanic) just a general mechanic.

Day Four:
Fired it up, backed out of the trailer but it hesitated a couple times. Hesitated up the trail a bit. It for the most part stayed running but did act differently then before with the other voltage regulator. It did not quit until after a long pull up the hill and as if you shut the engine off just as I turned around. Waited about five minutes it fired up and I started to drive down and it quit again. At the bottom of the hill I waited about ten minutes and it fired again. Feeling it was going to act up again I went down to the trailer. It never missed a beat and ran fine all the way down.

Day Five:
Back home. Unloaded out of trailer and placed in heated garage over night.

Day Six.
Went out to look at it and test it. Stator tests OK. Tried to start it, no spark. Pulled spark plug and no spark, then spark. Put spark plug back in, no fire. give it a little throttle and it fired up. low idle. Reset TPS through computer and fired and idled fine.

Notes:
2013 Pro Rmk
The sled has no bogs when running, when it acts up it is both cylinders. It acts just like you shut it off.

Any ideas, would be greatly appreciated.

 

[Trashy]

Coil or computer???

 

[007sevens]

Don't think its coils. Be funny that both fail at the same time. Not ruling out an ECM failure.

 

[Trashy]

Coils are pretty cheap, or if you know someone that you can swap with? ECM can be replaced under warranty.

 

[HotShotHarry]

Might want to check for kill switch wiring grounding out somewhere.

 

[007sevens]

Coils are pretty cheap, or if you know someone that you can swap with? ECM can be replaced under warranty.

Yes coils are cheap but the check out fine with an ohm meter. Not t o say they could fail when warmer but I highly doubt two would fail at exact time. You would think you would see one cylinder firing and the other not. Both cylinders go down at the same time. The ECU is a Vipec and it checks out fine with no codes showing.

 

[Trashy]

Yes coils are cheap but the check out fine with an ohm meter. Not t o say they could fail when warmer but I highly doubt two would fail at exact time. You would think you would see one cylinder firing and the other not. Both cylinders go down at the same time. The ECU is a Vipec and it checks out fine with no codes showing.

On older machines, the CDI would fail when it gets warm and was difficult to diagnose. I could see an ECM being similar. Just a thought?

 

[moto5151]

I had the mag pickups come loose. They would sit there and vibrate. Every once and a while I would loose spark. Pulled off the recoil and found all the little brass wires from the pick up. Also, does it have a tether? Double check the grounds, front left corner by bumper mount.

 

[007sevens]

I had the mag pickups come loose. They would sit there and vibrate. Every once and a while I would loose spark. Pulled off the recoil and found all the little brass wires from the pick up. Also, does it have a tether? Double check the grounds, front left corner by bumper mount.

Thanks. Been thinking of taking the recoil off to check for a rubbed through wire. The stator did check out fine with an ohms test.
I do have a tether but It was disconnected and that didn't help with the spark. The grounds are tight, but that doesn't mean they are not periodically not making contact. I will check them as well.

 

[007sevens]

So here what I have done to figure this out. I've checked the kill switch and the tether. They're fine. Tested the coils, hand warmers, thumb warmer, Stator, exhaust valve solenoid, voltage regulator, fuel pump resistor, everything checks out. I checked TPS manual adjustment and it is within spec. I gave the sled a good look over for anything out of the ordinary and nothing looks wrong. I'm stumped. As of right now you can start sled with one pull and it runs as it should. Might have to put it back together and see if I can recreate the problem.

 

[nwoprormk]

Hi not sure if this will help. Have a 12 SBA.... Started doing exactly what u describe the other day. Thought it may have been fuel related at first because there was no backfire.... But realized that with F.I. Id assume if the power was interupted the injectors would stop fueling therefore eliminating any raw fuel in the pipe to cause the backfire. That being said i found that the epoxy filling they put in the cdi box ( next to the coils) to protect the circuit board had began to fail where the three wires enter it... Probrably from the repeated bouncing motion of the harness and plugs while riding. I sealed i with some black rtv and tie wrapped the harness to prevent movement.50 miles since with no sign of shutdown or misfire. Time will tell. My next c option was gonna be the deadmans switch on the throttle.... But not the switch itself. The wiring harness takes alotta twisting where it runs down the steering shaft. Have had wores in there break in the first season. Guess even poo is using too much recycled copper in their harnesses.....hope this helps

 

[007sevens]

Well, I went for a ride today to see if I could get it to fail so I could test it. I couldn't so I came back to dig further. I was told to check where the water pump for my water to air intercooler. It checked out fine but when I pulled the fuel tank back to inspect it (its mounted right in front of the fuel tank) the wires to the fuel pump came taught and there it was. A short in the red lead wire to the fuel pump.

Now I have another question for you guys. Is there a fail safe built into the stator to protect it against damage from a short like this.