UXV 500I Boggs when throttle applied, wont go over 6 MPH or 3500 RPM

[J.Carter]

  Hi guy's,  New user here & Thanks for having me as well!  I work on small engines occasionally & even get lucky sometimes on fixing them lol

Ok a neighbor bought a UXV 500I (Fuel Injected no carb) 2012 model year as far as I can tell. 3350 miles on it, 893 hours.  Its was non running for at least a year & kinda rough shape but not totally scrap worthy.

Got it to the yard, & started trouble shooting the vehicle for him.  Previous owner stated he had changed the fuel pump (Ne did not), ignition coil, & plug.  No joy there so he sold it.  He had removed the exhaust & also sold the front bumper w/ winch.   I wondered it it was a clogged exhaust issue being he removed it.

I drained the tank of old fuel & was able to jump it & finally get it started but it ran like pure garbage. Got it warm enough to do an oil & filter change at the least. Now the oil has been changed twice just for good measure.    Figured the valves needed an adjustment so I removed the cover & they were tight.  The intake cam is a bit rough like it was soft & or  starved for oil at some point - that's a bad sign I know.  Set the lash at 0.004 on both TDC.  That helped some but not much. tried setting them just a bit more in either direction to see the the difference.  It did help with cranking but I went back to 0.004 as that seems to be recommended.   Tried the exhaust both on & off the thing - no real difference   

Its very hard to start sometimes & sometimes not so bad - the starter is loud but functional.

Fuel pump was the original so I got him to order a replacement knockoff  for a MULE & worked it into the tank as you can find on youtube.   That helped.   The coil was actually changed - he didn't embellish that part.  The plug sometimes comes out dark & really Soot covered.  Running rich & the stock plug sometimes loses fire & I use a smaller plug from my china 4 wheeler & it runs fine  go figure. 
   Put a new battery in it & that really helped with the two codes - they are gone now.  it was showing two codes  to do with Charging & I forget what else but I got them cleared up.    The check engine light is on at startup still.  Goes away once started.
     The switch is a bit worn but functional, the starter is loud & sometimes takes a few seconds to fire the vehicle up.    It idles well enough, climbs hills etc in low or high but will not go above 6 MPH in High on flat ground. It wont go over 3500 RPM either.  sometimes it will do 11MPH tops downhill.  It Drinks fuel like nothing Ive ever seen so that leads me to think its a TPS issue or something similar.  Seems like something is holding it back - tried the air filter & cover both on & off  no real diff.

I think that's all the issues,  Sorry for the jumble here & any ideas before I start buying sensors etc?

[Stig / Major Tom]

Welcome to the forum!
I know squat about UXV's so I'll stay out of this - help should be along ....

Good luck

Stig

[J.Carter]

Welcome to the forum!
I know squat about UXV's so I'll stay out of this - help should be along ....

Good luck

Stig

Thank you Sir, I understand its a long shot & I'm probably forgetting a lot of info that needs to be said also but it's worth a shot to see if someone out there has any fresh ideas on the strange issue here.        Its something small im sure, I pulled the belt cover off & it looks good for its age so thats another possible problem crossed off the list.

  I'll keep at it & maybe get some luck

[Bratman2]

Probably not your problem being it is drinking fuel, but I will throw this out there just in case. My 19 UVX 700 will not go over 7-8 mph unless my driver's seat belt is fastened. Could it be a bad switch in the seat belt? Are you are using the belt?

[J.Carter]

Probably not your problem being it is drinking fuel, but I will throw this out there just in case. My 19 UVX 700 will not go over 7-8 mph unless my driver's seat belt is fastened. Could it be a bad switch in the seat belt? Are you are using the belt?

I had read about that I don't see any sensors going to this one Seat belt wise but I'll give it a try.

Edit, this earlier model doesn't have that feature,  I appreciate the try at it though sir!!

I did remove all the sensors & clean them, no luck there either.  Just seems something small is holding it back from its full potential...

[CROSSBOLT]

Gobbling fuel may be injector pattern is so crappy that it is solid stream instead of fine spray. You mat want to observe spray pattern during start sequence. Should be a fine mist. Any streaming  send the injector to a shop for check and clean/repair.

Try Injector Master in Portland, OR...25 bucks and 24 hour turn around if no reliable shops in your area.

[J.Carter]

Gobbling fuel may be injector pattern is so crappy that it is solid stream instead of fine spray. You mat want to observe spray pattern during start sequence. Should be a fine mist. Any streaming  send the injector to a shop for check and clean/repair.

Try Injector Master in Portland, OR...25 bucks and 24 hour turn around if no reliable shops in your area.

I did pull the injector, lightly cleaned & it blasts out a fine mist as you'd expect.  I'll recheck anyway just to be dead sure.  This is driving me nuts LOL.

[J.Carter]

  I ordered a new belt, maybe that will help as this one is at about the service minimum (its 1.25").

Ill post tomorrow when it comes in & I figure out how to remove the drives with the special tools.

I'll also inspect the clutch & drives for common worn parts (rollers, springs etc).
 
 Wish me luck...

[J.Carter]

  Well I got the new belt along with brake pads yesterday.
Picked up a G-Force belt & installed it along with an inspection of the drives etc.  Everything looks good, one slightly cracked roller but they all measure well within spec.  No real change, but it does feel a bit stronger uphill.      Its gotta be electrical or the wear to the intake cam lobe is all I have left to go on.
    Back to the drawing board I guess.

[J.Carter]

  Alright, for anyone in the future having a similar problem here's my findings.

I tried the new G-Force belt, it only helped via the placebo effect. Glad to have a new one on nonetheless. Cleaned & inspected both drives, they were dirty & so were their ventilation system ( the plastic tube).  The rollers were decent condition, only one had a crack in the side. Otherwise they all were still above minimum spec so I haven't replaced them yet.
     
  I ordered a new intake camshaft & got it yesterday.  Installed it & set the lash to .004 IN & EX. polished the rocker also.

    That was the ticket, she runs fine now.     Will report back if any issues arise.

[CROSSBOLT]

Cam bad or out of time? Both?

[J.Carter]

  Good question sir, the Cam lobe was almost nonexistent on the intake camshaft.  I had noticed it showed some ware when the machine first got into my hands but figured I'd tackle all the electrical problems/codes etc  first.    I was honestly just avoiding a big problem & should have tackled it first off but wasn't sure the machine would survive me lol.     The original owner was hard on this thing & it shows but she is looking & running much better now. 

[J.Carter]

Cam bad or out of time? Both?

   

                              TLDR - It was Both

   Just a follow up in case it helps anyone in the future with this problem.

  Today was windy & miserable so I figured who not stand out in the cold & tear my machine down again.

I had noticed the New replacement intake cam had worn down just like the original had, so I ordered a used one this time that I figured must be properly hardened as it lived one life already.  Long shot I know.  I replaced it & added a new rocker also this time.  After replacing both & setting the lash to 0.004 it still just crept along at 6mph & bogged when throttle was applied beyond say 15%.
      I bit the bullet, took the valve cover & timing hole cover off & removed the timing chain tensioner.
I took the recoil starter cover off & wrenched it over to TDC -
Both my cam's were in fact one tooth off.  I reset them & buttoned everything back up.
  Fired it up & am Finally back to Full Power.  I avoided the timing like the plague but it was in fact the 2nd main problem besides the Intake cam.

         BIG Thanks guy's & Happy New Year!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 
   

[Bratman2]

Glad you got it! Happy New Year to you.