# 08 Brute trouble



## zach93 (Jul 13, 2011)

Hey guys,
My dad is having troubles with his 08 brute 750, after about 15 minutes of driving it will start to run bad and sputter at anything over 1/3 throttle. this winter we did a rad relocation however the fan cycles on and off and coolant is flowing good. we replaced coils, wires and boots with oem parts. the other night when riding the muffler got very hot and on the exhaust pipe just before the muffler was red hot. we have no idea what is wrong with it. what do u guys figure?


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## blue beast (Feb 16, 2010)

i think to have the exhaust glowing ,its lean(somebody please correct me if im wrong)...the spitting and sputtering ..i would probably check for water in the tank,,, clean the tank and lines.....then use fuel stabilizer in it when its gonna set up for a while..should be some more techinical ideas, just cant think of any right now...


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## wcs61 (Jun 7, 2011)

Well you would think that it's lean but I'm sure with further details you may find it's running rich. As per what they tell me on my glowing pipe.
First they will want to know what mods have been done to the engine and electrical. Then they will ask about snorkels and size of intake snorkel. Just saying...


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## wyo58 (May 13, 2011)

zach93 said:


> Hey guys,
> My dad is having troubles with his 08 brute 750, after about 15 minutes of driving it will start to run bad and sputter at anything over 1/3 throttle. this winter we did a rad relocation however the fan cycles on and off and coolant is flowing good. we replaced coils, wires and boots with oem parts. the other night when riding the muffler got very hot and on the exhaust pipe just before the muffler was red hot. we have no idea what is wrong with it. what do u guys figure?


Yeah I agree with the others any other mods?


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## jrpro130 (May 10, 2009)

First thing I would check is fuel pump! Sounds like the 1/3 throttle sputter


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## blue beast (Feb 16, 2010)

we need to know all the mods he has on it...i was just guessing on the first post


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## zach93 (Jul 13, 2011)

the only mods are the rad relocation, could the muffler be plugged and causing to much back pressure? i only saw a small portion of the exhaust pipe just before the muffler red hot.


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## wyo58 (May 13, 2011)

zach93 said:


> the only mods are the rad relocation, could the muffler be plugged and causing to much back pressure? i only saw a small portion of the exhaust pipe just before the muffler red hot.


It's possible there is a clean-out in the bottom of the muffler might try using that to see.


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## filthyredneck (Feb 10, 2010)

I agree with doing a flow test on the fuel pump... see what it spits out in liquid oz when you first turn the key on. It could be something as simple as the fuel pump strainer (fuel filter) being dirty and not allowing enough flow, or it can be something more drastic like a weak pump. You can change the strainer, will run ya around $15 from Autozone. Another thing that could be taken into consideration is the throttle position sensor (TPS), they aren't a real common thing to go out...but it does happen. I had to change the one on my 08. First things first though check your flow on the fuel pump, I'd just unplug the fuel line from the tank and slip a new piece of hose over the nipple right there and have a measuring cup or bottle ready to catch the gas when you turn the key on....you should cycle the key once to reprime everything since you are removing the primed fuel line before actually trying to collect an accurate measurement. (have to do a search on here and find the range that its suppost to be in....I think its a little over 2oz up somewhere near 4oz when you turn the key on) I can pitch in a little more on this topic later, gettin ready to swimmin out at the spring fed creek about 25 mins from the house .

Heres my flow test results, and also the new strainer part # that I used on the fuel pump, its a little longer than the stock one but works fine, and also what my old strainer looked like


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## zach93 (Jul 13, 2011)

if it were fuel pump why would it rip for the first 15 minutes. it runs like it always did for 15 minutes then it bogs out and i can only get about 1/3 throttle?? yeah there is a cleanout plug on the bottom of the muffler, i tried that once but not much came out, i'll try it again. i dont think it is fuel pump cause it rips for 15 minutes but maybe theres something i dont know about that.


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## zach93 (Jul 13, 2011)

k so i tried cleaning the muffler by pulling the plug on the bottom and hitting it with a hammer while revving it. nothing came out. the muffler seems to work fine. exhaust seems to be flowing fine


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## hp488 (Sep 23, 2009)

:agreed:


filthyredneck said:


> I agree with doing a flow test on the fuel pump... see what it spits out in liquid oz when you first turn the key on. It could be something as simple as the fuel pump strainer (fuel filter) being dirty and not allowing enough flow, or it can be something more drastic like a weak pump. You can change the strainer, will run ya around $15 from Autozone. Another thing that could be taken into consideration is the throttle position sensor (TPS), they aren't a real common thing to go out...but it does happen. I had to change the one on my 08. First things first though check your flow on the fuel pump, I'd just unplug the fuel line from the tank and slip a new piece of hose over the nipple right there and have a measuring cup or bottle ready to catch the gas when you turn the key on....you should cycle the key once to reprime everything since you are removing the primed fuel line before actually trying to collect an accurate measurement. (have to do a search on here and find the range that its suppost to be in....I think its a little over 2oz up somewhere near 4oz when you turn the key on) I can pitch in a little more on
> this topic later, gettin ready to swimmin out at the spring fed creek about 25
> mins from the house
> 
> ...


