2008 BF750i Starting Problem

[JAM750BF]

My BF750i has been acting up lately. For some reason it won’t start without using the throttle and then sometimes it won’t start at all.

It has been at my dealer twice and we can’t come up with the issue. They checked the fuel pump and it working correctly. In fact it may be working too good, supposedly the manual says it should push 50 milliliters to start, but it is registering around 100 milliliters when you first turn on the key.

The last time at the dealer, they changed the plugs but that only seemed to fix the problem briefly.

Could the fuel pump be pushing too much fuel?

Does anyone have any advice here as what may be causing this…I have searched all the sites I know to find an answer, but no help so far?

Thanks
JAM

[NMKAWIERIDER]

Originally Posted by JAM750BF

My BF750i has been acting up lately. For some reason it won’t start without using the throttle and then sometimes it won’t start at all.

It has been at my dealer twice and we can’t come up with the issue. They checked the fuel pump and it working correctly. In fact it may be working too good, supposedly the manual says it should push 50 milliliters to start, but it is registering around 100 milliliters when you first turn on the key.

The last time at the dealer, they changed the plugs but that only seemed to fix the problem briefly.

Could the fuel pump be pushing too much fuel?

Does anyone have any advice here as what may be causing this…I have searched all the sites I know to find an answer, but no help so far?

Thanks
JAM

With fuel injection it isn't so much volumn of fuel, its pressure.The computer just tells the injectors when to pulse and for how long at certian RPMs. This is in the maping. If the pressure to the injector is too low, it may not despence enough fuel if any. As for starting with the throttle, you are just moving the butterfly in the throttle body. This would change the air mixture on the starting cycle which is one thing I thing they say not to do with injected machines. But this might say there is somthing wrong with the controler or the ecu. A blast of air will also make it easier for a weak spark to jump and detinate the fuel. You might have weak power to the coils. Pull the front plug, slip it back on to the wire, lay the body or metel part against the engine so you can see the spark when you crank it over. Then do so and watch it. It should be near as solid as the center probe and blue as can be. Of its redish and so small you can't hardly see it, something is worng with the ingition system. Please do check your valve settings. People don't do this often enough. Leaky valves make for lower compression which makes engines start harder too. Good luck.

[bustamove]

i have been having to give my brute gas for a long time.. i just tap the gas when its starting.. or eles if cold i willl hit the starter and it will crank over like 4 to 5 times sometimes catch sometimes not... but on the second start its starts for sure.

not saying its right... but for the most part it runs fine.

does these bike have a fuel regulator? also usually i hear about fuel pump failures. i would check a major sensor that the computer uses to figure out how much fuel to put in..

[NMKAWIERIDER]

Originally Posted by bustamove

i have been having to give my brute gas for a long time.. i just tap the gas when its starting.. or eles if cold i willl hit the starter and it will crank over like 4 to 5 times sometimes catch sometimes not... but on the second start its starts for sure.

not saying its right... but for the most part it runs fine.

does these bike have a fuel regulator? also usually i hear about fuel pump failures. i would check a major sensor that the computer uses to figure out how much fuel to put in..

And..although they don't have an 02 sensor, ther have to have a TPS (Throttle Position Sensor). Those tell the computer where the throttle body's position is at any given time. If that is off, and I have seen cars with this, the computer doesn't pulse the injector long enough to give it enough fuel to start sometimes. That might be why when you tic it up a bit it does start. That's the only sensor that is effected by opening the throttle. You guys should try to start them with just the smallest amout of throttle on...like almost nothing and hold it there..not moving it while on the starter. If it starts..bingo..TPS adjustment needed.

[JAM750BF]

Originally Posted by NMKAWIERIDER

With fuel injection it isn't so much volumn of fuel, its pressure.The computer just tells the injectors when to pulse and for how long at certian RPMs. This is in the maping. If the pressure to the injector is too low, it may not despence enough fuel if any. As for starting with the throttle, you are just moving the butterfly in the throttle body. This would change the air mixture on the starting cycle which is one thing I thing they say not to do with injected machines. But this might say there is somthing wrong with the controler or the ecu. A blast of air will also make it easier for a weak spark to jump and detinate the fuel. You might have weak power to the coils. Pull the front plug, slip it back on to the wire, lay the body or metel part against the engine so you can see the spark when you crank it over. Then do so and watch it. It should be near as solid as the center probe and blue as can be. Of its redish and so small you can't hardly see it, something is worng with the ingition system. Please do check your valve settings. People don't do this often enough. Leaky valves make for lower compression which makes engines start harder too. Good luck.

wow...you said a ton here, i will print this and take it to the tech...which i am not! I hope it's nothing major...I sold my POLARIS 800 for a more reliable machine, and so far that has not been the case.

Thanks and keep the suggestions coming.

[bustamove]

Originally Posted by NMKAWIERIDER

And..although they don't have an 02 sensor, ther have to have a TPS (Throttle Position Sensor). Those tell the computer where the throttle body's position is at any given time. If that is off, and I have seen cars with this, the computer doesn't pulse the injector long enough to give it enough fuel to start sometimes. That might be why when you tic it up a bit it does start. That's the only sensor that is effected by opening the throttle. You guys should try to start them with just the smallest amout of throttle on...like almost nothing and hold it there..not moving it while on the starter. If it starts..bingo..TPS adjustment needed.

there is also an idle air control valve in there aswell as temperature sensor, coolant sensor, air pressure. you guys thought your carbed bike had problems... EFI i like a deck of cards take a leg out and the system goes FUBAR.

[bustamove]

Originally Posted by JAM750BF

wow...you said a ton here, i will print this and take it to the tech...which i am not! I hope it's nothing major...I sold my POLARIS 800 for a more reliable machine, and so far that has not been the case.

Thanks and keep the suggestions coming.

its not that kawie isn't reliable but do require alot of maintenance, its alot like dating a super model, lots of maintenance and bull crap but she will put a smile on your face every time.

its hurts me to say this but if you want really reliable honda are the way to go, i suggest them to hunters and oldler guys...

[NMKAWIERIDER]

Originally Posted by bustamove

its not that kawie isn't reliable but do require alot of maintenance, its alot like dating a super model, lots of maintenance and bull crap but she will put a smile on your face every time.

its hurts me to say this but if you want really reliable honda are the way to go, i suggest them to hunters and oldler guys...

That's saying it. If you want to just get you there and back, and you don't have any real mountains to climb, then Honda will always do the trick...being an old Honda Man as I am. But, nothing will get your heart rate up and take you closer to the edge of loosing control like a Kawie..or a super model.

[Coolwizard]

Originally Posted by NMKAWIERIDER

That's saying it. If you want to just get you there and back, and you don't have any real mountains to climb, then Honda will always do the trick...being an old Honda Man as I am. But, nothing will get your heart rate up and take you closer to the edge of loosing control like a Kawie..or a super model.

I agree, my FIL has a 2000 rancher that has been beat, used, and abused. It's sits outside in the weather year round. I seriously doubt if has had the oil changed more than twice but it starts and runs like a timex watch everytime. It's the most reliable machine I've ever seen.......but it definitely aint no Brute!

[JAM750BF]

Funny you should mention HONDA, you should have seen my 11 year old on his HONDA 250 TRX pulling the Brute over 2 miles the last time it would not start while out riding.