&@#$*!!!! Need help diagnosing electrical problem - TwoWheelForum: Motorcycle and Sportbike forums
 
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post #1 of 5 (permalink) Old 06-05-2008, 10:22 PM Thread Starter
 
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&@#$*!!!! Need help diagnosing electrical problem

I've been having a problem with my YZF750R that I can't seem to diagnose. I can ride for a little bit fine, but after about 10 min or so the bike starts sputtering, backfiring, etc. Gets worse and worse till bike shuts off. Once it cools off, I can start and ride a bit more, till heats up again. I replaced the coils (with used ones off a low mileage bike), and than it ran great for about 2 weeks then the same thing happens again. I ordered new caps, boots, coils, and replaced everything with new OEM parts but the problem is still there. Any help diagnosing the problem would be appreciated.

Thanks
-- Matt
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post #2 of 5 (permalink) Old 06-05-2008, 10:46 PM
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Did you happen to open your fuel tank to check the vented gas cap????
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post #3 of 5 (permalink) Old 06-06-2008, 03:18 PM
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Quote:
Originally Posted by indianaroadracer View Post
Did you happen to open your fuel tank to check the vented gas cap????

+1 or the fuel filter? Try riding around with the gas cap open once and see if it does it again. Sputtering is almost always fuel delivery and not electrical. By moving the tank around to get to the plugs,you may be dislodging whatever is causing the problem. Once things settle back down,the problem resurfaces. You may even have some crap in the tank that is blocking the screen on the pump,if you have an in/on tank pump.

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post #4 of 5 (permalink) Old 06-07-2008, 12:40 AM Thread Starter
 
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thanks guys. I checked the fuel system today. No blockage on the vent line or tube, riding with the gas cap open didnt help. Fuel filter OK, fuel pump pressure is good. I was and am still skeptical of a fuel issue, because the bike is backfiring erratically, not just sputtering like its starving for fuel.
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post #5 of 5 (permalink) Old 06-07-2008, 04:17 PM
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Did you check the tip-over sensor? Neg batt terminal? Hmmm....

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