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## wyo58 (May 13, 2011)

Then I would do a flow and pressure test on the fuel system. It is also possible that somebody dropped something in the fuel tank and it's taking time to get over to plug up the fuel pump, but that is pretty rare. The srevice manual says a minimum of 1.7 oz in the 3 seconds when the key is turned on, but it is usually quite a bit higher than that. Also you need 43 psi of fuel pressure at idle minimum.


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## zach93 (Jul 13, 2011)

my buddy who is a mechanic figures its running lean. he told me to spray some carb cleaner on the boot in between the throttle body and the head. apparently these are common on brutes. if this doesnt reveal anything i'll try the fuel flow test. also buddy told me it could be the belt switch. he told me on his that the belt switch flipped but the light didnt come on. when the switch is flipped does it run could for awhile then bog out or does it run crappy all the time?


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## filthyredneck (Feb 10, 2010)

If the belt switch is tripped inside the case then it should run crappy all the time, not just once it warms up. Theres not much to testing the fuel pump, it can be done with all the plastics still on the bike, just loosen the bolts that hold the electronics tray down under the seat so that you can lift it up a little to pull the red clip off of the end of that fuel line and pull the line loose, slip your test hose back over the nipple and then just turn the key on. Its that simple to check the flow. OR, if your mechanic buddy has a fuel pressure gauge then y'all could hook that up and ride it around and when it starts to run bad see if the fuel pressure has dropped any. As far as it running bad because its lean....maybe somebody will speak against me here, but from my experience a lean bike actually has more power at the seat of the pants than one that is a little richer running (it'd have to literally be STARVING for fuel to just loose power), I do believe that you are on the lean side though do to the fact that the headers are glowing...that definitely points to lean like your friend already stated. A friend of mine ran into a similar problem a couple weekends ago, we narrowed it down to his TPS, and in the end it was TPS related....somehow he managed to pinch one of the wires in half on the harness that plugs up to the TPS (we are guessing he did it somehow when he installed his new wire harness that he bought), he bought the new TPS before inspecting the wires and when he got ready to install it thats when he noticed the break. I'm not suggesting that your wires are messed up, but a malfunctioning TPS can actually act like a choke sometimes, and will often result in the motor not idling or sounding like it has really big cams when it starts to give up....and it will sometimes have to actually get hot before it starts to give any issues. Get your hands into it a little more and let us know what you come up with, I'm positive that at least one of these guys on here can get ya lined out once you test a few things.


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## zach93 (Jul 13, 2011)

i did notice that the odd time when it runs it sounds like it misses. not severe but there is a change in idle for split second. did your buddys quad run awesome for a bit then run crappy when the tps was bad. Is there anyway to test if the tps is good? also i noticed that if i let the brute cool down for a minute or two after it starts to act up it will run good for a little while again until it heats up back to the point where it bogs out. but if its fuel pump WHY would it bog out after riding it for awhile. Why wouldn't it do it from start up.


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## nathen53 (Jun 13, 2011)

Sometimes when a fuel pump begins to warm up thats when its start loosing its pressure.....So like Filthy said put a fuel gauge on it and ride it until it starts acting up and see what it shows


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## oft brute (Jul 22, 2011)

nathen53 said:


> Sometimes when a fuel pump begins to warm up thats when its start loosing its pressure.....So like Filthy said put a fuel gauge on it and ride it until it starts acting up and see what it shows


 on the fi's always check the pump. it's almost always the problem.


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## wyo58 (May 13, 2011)

It's true one of the main reasons high pressure fuel pumps were put into cars (and FI atv's) inside the fuel tank was because of heat. They get pretty warm pumping fuel at high pressures. On vehicles, any in line pump thats outside the tank is usually pretty big in size. It has thicker metals around it to disipate the heat. So if the pump is weak or the screen is plugged, it's working harder to keep up demand (not building pressure above the regulators bypass valve). So I'd go with the flow test both cold and when it starts to act up, just like FRN said. Then if those results don't give you all the info to rule out the pump, then do the same tests with a pressure gauge.


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## zach93 (Jul 13, 2011)

i checked the intake and everything is sealed tight so we are thinking fuel pump now. should the pump flow the same amount of fuel idleing hot and cold? also should the fuel pressure rise when driving? Kawi says the filter cant be changed and that we have to replace the whole pump. has anyone taken apart the pump and replaced just the filter?


