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Hey experts,

08 KFX 450R not starting. Put in new spark plug, new battery, and new fuel pump. I have the fuel pump out of the gas tank and connected and not hearing the prime. I have checked the orange fuses and they are good. Looking to get the fuel pump working...
 

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Hey experts,

08 KFX 450R not starting. Put in new spark plug, new battery, and new fuel pump. I have the fuel pump out of the gas tank and connected and not hearing the prime. I have checked the orange fuses and they are good. Looking to get the fuel pump working...
Welcome to the Forum...!!

Check the fuel pump relay for 12v on the W/R wire to frame ground...!! see picture attached

Also check the vehicle down sensor for falling off it's perch...see picture
 

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Discussion Starter #3
Welcome to the Forum...!!

Check the fuel pump relay for 12v on the W/R wire to frame ground...!! see picture attached

Also check the vehicle down sensor for falling off it's perch...see picture
Thank you Dust Devil! I did check the vehicle down sensor and it is still where it is supposed to be. Also checked the w/r wire from relay to frame ground. From the Relay it goes down to the Fuel Pump Assy (unless I am missing something).

Tested the fuel pump directly to battery and works fine. Seems like CDI malfunction not giving fuel pump power/load but no Indicator lights going off...
 

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Thank you Dust Devil! I did check the vehicle down sensor and it is still where it is supposed to be. Also checked the w/r wire from relay to frame ground. From the Relay it goes down to the Fuel Pump Assy (unless I am missing something).

Tested the fuel pump directly to battery and works fine. Seems like CDI malfunction not giving fuel pump power/load but no Indicator lights going off...
Thank you Dust Devil! I did check the vehicle down sensor and it is still where it is supposed to be. Also checked the w/r wire from relay to frame ground. From the Relay it goes down to the Fuel Pump Assy (unless I am missing something).

Tested the fuel pump directly to battery and works fine. Seems like CDI malfunction not giving fuel pump power/load but no Indicator lights going off...
The ECU doesn't diagnose it's self, just the sensors...!!

Before you purchase a new ECU...

Can you test the output voltage of the Vehicle down sensor...??
 

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Thank you Dust Devil! I did check the vehicle down sensor and it is still where it is supposed to be. Also checked the w/r wire from relay to frame ground. From the Relay it goes down to the Fuel Pump Assy (unless I am missing something).

Tested the fuel pump directly to battery and works fine. Seems like CDI malfunction not giving fuel pump power/load but no Indicator lights going off...
Check the ignition coil wire and boot. Mine was torn and corroded.
 

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The ECU doesn't diagnose it's self, just the sensors...!!

Before you purchase a new ECU...

Can you test the output voltage of the Vehicle down sensor...??
I checked and the voltage to the Vehicle Down Sensor was 4.98 volts. Does that sound right?
 

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I checked and the voltage to the Vehicle Down Sensor was 4.98 volts. Does that sound right?
Depends which wires did you hook to for that reading of 4.98v...Input voltage Yes. Meter (+) → LB lead Meter (–) → BR/BK lead
DC 4.75 ∼ 5.25 V
output voltage NO...see picture
Meter (+) → Y/G lead
Meter (–) → BR/BK lead
with sensor tilted 15 ∼ 35° or more right or left: 0.4 ∼ 1.4 V
with sensor arrow mark pointed up: 3.7 ∼ 4.4 V
 

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Depends which wires did you hook to for that reading of 4.98v...Input voltage Yes. Meter (+) → LB lead Meter (–) → BR/BK lead
DC 4.75 ∼ 5.25 V
output voltage NO...see picture
Meter (+) → Y/G lead
Meter (–) → BR/BK lead
with sensor tilted 15 ∼ 35° or more right or left: 0.4 ∼ 1.4 V
with sensor arrow mark pointed up: 3.7 ∼ 4.4 V
It took me a few days but checked all of this and readings are normal. So it is not the Vehicle Down Sensor... I guess.
 

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Got it. Would the ignition coil cause the fuel pump not to turn on? When I turn the key on, the fuel pump is still not doing anything like pressuring the line.
 

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Got it. Would the ignition coil cause the fuel pump not to turn on? When I turn the key on, the fuel pump is still not doing anything like pressuring the line.
Yes...The power for the ignition coil & fuel pump relay is the Y/R wire @ the handle bar, (headlight, start/stop & starter button)...So check there for corrosion & bad connection...
Also follow the wires from the handle bar light switch/starter button to where they plug into the main wiring harness under the hood, sometimes it comes loose...!!!

See #2 in the fuel pump diagram below
 

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Yes...The power for the ignition coil & fuel pump relay is the Y/R wire @ the handle bar, (headlight, start/stop & starter button)...So check there for corrosion & bad connection...
Also follow the wires from the handle bar light switch/starter button to where they plug into the main wiring harness under the hood, sometimes it comes loose...!!!

See #2 in the fuel pump diagram below
Checked the spark plug and I am not seeing a spark. I replaced the spark plug and still don't see a spark. Assuming something wrong with the coil. I will check the wires as instructed as well and report back.
 

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Yes...The power for the ignition coil & fuel pump relay is the Y/R wire @ the handle bar, (headlight, start/stop & starter button)...So check there for corrosion & bad connection...
Also follow the wires from the handle bar light switch/starter button to where they plug into the main wiring harness under the hood, sometimes it comes loose...!!!

See #2 in the fuel pump diagram below
Checked the wires as instructed and no corrosion and all connections look good... I guess I am down to the coil and still possibly ECU?
 

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Quick question...Does your kfx have a tether kill switch by chance, ..see picture

Lights working means good negative/grounding...

The ECU might be bad..No negative pulse for the ignition coil or fuel injector..
No, bike does not have a tether kill switch. Does that rule it down to bad ECU?
 

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No, bike does not have a tether kill switch. Does that rule it down to bad ECU?
maybe it's a bad ECU...But..? It could be the crank sensor...?

Can you test the crank sensor...? see picture

To test the crank sensor you'll need an analog Voltmeter (see picture)...Digital meter will not work..
 

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maybe it's a bad ECU...But..? It could be the crank sensor...?

Can you test the crank sensor...? see picture

To test the crank sensor you'll need an analog Voltmeter (see picture)...Digital meter will not work..
Do you have a picture of the crank sensor? I also was inspecting wire near the front and found this brown wire just hanging there. Do you know what this is for?
28249
 

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Do you have a picture of the crank sensor? I also was inspecting wire near the front and found this brown wire just hanging there. Do you know what this is for?
Brown wire on the wiring schematic is power (wiring schematic)... since you have power, It might be for an accessory on the European model with the style of connector on the end of it..!

As for the crank sensor...see the 2 prong connector with Blue/yellow & white wire connecting into the red & yellow wire see picture below

You'll need to set the analog multimeter to 10v ac or lower & connect the meter's leads into the Blue/yellow (-) & white (+) wire and crank the motor & watch the needle bounce to the 2v or higher measurement on the meter...
 

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