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...
08 Brute trouble
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?
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?
1 - 20 of 39 Posts
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...
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...
Yeah I agree with the others any other mods?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?
First thing I would check is fuel pump! Sounds like the 1/3 throttle sputter
we need to know all the mods he has on it...i was just guessing on the first post
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.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.
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
.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
Attachments
-
71.1 KB Views: 235 -
74.9 KB Views: 233 -
88 KB Views: 599
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.
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
:agreed:
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
:agreed: I would at least check the strainer if your flow test does not come out good.
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
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.
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?
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.
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.
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.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
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.
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?
1 - 20 of 39 Posts
- This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Mud in My Blood Forum
A forum community dedicated to Off Road Powersport owners and enthusiasts. Come join the discussion about performance, reviews, classifieds, troubleshooting, maintenance, and more! Open to anything that slings mud Including Yamaha, Honda, Kawasaki, and Suzuki.
Full Forum Listing
Explore Our Forums
Recommended Communities
