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Discussion Starter · #1 ·
Here is my problem with my bike, starts and runs perfect i'll be running down the road and all of a sudden it is like the motor cuts out if i downshift quickly back to neutral it will stay running but if i don't it shuts down. It starts right away then when i put it in gear it stalls, starts right away again goto put in gear it stalls, start again let it set idleing for a min and it is fine for awhile. it has been doing this for about a year now. my kids Ran it all last weekend no problems i get on it start going get 500ft then it stalls then it goes away sorry so long but just frustrated any suggestions would help don't know where to look some say it could be carb issue but just don't get that if i get it back to neutral it will run all day.
thanks in advance

Todd
 

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It might be a carb problem, but it could also be a weak fuel pump or stopped up fuel filter. My guess is a weak fuel pump.

I think those models also have a fuel pump control unit that regulates the fuel pump and that could also be the problem, but my guess is still the fuel pump being weak.
 

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Discussion Starter · #3 ·
thanks Helmut for the reply so how can i tell if the fuel pump is weak i did pull off the hose from the end of the fuel pump seem to be ok but how do i know it is weak?
 

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thanks Helmut for the reply so how can i tell if the fuel pump is weak i did pull off the hose from the end of the fuel pump seem to be ok but how do i know it is weak?
I'm not sure about that. You would have to do a pressure and flow test, but I don't know what the pressure should be. There's probably a fuel pump flow and pressure test in the repair manual, but I don't have a manual for the TRX350. When Shadetree gets back on here, he can probably tell you as he just finished restoring one of those quads and he knows a lot about them. Seems like I remember reading on here, that he said, you could buy an electric fuel pump at the auto parts store that will work on the 350, but I can't remember which auto parts store or which fuel pump he said.
 

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Discussion Starter · #5 ·
thanks again i do have a message out to him but have not heard back yet this problem is really stumping me i just can't understand why it is an intermitten problem also do you have any idea when the oil cooler fan comes on i have never heard it run and how can i check it if you know
 

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thanks again i do have a message out to him but have not heard back yet this problem is really stumping me i just can't understand why it is an intermitten problem also do you have any idea when the oil cooler fan comes on i have never heard it run and how can i check it if you know
Have you gotten the engine pretty warm. It has to get pretty warm before the fan will kick on.

There should be a thermo sensor somewhere on the block that cycles the fan on and off when the engine gets a certain temperature and it could be bad. Also, if the thermo sensor isn't bad, there's probably a relay or control unit somewhere in the circuit, but I don't know which one. It's been a long time since I've worked on one of those TRX350's. When you find the thermo sensor, if it's just got a singe wire going to it, you should be able to test the sensor by unplugging the wire and touching the wire to a good ground such as the engine crankcase. Don't forget to have your key on when you test it. All the thermo sensor does is to ground and complete the circuit when the engine gets a certain temperature. That's how it works on most ATVs, but if the thermo sensor has more than one wire, then don't ground anything because it might short something out. If it only has one wire going to it, then it has to be a ground. If it was a hot, it would short out when the switch closed.

If the thermo sensor is good, then you could try running 12 volts straight to the fan to test the fan.
 

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Discussion Starter · #7 ·
thanks for all your helpful information i'll see what i can find out when i head back north in a few days
 
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