Posts: 25
Joined: 3/9/2015
Location: Childress, TX USA
I have a 2009 CRF450 that started having a running issue halfway through my ride the other day. The bike runs amazing on the gas, as soon as I let off it completely goes dead. I suspected a fuel pump, put in a new one and I have the same issue. The bike runs great at all other rpm and will idle if I slowly back off the throttle. I have no clue where to start! Valves are in spec, compression is good, everything has been great until this issue.
Posts: 25
Joined: 3/9/2015
Location: Childress, TX USA
Posts: 5832
Joined: 1/31/2018
Location: Mansfield, OH USA
Is your idle set to what your manual says? Theyll do that if its too low. Also tps could be off at closed throttle.
Posts: 25
Joined: 3/9/2015
Location: Childress, TX USA
Yes I’ve played with the idle a lot, if I set it absurdally high it will keep it going. I unfortunately don’t have a setup to test the TPS, seems odd that it would get out of wack halfway through a ride though. I’m considering the ECU as a possible cause.
Posts: 2300
Joined: 3/18/2016
Location: CA, USA
Edited Date/Time:
Have you tried a new fuel filter ? Also suggest cleaning all the electrical connections as that could be a possible culprit.
Speak softly and carry a big stick.
Posts: 5832
Joined: 1/31/2018
Location: Mansfield, OH USA
Ive seen TPS sensors vibrate out of adjustment. Dont rule it out. Checking it is a lot cheaper than dumping money on an ecu when it could be any one of your sensors.
Posts: 3609
Joined: 4/3/2013
Location: Benton, LA USA
I suspect low fuel pressure from bad fuel pump or plugged filter or dirty fuel injector.
Have you changed the cam chain?
Is the valve timing 100% correct?
Cam gear slipped on camshaft?
TPS adjustment?
Paw Paw
