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My older friend whom does not have access to the net, has been battling an electrical gremlin with his 87 TRX 350. Everything was working perfect until it started dieing on him when puting it into gear. It starts perfect and idles great. Most of the time it would run down the road without any problem at all but would just die every once in a while while driving. It then progressed to dieing when puting it in gear after starting up and idling without any problem. Eventually progressed to not being able to put it in gear without dieing every time.

Internet searches pointed to the fan control switch. Ordered a used one since you can't get a new one any longer. This fixed the problem! But just for a short period of about two weeks and the same problem started again.

Is there a way to bypass the fan control switch? Or what could possibly be making this part to go bad??
 

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My older friend whom does not have access to the net, has been battling an electrical gremlin with his 87 TRX 350. Everything was working perfect until it started dieing on him when puting it into gear. It starts perfect and idles great. Most of the time it would run down the road without any problem at all but would just die every once in a while while driving. It then progressed to dieing when puting it in gear after starting up and idling without any problem. Eventually progressed to not being able to put it in gear without dieing every time.

Internet searches pointed to the fan control switch. Ordered a used one since you can't get a new one any longer. This fixed the problem! But just for a short period of about two weeks and the same problem started again.

Is there a way to bypass the fan control switch? Or what could possibly be making this part to go bad??
Anyone have any ideas?
 

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welcome to the forums, sorry I did not see your post earlier ?, your buds trx350 fourtrax needs a new c.d.i. :).
 

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I don't understand why a fan switch would cause this problem - never heard of that around here. On a bike of that age, I'd be more concerned with a CDI going bad or a voltage regulator / rectifier problem. Do you own a good multimeter?

The next time this happens, tap on the CDI while cranking. Does it restart?

Rick
 

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I don't understand why a fan switch would cause this problem - never heard of that around here. On a bike of that age, I'd be more concerned with a CDI going bad or a voltage regulator / rectifier problem. Do you own a good multimeter?

The next time this happens, tap on the CDI while cranking. Does it restart?

Rick
the fan works off the fan control unit, which in turn, wired to the c.d.i. these atvs have a built in safety feature for the oil temp sensor, if they over heat ?, the fan kicks in, if the fan does not kick in, either by the sensor ?, or the fan control unit ?, the c.d.i. cuts power to the spark plug to keep the motor from seizing, this info is listed in the tech section in the service manual :).
 
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Mine would not start at all until I swapped out the cdi never any problems since then. I have been looking for an opportunity to check out the old cdi--it has a crack in the sealant. If you have a Foreman the wire colors will be different from this Fourtrax cdi tshoot table
 

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Discussion Starter #7
I don't understand why a fan switch would cause this problem - never heard of that around here. On a bike of that age, I'd be more concerned with a CDI going bad or a voltage regulator / rectifier problem. Do you own a good multimeter?

The next time this happens, tap on the CDI while cranking. Does it restart?

Rick
the fan works off the fan control unit, which in turn, wired to the c.d.i. these atvs have a built in safety feature for the oil temp sensor, if they over heat ?, the fan kicks in, if the fan does not kick in, either by the sensor ?, or the fan control unit ?, the c.d.i. cuts power to the spark plug to keep the motor from seizing, this info is listed in the tech section in the service manual :).
Thank you for the replies and input. It never has a problem starting. Will start and idle perfect every time. Just dies right away when puting it into gear.
 

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I don't understand why a fan switch would cause this problem - never heard of that around here. On a bike of that age, I'd be more concerned with a CDI going bad or a voltage regulator / rectifier problem. Do you own a good multimeter?

The next time this happens, tap on the CDI while cranking. Does it restart?

Rick
the fan works off the fan control unit, which in turn, wired to the c.d.i. these atvs have a built in safety feature for the oil temp sensor, if they over heat ?, the fan kicks in, if the fan does not kick in, either by the sensor ?, or the fan control unit ?, the c.d.i. cuts power to the spark plug to keep the motor from seizing, this info is listed in the tech section in the service manual :).
Thank you for the replies and input. It never has a problem starting. Will start and idle perfect every time. Just dies right away when puting it into gear.
yep, your c.d.i is bad, i'll bank on it !.
 
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