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## filthyredneck (Feb 10, 2010)

Yes the filter can be changed. Myself and many others have done it. I put a part number further up this thread that does for sure work.


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## wyo58 (May 13, 2011)

zach93 said:


> i checked the intake and everything is sealed tight so we are thinking fuel pump now. should the pump flow the same amount of fuel idleing hot and cold? also should the fuel pressure rise when driving? Kawi says the filter cant be changed and that we have to replace the whole pump. has anyone taken apart the pump and replaced just the filter?


You can't do a flow test running, but you can do it with it warm and cold. The fuel pressure should stay at 43 psi regardless of engine rpm with a maximum of 43.5 psi. It takes very little less in pressure to run poorly.

FRN has done the filter change so he knows it works for sure. The reason Kawai say it's not replaceable is they don't really want people messing inside the pump module, but a filter change will cause zero problems and FRN already has the number to use, scroll up.


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## filthyredneck (Feb 10, 2010)

The strainer is located at the very bottom of the pump assembly. Just unlock the little plastic tabs that hold everything together and pull it apart. The strainer just pops off the end, mine took a little effort to break loose. The new strainer just slides back on and then slip everything back together. As far as kawi sayin it can't be done, this also means that they will say theres not another filter that'll fit.... Wrong. This AIRTEX strainer from Autozone fits almost like the stock one, its just a tiny bit longer. This isn't the only one that will work, but it gets the job done and its only around $15.


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## zach93 (Jul 13, 2011)

can the strainer be cleaned? we are gonna pull the pump soon and check it.


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## filthyredneck (Feb 10, 2010)

I guess it could be....maybe. Personally if I was in there I'd just throw a new one in it though unless you get it apart and can tell that its not dirty.


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## wyo58 (May 13, 2011)

filthyredneck said:


> I guess it could be....maybe. Personally if I was in there I'd just throw a new one in it though unless you get it apart and can tell that its not dirty.


X2, can't see going to all the trouble of taking it out of the tank and just cleaning it. Replace it.


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## oft brute (Jul 22, 2011)

wyo58 said:


> X2, can't see going to all the trouble of taking it out of the tank and just cleaning it. Replace it.


 x3 /\ /\ /\


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## zach93 (Jul 13, 2011)

FRN, when u replaced the strainer were u able to put that bottom cover back on the fuel pump?


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## zach93 (Jul 13, 2011)

checked fuel pressure and fuel flow. fuel pressure was good until it warmed up then it dropped to 22psi when revved. only got one and a half ounces of fuel when we did the fuel flow test.


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## filthyredneck (Feb 10, 2010)

zach93 said:


> FRN, when u replaced the strainer were u able to put that bottom cover back on the fuel pump?


Yes sir no problems there...the sock itself is a little longer so it slightly curls up on one end inside that cover, but the rest of it fits fine.



zach93 said:


> checked fuel pressure and fuel flow. fuel pressure was good until it warmed up then it dropped to 22psi when revved. only got one and a half ounces of fuel when we did the fuel flow test.


Truly sounds like a bad pump. Do you know anybody with a FI brute who would let you take their gas tank and stick on your brute just to test and see if it corrects your issue? Ive had to do this with a couple buddies of mine more than once....lucky to have such good friends that are willing to tear their brutes apart just to help me find a problem on mine....and I've done the same for them a time or two lol.


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## zach93 (Jul 13, 2011)

Fuel pump is ordered. will be here late next week. Thanks for all the help. My dad and I really appreciate it.


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## filthyredneck (Feb 10, 2010)

No prob, glad we could help :bigok:


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## ernieb62 (Aug 12, 2011)

excellent job guys---that is why I am glad I found this forum extremely nice of all of you helping out with mechanical issues !!!!!


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## wyo58 (May 13, 2011)

When you replace that pump look in the tank with a flashlight and make certain the tank is pretty clean, or you will plug up that new pumps strainer right away!


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## zach93 (Jul 13, 2011)

for sure wyo58, we plan to run it dry with the old pump and clean the tank out good. Again thanks for all the help guys.


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## zach93 (Jul 13, 2011)

got the new pump in. The brute runs awesome. like new again. took it out today and got it up to 105 kph, last fall could only get 85 or 90 kph


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## filthyredneck (Feb 10, 2010)

Congrats


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## zach93 (Jul 13, 2011)

thanks again guys my brute is runnig like new awesome site.

Zach93's Dad


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## wyo58 (May 13, 2011)

Excellent!!!!!!!!!!!! glad we could help sorry you had to replace the pump with such an expensive one. Stay tuned on the pump replacement I'm about to zero in on one!


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