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Discussion Starter #1
Okay guys, I got my Kfx a while back and I'm pretty much new to these ATVs. So back to the problem I would be going and the KFX would be running fine but when I hit 75-100% throttle it would miss and sputter really, really bad. And me and my brother was trying to fix it and we seen a website with a guide on how to see what is wrong with the F.I. so we run a wire to the battery and hooked it in the F.I. light which must of been the wrong place and shorted something out now the lights won't work and the fuel pump won't even kick on, plus it won't crank. :confused::confused::confused:
 

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Check the main fuse at the starter relay, located on the left hand side of the steering stem under the hood.
 

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Well, I'll check tomorrow but do you know what the 75-100% throttle miss would be?
Does the f.I light remain on or flashing when idling...?

TPS voltage out of range, bad/fouling spark plug, bad spark plug cap, carbon build up, loose ground or fuel pump going bad...

Check the TPS voltage...0.58~0.62 volts @ close 3.7~4.1 volts @ WOT...see pic..


Fuel pump is 43 psi constant from 1800~10,000 RPMs...
 

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Does it have an aftermarket intake? Sounds like it needs a programmer.
 

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Discussion Starter #7
I think I've figured it out guys, since it won't crank it pretty much has to be a bad fuse, and also Dust Devil I believe its the TPS is bad because I'd notice idle changes and it would Idle to fast. But, do you guys know what the thing you check the TPS voltage is called, LOL
 

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I think I've figured it out guys, since it won't crank it pretty much has to be a bad fuse, and also Dust Devil I believe its the TPS is bad because I'd notice idle changes and it would Idle to fast. But, do you guys know what the thing you check the TPS voltage is called, LOL
Easiest is the sensor adapter part# 57001-1538 to test the TPS voltage with...57001-1538 SENSOR ADAPTER $17.35
Or
Stick paper clips into the back of the connector and use alligator clips on your meter leads...

With erratic idle
Make sure your throttle body clamps on the boot are tight and check the air pressure sensors vacuum hose for cranks or splits...
 

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I bet the problem with 75-100% throttle response feeling boggy is your fuel strainer and filter in the pump that need back flushed(which is a little easier than opening up the pump housing and re plastic welding it Back together) IMO. Think about it its been on there since 2008 and its only a little roughly 1 1/2 by 1 1/2 -2 inch strainer. I believe you can use the Brute force fuel pump strainer its the same one. Or you can make the part number fs205 from advanced auto work. I had those symptoms so just my 2c. Good luck
 

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I took the fuel pump off it all looked clean.
The only way to test the fuel pump is with a tester, 43 psi constant 1800~10,000 RPMs, this kind...New Fuel Injection Pump Injector Tester Test Pressure Gauge Gasoline Cars Trucks | eBay

Make sure your throttle body clamp are tight so there's no air leaks...

Check your compression if it's high you have carbon build up on the piston, Seafoam motor treatment will clear it up....Sea Foam Auto Marine Motor Tune Up Treatment for Diesel and Gas Engines SF16 | eBay

They also sell it at K-Mart & autozone...!
 

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Discussion Starter #14
Alright got it back running Dust but theres still like a bogg down at 75-100% throttle and now the fan isn't kicking on but I checked the fuse, it was fine. We cleaned the filter the other day and we used a little gas and the bogg down went away until it sucked all the gas out of the filter.
 

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Alright got it back running Dust but theres still like a bogg down at 75-100% throttle and now the fan isn't kicking on but I checked the fuse, it was fine. We cleaned the filter the other day and we used a little gas and the bogg down went away until it sucked all the gas out of the filter.
The fan normally comes on at motor temps of 160~180 degrees..

To test the fan...!
Dis-connect the water temp sensor located on the back of the cylinder under the throttle body, turn the key on, the F.I dash light should remain on and your fan should come on...!
 

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The fan kicked on, I guess I didn't give it enough time
Ok! If the TPS voltage is in range...see pic

The bogging issue is usually the fuel pump going bad or it's the strainer clogging bet to replace the strainer unless it's the pump pressure regulator...

"tea bag" fuel filter / strainer
KVF750 Brute Force 750 if you look under 2013 parts diagram the part number is 49019-0013. $12-$13 will work with the kFX450 fuel pump...
 

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