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Casey

Looses spark under load warm or cold.

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Hey everyone I've got an 01 Rubi and I pulled it out of the barn and it wouldn't start unless I sprayed carb cleaner in the carb, air filter was disgusting so I got a new one. I cleaned the carb once and it was still running like crap. Let it go for a little while. Went out a couple days later and wouldn't start at all so I checked the tank and it was nasty (dummy). So I took the carb off again and cleaned it and and cleaned the tank and put a fuel filter on it. Took it out for a ride and it still wasn't running good about mid throttle. You can putt along all day and its fine but if you get after it and ride at the next level it breaks up really bad. Its not so bad in neutral revving it up but pops still but under load its terrible. If you throttle through it it will catch and rev high. I thought it was fuel so I cleaned the carb again thinking I missed a passage way. I let it soak over night, put it back together and tried to ride it again and same thing! So I put my spark tester on it and its loosing spark randomly. It only seems to do it under load but will sputter if held at a constant RPM about mid range. Doesnt matter if you stab the throttle or try to slowly rev up to high RPM. I pulled every plug on the bike I could find and put dielectric grease on it and plugged them back in. I didnt check the TPS until after the third time the carb was off. It was around 4.7 which was low. So I pulled it off and tested it and couldn't find a spot that it would wig out. So I think its fine. I set it at like 5.05. I did the reset on the wheeler and heard the shift motor orient. Theres no codes. Is it possible that when soaking the carb I somehow fried the TPS? I tried to keep it out of the solvent as best as I could. I don't have a book but I checked the wires on the coil and the black has good ground but the Green is showing a very high resistance to ground. If I unplug it at the ECM its open. Is that normal to have continuity to ground on the power wire to the coil? Doesnt seem right to me. I was thinking the TPS but it seems to depend more on RPM than actual throttle position. Any one have a problem like this?! HELP! lol I'm getting quite the flat spot on my forehead from banging it on the wall trying to figure this thing out null

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Hi. Welcome to the site. 
 

thanks for providing all that info! If you wouldn’t have tested all that I would have guessed you mid range circuit still dirty, but I’m not familiar with that model quad. So be patient & someone here will be along to surely point u in right direction. If I’d make an educated guess off what u posted I’d lean towards a CDI.. but hang tight for the experts on this quad.. I’m just a 300 guy...

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welcome. 

 

you say pulled this as a barn find ? besides the tank, and air filter carb issues, were there any signs of rodents chewing on the wire harness, etc ? are you the original owner ? if not i would try and find out as much history on it as i could. 

 

here's a link to the service manual page. https://atvhonda.com/topic/92-service-manual-downloads/

 

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I said that but I’m working on it for a guy. He said he pulled it out of his shed and it wouldn’t start. Then I got it to fix. No wire damage I see. He thinks it was running fine before I put my hands on it and cleaned the carb. So I feel as tho I screwed something up. I put a new plug cap on it (Honda) thinking when I pulled it off I broke something. I cut about 3/8 of an inch of the wire off so it was fresh. 

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Glad you made it over here Casey and got your manual. I have the same machine and will look through my manual in a bit.

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Hi Casey, welcome to ATV Honda!

 

First things that I would do are:

  • Replace the spark plug with a new NGK. If it has a Champion plug in it it will act like you explained and eventually fail completely.
  • Remove and clean the battery ground cable where it bolts onto the motor and do the same with the frame ground.
  • Check the brake switch and diode.
  • Using a multimeter with Min/Max function or a Peak Voltage Adapter, measure the primary voltage at the coil. It should be 100 volts.

Let us know what you find out.

 

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Chapter 26 in the manual. Restricted fuel tank breaker looks like the easiest to check. Trying running with the cap off.

 

Edit: added another page section.

 

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Edited by Tim-ANC
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does it have a good battery? I didn’t see anything about installing a new one.

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I’m dealing with a similar issue on my 04 Rubicon 500...following this post and will update my own as well!

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