09 D8 Randomly dies and won't start back up!!

[Zone28M7]

Alright so I'm sure there are many threads on this but can't seem to find this exact topic. My brother has 2009 800. It's mainly stock other than an SLP pipe and can. Last season he had to replace the voltage regulator as well as the ecu. This year he's had chronic issues with having to change the plugs because after an hour of riding the plugs are sopping wet. Also every time he starts it he has to hold the throttle down or it won't start. Additionally it will randomly quit running and won't fire back up. Upon trying to pull start it a dozen times it will eventually backfire very violently. This one has us stumped pretty good...

TPS?
Voltage regulator?
Kill switch?
Ecu?


Could really use some help on this one and really hoping someone has run into this exact scenario.


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[BB454]

09

If throttle cable is loose, you will see intermitten ignition and hard starting. Check and make sure it is tight enough to keep the dead man switch under the throttle lever closed. Check that first.

Did you put a new ecu on of used? I would borrow a ECU from someone and see if that fixes it. Due to it being fuel injected, you should not have a wet plug problem nor a flooding issue which is what it sounds like requiring the throttle to be held open to start it. Only way it could flood it if the ecu is telling the injectors to give it too much fuel or injector is bad but you have 4 so I don't think they are all bad. Ecu also controls spark so that is why it may shut down after a while and also backfire. If you push raw fuel into the pipe and the get a spark when the exhaust port is open .... bang!!

 

[Zone28M7]

If throttle cable is loose, you will see intermitten ignition and hard starting. Check and make sure it is tight enough to keep the dead man switch under the throttle lever closed. Check that first.

Did you put a new ecu on of used? I would borrow a ECU from someone and see if that fixes it. Due to it being fuel injected, you should not have a wet plug problem nor a flooding issue which is what it sounds like requiring the throttle to be held open to start it. Only way it could flood it if the ecu is telling the injectors to give it too much fuel or injector is bad but you have 4 so I don't think they are all bad. Ecu also controls spark so that is why it may shut down after a while and also backfire. If you push raw fuel into the pipe and the get a spark when the exhaust port is open .... bang!!

Yeah I'm actually banking on this being in either the tps or the connection between the kill switch and throttle. I don't think it's the ecu because the regulator and ecu were replaced new last year.



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[Zone28M7]

If throttle cable is loose, you will see intermitten ignition and hard starting. Check and make sure it is tight enough to keep the dead man switch under the throttle lever closed. Check that first.

Did you put a new ecu on of used? I would borrow a ECU from someone and see if that fixes it. Due to it being fuel injected, you should not have a wet plug problem nor a flooding issue which is what it sounds like requiring the throttle to be held open to start it. Only way it could flood it if the ecu is telling the injectors to give it too much fuel or injector is bad but you have 4 so I don't think they are all bad. Ecu also controls spark so that is why it may shut down after a while and also backfire. If you push raw fuel into the pipe and the get a spark when the exhaust port is open .... bang!!

Also how doi check the dead man switch under the throttle lever?

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[BB454]

safety switch

Both the dead man switch and the auxiliary shut off on the throttle block are wired to the same plug in the harness. 3 wire plug with BK/BU, BK, and RD/BK. You should be able to unplug it and it should still run. You will have to turn it off with the key switch. If it starts easily then your problem is in the switches. You should have continuity between BK/BU and RD/BK when the throttle is closed and the kill switch in the run position. If not, try cycling the kill switch and see if you get anything different. If you have continuity, squeeze the throttle an see if it drops. If so that is how it it supposed to work. If no continuity try applying pressure at the pivot point on the lever and see if you get it. If you do then throttle cable is too loose. When the kill switch is closed you will see continuity between BK and RD/BK

That switch is actually under the pivot pin on the throttle lever. Look closely and you will see the hole in the throttle block is elongated.

BK/Bu goes to ground, BK goes to ignition switch and on to the tether connector, make sure it isn't touching a ground if you don't have a tether. RD/BK goes to ecu.
Good luck

 

[Zone28M7]

Both the dead man switch and the auxiliary shut off on the throttle block are wired to the same plug in the harness. 3 wire plug with BK/BU, BK, and RD/BK. You should be able to unplug it and it should still run. You will have to turn it off with the key switch. If it starts easily then your problem is in the switches. You should have continuity between BK/BU and RD/BK when the throttle is closed and the kill switch in the run position. If not, try cycling the kill switch and see if you get anything different. If you have continuity, squeeze the throttle an see if it drops. If so that is how it it supposed to work. If no continuity try applying pressure at the pivot point on the lever and see if you get it. If you do then throttle cable is too loose. When the kill switch is closed you will see continuity between BK and RD/BK

That switch is actually under the pivot pin on the throttle lever. Look closely and you will see the hole in the throttle block is elongated.

BK/Bu goes to ground, BK goes to ignition switch and on to the tether connector, make sure it isn't touching a ground if you don't have a tether. RD/BK goes to ecu.
Good luck

A polaris dealer is reflashing the tps today. If the issue still persists then we will monkey with throttle cable and wiring that you mentioned. I'll keep updating


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