[amp625]

Long story short I bought a 09 Honda CRF450 dirt bike that was not running. Upon inspection found one bent exhaust valve. I replaced the valve/guide as well as a fresh set of rings while I was in there. Bike would not kick start. Performed cylinder leak down test, verified timing, as well as valve clearance and all were perfect. Compression is great.

I knew the 09s had common fuel pump filter clogging issues. Found someone removed the fuel filter at some point, so put one on. Pump had been running unfiltered fuel. Verified fuel pump runs by disconnected the condenser and applied 12V from a lawn mower battery to connector and could hear pump run. Supply pressure unknown as I do not have a fuel press. tester for this setup. Verified Fuel spraying out of injector by disconnecting throttle body and kicking bike over. Also verified spark when kicking bike over.

At this point the engine had no reason not to run. I had my friend pull me behind his truck and bump started bike. Bike started right up, quickly got on throttle and ran through the gears, had plenty of power, ran for about 30 seconds, and died while i was on the throttle. Quickly bump started again while I was still rolling and it started back up. This time ran for about 10 more seconds and died at cruising speeds. the engine does not bog down and die like its losing fuel pressure. It just quits.

I have bump started it two weekends in a row with similar results. Runs for less than a minute in total and just dies. Bike will not idle. Must be constantly supplying throttle to keep the bike running.

So the main issues at hand are it will not kick start and it will not idle/stay running.

There are no diagnostic trouble codes stored in the system.

Fuel supply issue or issue with heat? I'm not too sure

Possibilities I'm thinking of are fuel pump having an intermittent internal failure, high resistance of stator when warm not supplying adequate voltage, or a possible ECU fault?

Spark plug is new, air filter is removed for testing purposes. Spark plug gap is also set.

Any input would be much appreciated.

[JimDirt]

You already have a post on this topic ........ We pretty well went over the possibilities , which is leading to ECU as most likely cause (not 100% , but given the other things listed is the most likely) , Something else we are missing ?? confused

Link to post:
https://www.crfsonly.com/forum/viewtopi ... =2&t=45800

[amp625]

You already have a post on this topic ........ We pretty well went over the possibilities , which is leading to ECU as most likely cause (not 100% , but given the other things listed is the most likely) , Something else we are missing ?? confused

Link to post:
https://www.crfsonly.com/forum/viewtopi ... =2&t=45800

Sorry for the repost. I initially thought there was a fuel delivery issue "first post" now I think it is something else. I have replaced fuel pump and filter, disconnected throttle body and kicked bike over to verify fuel spraying, and cleaned injector and monitored spray pattern. Also have triple checked spark. Even cut the ground strap off of a "test" spark plug and kicked it to verify enough "spark" to jump the gap.

Also hooked DVOM to fuel pump connector. Had approx. 7V DC present at fuel pump when kicking bike over. Seems sufficient. I am at a loss. Bike will not even fire on starting fluid. But you bump start it and it runs as designed for 30 seconds or less. Spark plug is new, air filter is removed. Compression, timing, valve clearance all great.

Disconnected the condenser as well and applied 12V from battery after replacing fuel pump just to verify that it powers on, which it does.

[amp625]

To add one more thing. When bump starting i need to give it about half throttle for it to start and needs constant throttle to stay running. I have tried giving it throttle when kicking it will no luck, not even a fire. Also have checked the idle adjustment to ensure that wasnt screwed all the way in.

[JimDirt]

Go over these specs and test , to eliminate the fuel system ...





If nothing comes of this , then we can move on to ECM and Stator testing .....

I can post whatever info is needed from my Factory Service Manual here , for you to go over ....

[amp625]

So resistance tested the sensors and everything was in spec. Applied 12V from an atv battery to recheck for codes. Light on killswitch did not even flash. I unplugged battery and disconnected MAP sensor just to see if kill switch would blink a code. Nothing. I know the kill switch was blinking a couple weeks ago, I had a code for the MAP and replaced it. I removed the wiring harness and thoroughly went through each individual wire ensuring continuity and no issues to report.

[JimDirt]

So you replaced the MAP switch and now you get nothing as far as blinks go , and all connections (to everything I am assuming) tested good ??

[amp625]

Yes all sensors within spec. When I first started working on the bike I had 7 blinks (I think) which correlated to MAP sensor failure. Replaced MAP and that's when I was able to run the bike for 30 seconds or so. The other day when I hooked up 12V to the condenser pigtail I was told the LED should flash. No flash but fuel pump was running. So I disconnected the MAP to see if any LED would flash. Nothing. Leading me to believe there is an issue with ECU or the LED on kill switch.

The Kill switch is a 4 wire connector. Do you happen to know which wire is power/ground for the LED? Will use a power probe and test to ensure the light works.

[JimDirt]

Here is the wiring diagram to help you trace everything

[amp625]

Hey Jim,

I am still dealing with this no start issue. Just took a break from it. Went over everything today and now have no spark. I'm certain it had spark a month or so ago, but whatever.  Ignition coil primary resistance within spec as well as the stator static resistance per the Honda Shop Manual. I have swapped with a known good ECU as well. Also tested the kill switch resistance when pushing button and everything seemed to work there. 

I then disconnected the throttle body and kicked the bike over to verify fuel was spraying. Fuel did in fact spray. My question for you, is the injector timed off the CKP sensors as well? Does the fact that fuel is spraying verify CPK/Stator operating as designed? 

I ran through most of the pinpoint testing found in section 17 "Electrical Systems" of the manual. However, I was unable to test for peak voltage due to not having the peak voltage adapter. 

[amp625]

Let me add that yes I have tried disconnecting the fuel pump with no change as well as disconnecting the condenser and applying 12V DC. Still no spark. Thanks

[Aussiecrf230]

Did someone say Peak Voltage Adapter

https://www.crfsonly.com/forum/viewtopi ... 32&t=44830

[Roy16861]

Good afternoon gents .. I have a 2016 crf 250 r kick start model.. I've tried without any luck to start the bike fires but wont run .. give the bike a push start off she goes runs good .. any idea what the problem is ? Cheers