2009 CRF450 running issue, HELP!

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10/6/2018 12:41 PM

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.

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10/6/2018 12:43 PM

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10/6/2018 4:25 PM

Is your idle set to what your manual says? Theyll do that if its too low. Also tps could be off at closed throttle.

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10/6/2018 5:09 PM

kb228 wrote:

Is your idle set to what your manual says? Theyll do that if its too low. Also tps could be off at closed throttle.

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.

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10/6/2018 5:28 PM
Edited Date/Time: 10/6/2018 5:30 PM

Have you tried a new fuel filter ? Also suggest cleaning all the electrical connections as that could be a possible culprit.

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Speak softly and carry a big stick.

10/6/2018 6:33 PM

kb228 wrote:

Is your idle set to what your manual says? Theyll do that if its too low. Also tps could be off at closed throttle.

bowens971 wrote:

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.

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.

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10/6/2018 8:10 PM

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

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