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08 Brute Force 750 no power going up hills and backfiring

17K views 27 replies 13 participants last post by  makls9 
#1 ·
I have a 08 Brute Force 750 efi. The atv started acting up on me, the problem is no power past 1/4 throttle no power going up hills or hard acelleration also startes to backfire and sputer, idles fine and startes fine. I been reading up a little and it seems it could be the fuel pump that is the source of the problem. I checked the spark plugs (good) all electrical connection (good and put dielectric greese) removed the old fuel and replaced with fresh supreme fuel with a shoot of water remover and still does it. I cant afford to bring it to the dealer but Im asking anyone for help and advice or other things the check out. I wish I still had warrenty coverage on it:(
 
#4 ·
if u havent had the valves checked/adjusted at this point you should do that for general purpose... the book calls for the first 1100 mi, then every 2200 after that... even the slightest bit off would cause loss of power, backfiring etc...

not saying this is FOR SURE your problem, but somethin to check anyway, if not just for piece of mind.
 
#7 ·
thats the belt reset kicking in... i havent hit 100 hs yet but there's gotta be a way around that, someone else will have to cover that haha
 
#8 ·
Yes Ive already been through the belt light coming on and rest it. and I know all about if a bad belt trip the switch the atv will only go 10mph and wont rev up. Its not that. I could use the valve clearance spec if you would have them Ill check that this weekend , but to me its still seems fuel or maybe electrical related and I cant afford to take it to the dealer thats my biggest problem and the warranty ran out at the begining of the mounth. I should of paid extra and got a CanAm:mad:
 
#9 ·
On cold engine:

Intake -- .004-.006 [0.10mm-0.15mm]
Exhaust -- .008-.010 [0.20mm-0.25mm]

not sayin it isnt elec/fuel... but this seems to be more probable of your issue... another thing u could check is your gas tank vent, make sure it aint clogged, or the hose aint off
 
#12 ·
My fuel pump puked at 500 miles and was a PITA to troubleshoot. PSI should be 43 which mine was...under warranty, the dealer had a hard time pinpointing it as it "tested good" .....on the trail, the more I road the worse it got. Let it sit for 15 minutes or more and it would be half a$$ OK and then start falling on it's face within a few minutes. Here's my thread on nyroc with more details.
Nyroc's ATV info website
If it is the fuel pump..guys have put different pumps in and saved a LOT of cash.... Chucked? I think has a corvette fuel pump thread on the site
 
#15 ·
Well Chuck750 I read your deal with your Brute and everything you said yours was doing thats what mine is doing. I tried it out the other daygoes like a bat out of hell on flats or down hill as soon as I go up an incline it startes to bog down and backfire like theres not enough fuel. But Im done with the warrenty so all repairs are coming out of my pocket and $500 is a little too much for me right now but Ill check other things like the valves, ignition etc again. :mad:
 
#16 ·
Since the new fuel pump which took my dealer a while to figure out..I've been using a Mr. Funnel AND a Profill sock filter for my tank...NO more dirt is getting in there!!! Almost 3000 miles and no problems...first failed in less than 500 but I didn't have the quad for those miles...that's why I bought the 4 year extended warranty..just had a feeling and $440 was cheap insurance. Good luck and let us know what you find.
 
#17 ·
Hello i have the same problem with my Brute force 750i i made with it 750miles and now i have a problem because when i accelerate at high speed the engine don't accelerate.. like something limited it,giving it more or less gasoline.Another thing...when i accelerate it slowly,the engine seems like working but the problem is when i accelerate suddenly.
 
#18 ·
:D Well Thanks to this web site My Brute is back healthy again THE PROBLEM = BAD FUEL PUMP and thanks to EBAY $460 free shippng for a new pump. Now she runs like a champ Thanks Chuck750 for your info and listing your same symptoms I had you where a great help and thanks to all who replied with suggestions now I can enjoy riding again and hope theirs no other problems anytime soon. Yee Haw ;)
 
#19 ·
beaulieu80, That's great to hear you're back on the trails again:tup: Too bad these fuel pumps cost so dam much though

Cozminbz - did you figure yours out yet? If you haven't yet, read my post from Nyroc (link is up a few posts) to see if that might help at all. Sounds like possibly same/similiar symtoms of what a few of us have seen.
And I still can't recommend enough to everyone to get a Profill filter for the tank...takes a little more time to fill (at the gas pumps) but it's better than letting any dirt in and wrecking our $500 fuel pumps...
 
#21 ·
It is generally dirt clogging the fuel pump sock on the bottom of it.

I had one of these a few weeks ago that was clogged with grass. how it got in there was beyond me. but it did belong to a lawn care guy who probably dumped gas can an unsealed can into the fuel tank.

it would start and run and idle up fine, but when it warmed up and you went over 40 mph it lost near 25 rwhp on the dyno. that's when the settled dirt in the tank would surround the filter on the pump.

John
 
#23 ·
Hey everyone thanks for all the info. My sons 2008 brute 750 is sitting in the shop now waiting on a new fuel pump. We have had all the same problems that everyone has described. Turns out that we didn't "VENT " the fuel tank check valve located next to the fuel tank and running thru the frame and sucking water, mud, and dirt into the fuel tank thus destroying the fuel pump and filter, when we put SNORKLES on it. Hope this helps, been troulbe shooting for eletrical for the last month and we finally took it to the shop to actuaLLY find the real problem and we probably want be fixed in time for TRAILFEST 2010 in West Virgina this year. O well the price we pay for playin the mud...
 
#24 ·
mine starting having the same problems, would run fine to wot for about a minute then start to crap out at 1/2 throttle and over (backfiring, missing , almost like its staved for fuel. It starts fine, idles fine, revs up in neutral, shut off for a few minuts and it is fine for a bit and this process repeats. I pulled out the fuel pump flow rate is good, looks good, went thru all connections.
Will only get to about 49mph tops, but any thing under half its good till you mash it.
It is running a bit lean on the front cylinder. I checked (new) plugs after it started doing this. Put another set in to make sure and it is running lean on the front one.
I dont know, think i will take into dealer tomorrow,
also put injector cleaner thru it, as well as some usual checks.
Anybody know what may be failing, and why only after a bit when its been running.
???
-o8 750i
Thanks
Mark
 
#25 ·
Fuel pump is my guess...same EXACT symtoms of what mine was doing 2 years ago- and everything checked good as well. Go back and read my Nyroc posting which has a link a few postings back. Good luck
 
#27 ·
Thanks Chuck, I read the post seems to be the same for sure, I took my fuel line off the pump and it pumps out straight about 1.5 inches steady stream, by looks at the pump it looks good i couldnt get to the screen in the bottom but what color are they, mine has a dark color to it white around the edges bit still see the holes in the mesh fine. It sat down for a month with little fuel and moving it could have sucked up some stuff, do you think maybe an injector may be plugged as well?

Also why wouldnt the back cylinder be missing more, the plug looks fine. not like the front,
I will look to buy a pump and try that, hope it works, kept the quad apart so wont be hard to change.
 
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