# Backfiring Brute??



## brutecamo (Mar 21, 2011)

My 08 750 Brute is backfiring almost everytime I let off the throttle or on decel. 
Seems worse at elevation. I think I remember the early carb version brutes cracking intake boots that led to backfiring and poor running. Anybody experience this on the newer FI Brutes? 
Gonna start rippin plastic off to check the intake boots unless somebody has another idea! :thinking:


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## BernardB (Jan 30, 2011)

Could be lean, Could be a screwed up or connection from your ECU (my current Problem). but i think running very lean would be the cause.. i could be wrong .


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## kdixer (Apr 14, 2010)

If it is worse at elevation then it is most likely a lean condition. 

you can check for an intake leak by spraying carb cleaner around the intake boots while it is idleing. You shoulld notice a difference in rpm's if it is leaking.


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## Floyd (Jun 1, 2010)

Could be a cracked exhaust pipe. My Muzzy Pro has a problem cracking where it flares out and bolts to the head. Once it starts to crack it starts back firing when I lift off the gas. The worse the crack gets the worse the back firing gets.


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## MeanGreenMan (May 24, 2010)

kdixer said:


> If it is worse at elevation then it is most likely a *lean *condition.


Isn't the air gets thinner as you go up the elevation, causing too *rich *condition?




Floyd said:


> Could be a cracked exhaust pipe. My Muzzy Pro has a problem cracking where it flares out and bolts to the head.


+1.
Look for hole or carck in the exhaust/muffler system, including the leaky gasket between the head pipe and the cylinder.

A coupled other things to check:
1. Fuel Pump - if there is lack of power issue at midrange to top end, this is it.
2. TPS - Check the setting to spec. It can mess up the F/A ratio.


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## MinnKawi (Jun 8, 2010)

My 08 will do it when cold on decel. Goes away after warmed up.


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## brute for mud (Jul 15, 2010)

it could be a small exhaust leak and when it heats up the leak goes away due to the fact metal expands when it heats up


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## kdixer (Apr 14, 2010)

Yup elevation causes a rich condition. Not sure where my head was.

I recently adjusted my mixture screw to eliminate some backfiring while decending a long downhill trail. It was too rich causing it to backfire while decelerating for several hundred feet with no throttle.

But both rich and lean conditions can cause backfiring. So back to the main clue, more backfiring at elevation should mean too rich. I had it backwards earlier.


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## cutter (Apr 10, 2011)

hey all i got a 07 750i brute and i swamped it i have changed the oil the plugs and the gas with a carb re build it idles great but when i open up the throttler it pops and back fires pleas any help on what it could be would be so great thanks for the read


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## Bigkuntry (Feb 8, 2011)

wat do u mean swamped if u drowned it check the coils make sure there firing i have 09 650 mine started that the front coil was bad


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## cutter (Apr 10, 2011)

*thanks for the help*

i found out that if the belt light is flashing it will run like S#&T lol re set the belt light and she lifts up the front end again


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