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Old 11-18-2009, 03:24 AM   #1
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Default Motor Issue

Hi guys ive got a motor problem and would love some suggestions on how to fix it

When i over prime my motor it starts up no problem and once the fuel in the carby has gone the motor stalls.. there are no blockages that i can tell and ive check my exhaust back pressure already.. so im very confused!!!

Any help would be appreciated. Even the same things ive already checked ill re-check if someone feels confident thats the problem

Thanks!!!
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Old 11-18-2009, 03:34 AM   #2
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We had a simular scenario at my local offroad track on the weekend, The engine would run when primed but would soon run out of fuel... We started to check for leaks (fuel tank etc) and tried for ages re tuning it, After i had spent half an hour on it another three or four guys looked at it and eventuly one bright spark found that the pressure nipple on top of the tuned pipe where the pressure hose connects was blocked.. after running a small driver thru it and cleaning it out the buggy ran fine

Funny thing is that it was a brand new rtr hyper kit

Anyway you said you checked your backpressure so i guess thats not your problem... Try checking your fuel tank/lines for leaks, put the tank under water and blow into it and make sure no bubbles escape etc



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Old 11-18-2009, 06:09 AM   #3
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after going through everything with the most care ive ever taken in my life.. there is the smallest most tiny little impossible to detect leak in my fuel tank right up the top where there in no fuel... could this little thing make a difference?! its soooo tiny it makes no difference when priming though!!
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Old 11-18-2009, 01:02 PM   #4
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Is this a new motor ? Was anything done to it before this issue started ? When i had an issue like this, it was a piece of the oring from on of the carb needles block in the fuel path.
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Old 11-18-2009, 01:07 PM   #5
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Quote:
Originally Posted by kypreo View Post
after going through everything with the most care ive ever taken in my life.. there is the smallest most tiny little impossible to detect leak in my fuel tank right up the top where there in no fuel... could this little thing make a difference?! its soooo tiny it makes no difference when priming though!!
If it's at the top of the tank it could cause the problem. Depending on how you are priming the system you are probably creating more pressure in the tank than the exhaust pressure does while running. If the leak was on the seam of the tank it would normally run great until it uncovered the seam laek and then you would lean out or die.
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Old 11-18-2009, 01:36 PM   #6
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The leak will be your problem for sure... your fuel system including the pressure line side to a degree has to be leak free for everything to work


Let us know how it goes when you fix the leak and re tune it





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