2018 Kawi kxf250 running bad/popping

NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/19/2019 6:54am Edited Date/Time 9/25/2019 4:24am
Posting for a friend. Bike ran fine all day at the track. Next day bike was started on the stand was running fine for a minute then all of a sudden started running poorly and popping/backfiring. Bike was never washed and still had same fuel from day before. He changed plug and no help. He brought the bike to my home shop, I disconnect the fuel line from tank, connect a long rubber hose to a bucket and kicked over the bike, no fuel would pump out. I pulled the tank and ran direct 12v and the pump ran and pumped fuel no problem, connected a gauge and would get about 45 psi. I did noticed when the pump wasn't running a small amount of fuel would still gravity flow and I always thought no fuel should flow out the tank/pump when the pump wasn't running. I'll get back to this later. Put the tank back on the bike and the bike started and ran fine for about 30 seconds then started to cut out and pop again. Next was disconnect fuel pump wires and as the bike is being kicked over the voltage will start rising and get up to about 9-10 volts. Is this not enough voltage possibly? Re started bike and same thing, just to get the bike started fuel needs to be dripped into T/B and once running its doing the same thing. Since I noticed some fuel will gravity feed, I"m wondering if its just getting enough fuel gravity flowing through the injector "if that's even possible" to run but not enough causing it to be lean and pop and back fire?? Double checked cam timing, dead on. Next thing I'll try is to run direct 12 volts to fuel pump and see what happens. If it happens to run fine this way what could be causing the fuel pump not to stay running while on the bike?? Bad voltage regulator, bad condenser? Has anyone had a kxf250 run poorly and figure out the issue? Does anyone know what the tip over sensor shuts off if it is bad? Trying to get a service manual from another guy to help troubleshoot. These bike can be frustrating lol
|
kb228
Posts
6161
Joined
1/31/2018
Location
Mansfield, OH US
8/19/2019 8:18am
The fuel pump isnt supposed to drip at the nipple. I will add that my kx450 DOES drip, and it runs completely fine, although its not supposed to do that.

To me it seems like its starving for gas. Id replace or clean the injector and see if it gets better. Replace the fuel pump afterwards.
Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
8/19/2019 10:12am
That low voltage is an issue that will need to be addressed.

Paw Paw
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/19/2019 10:28am
That low voltage is an issue that will need to be addressed.

Paw Paw
Thanks guys, I'll first try 12 volts direct to pump and if the bike runs fine I guess I'll start working backwards.
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/19/2019 10:49am
I don't have a wire schematic yet but does anyone off hand know what the tip over sensor activates or deactivates?

The Shop

kb228
Posts
6161
Joined
1/31/2018
Location
Mansfield, OH US
8/19/2019 1:02pm
Tip over sensor will kill the bike after 3 seconds if its installed upside down or broken. Its not your problem
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/19/2019 2:45pm
kb228 wrote:
Tip over sensor will kill the bike after 3 seconds if its installed upside down or broken. Its not your problem
I understand what it does by shutting down the engine from a tip over protecting it from burning up from lack of oil or something. I want to know how it does it. Do it shut off fuel or spark through ECU? Just want a better understanding how it works. I have heard people having issues with them, bike either not starting or runnng bad.
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/19/2019 3:35pm
Well I just connected 12volts from a small battery directly to fuel pump wires and the bike starts up and runs perfect. Plug it back into the bike harness and same issue, bike will not start. The connection looks to be good. Something is stopping the fuel pump to energize. Could be condenser, voltage regulator, ECU itself or even stator. No the fun begins. Any suggestions feel free. Lol
Paul_Pitzonka
Posts
693
Joined
5/1/2018
Location
Grand Terrace, CA US
8/19/2019 3:51pm
First thing I’d disconnect is the capacitor and run a 12v battery in its place this allows you to put the bike into a diagnostic mode to rule out anything simple...
3
Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
8/19/2019 5:08pm
Now that is some good info there!

Paw Paw
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/19/2019 5:31pm
First thing I’d disconnect is the capacitor and run a 12v battery in its place this allows you to put the bike into a diagnostic mode...
First thing I’d disconnect is the capacitor and run a 12v battery in its place this allows you to put the bike into a diagnostic mode to rule out anything simple...
Yes good info and thanks. Will try and run this diagnostic tomorrow. Earlier when I got the bike running with fuel pump wires disconnected and running a battery directly to pump I was getting 13 volts from the frame harness that connects to fuel pump wires while the bike was running. Just kicking it over I’m only getting 6-7 volts and the pump will not pump fuel from a hose into a bucket. I’m getting close just need to narrow down the problem. The info above should help a lot. Thank you!! Question, if it’s even possible if I replace the capacitor with a battery wired in and the bikes start and runs fine would it directly say the capacitor is bad? I’m just asking because I’m not sure if it works that way and I know your saying it’s for diagnostic purposes.
Paul_Pitzonka
Posts
693
Joined
5/1/2018
Location
Grand Terrace, CA US
8/19/2019 7:09pm Edited Date/Time 8/19/2019 10:49pm
First thing I’d disconnect is the capacitor and run a 12v battery in its place this allows you to put the bike into a diagnostic mode...
First thing I’d disconnect is the capacitor and run a 12v battery in its place this allows you to put the bike into a diagnostic mode to rule out anything simple...
Yes good info and thanks. Will try and run this diagnostic tomorrow. Earlier when I got the bike running with fuel pump wires disconnected and running...
Yes good info and thanks. Will try and run this diagnostic tomorrow. Earlier when I got the bike running with fuel pump wires disconnected and running a battery directly to pump I was getting 13 volts from the frame harness that connects to fuel pump wires while the bike was running. Just kicking it over I’m only getting 6-7 volts and the pump will not pump fuel from a hose into a bucket. I’m getting close just need to narrow down the problem. The info above should help a lot. Thank you!! Question, if it’s even possible if I replace the capacitor with a battery wired in and the bikes start and runs fine would it directly say the capacitor is bad? I’m just asking because I’m not sure if it works that way and I know your saying it’s for diagnostic purposes.
If it starts and runs fine with the capacitor replaced by a battery that would be lead me to believe it’s either an issue with the capacitor, stator, or regulator/ rectifier... sorry I can’t narrow it down further, but all three can lead to your problem and replacing the capacitor with an inline battery won’t tell you directly what’s wrong it just narrows down your possibilities...
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
8/23/2019 7:16pm
Update-the owner tried a new capacitor and didn’t fix the issue. Next step will be to try and swap out the regulator from another 18 that one of his friends has, if no luck he will try the stator. Hopefully the regulator does it. I’ll get back and post up
NoMuff2Tuff
Posts
192
Joined
2/11/2015
Location
La Place, LA US
9/25/2019 4:24am
The problem ended up being the stator. Even though the bike would run fine using 12 volts from a battery directly to the fuel pump and still show 12 volts from the from the in coming fuel pump wires while the bike was running. It doesn’t make sense at all but the bike fired right up using a loaner stator from another bike. The only thing I can think is low amps came into place and it didn’t have enough amps to actually run the fuel pump even though the meter showed 12 volts. When you are trouble shooting an electrical issue or if a bike is not running well never rule out anything and it makes things much easier when you have another bike to swap parts. Thank you again for all the replies!!

Post a reply to: 2018 Kawi kxf250 running bad/popping

The Latest