2002 Can-Am Quest 650 - Won't idle

[priglmeier]

I own a 2002 Can-Am Quest 650.

It will start if you massage the throttle a bit and it will continue to run. BUT if you let go of the throttle and try to let it idle it will always die warm or cold.

It has Non-Oxy premium gas, a new gapped NGK plug, a new carb (as of today) and fresh fluids. After installing the new carb it runs exactly the same.

 

I only have a few things that I have observed since the new carb:

1. The choke still doesn't do anything. It has a good cable and it is hooked up. It on fully off.
2. There is a cable in the top, front of the engine that splits into two connectors. The connected side is in the photo. The other side has the yellow banded section and is not connected. I do not see anything in range of this connector so I don't know if this is normal or not???
3. The original carb wasn't really dirty or clogged. I'll use it as a spare.
4. I don't see this cable and connectors listed in the Can-Am shop manual. Looking for some help.

I want to ride!

[priglmeier]

The bottom image is the Oil Pressure switch from what I have found.

The yellow connector in the top image is the one I need to figure out which is on the same wiring harness. thanks

[priglmeier]

Perhaps this is a dead end. The wiring diagram that I found online shows the same wiring to both a metal crimp type connector and the yellow plastic type connector in the top image.

[priglmeier]

I think I need to investigate the carburetor pilot screw or adjust the pin up.down 1 notch?

I need to get it running properly and at the correct idle RPMs. Currently, if you try to shift the CVT is engaged because I always have to keep the idle a bit high and then it moves into gear abruptly.

[priglmeier]

I spent 4+ hours trying to adjust the pilot screw in order to get the machine to start better and run at idle. No improvement. I had it close once and made a very slight adjustment and never got it close again.

So I tried to turn it back to factory settings and follow the shop manual guidelines:

Can_am shop manual states
warm up engine
turn clockwise until engine misses or decreases idle speed
turn counter-clockwise until engine misses or decreases idle speed
center screw between these two settings
unscrew 3/4 of a turn

If idle speed changes after this adjustment, readjust idle speed screw.

 

Nothing.

Edited October 20, 2017 by priglmeier

[Ajmboy]

Does this ATV have a stock exhaust or modified? Sounds like it could be a jetting issue if it's modified. When you give it gas it runs and idles fine, correct?

[priglmeier]

Yeah, it's all stock.
The fuel lines look good. The fuel is non-oxy premium. Fuel is clean. I replaced the fuel filter. No leaks in the fuel lines or carb air connectors that I can see or hear.

[priglmeier]

I have some good news!

I got the carb dialed in and then adjusted the idle. The choke has to be on to keep it idling by itself.

A question about the choke. I have the shop manual and it states that you can adjust the cable tension just below the choke knob area so that it stays in place. I think this is complete BS. There is a small black plastic nut that you can tighten but it seems to make no difference in whether or no the choke pull will stay up (fully choked). The choke always pulls back down to not choked.

Has anyone figured out a good method to adjust this or mod it to work correctly?

Using a small pair of vice grips to hold the choke seems pretty crappy.

[priglmeier]

NOPE. FAIL. GAME OVER!

I decided since it was idling for some time and it was warm that I should try to shift it into gear (nicely) and verify that it would stay running. It stopped running immediately after putting it in gear. So then I tried to reduce the choke a bit and give it a bit more gas after engaging either forward or reverse. It dies each time.

Now I can't get it to start at all.

I checked the plug and it was very foul and black. This may be from when I have been adjusting the carb from lean to rich. So I changed the plug and it will not start. FRACK.

Part of this may be the CVT is still engaging perhaps? I think I have it set quite well... If this is true and the CVT is engaging at a low idle (improperly), do I then need to have the clutch looked at?

[davefrombc]

If  you have to  keep the  choke on to  get it to idle  there  is  a problem with  either with a vacuum  leak,  a  jet  plugged in   the  idle circuit or  possibly  the  floats  are  set too  low  and  not allowing  the  float  bowl  to  fill to the proper level .  Something is stopping it  from  drawing enough fuel,  making it run  lean   at   idle..  Take  the  carb apart .  Blow  our  the   passages  in the  carb.  Blow  them  back,  against  normal  flow ..  "Canned  air"   such  as  that  used  to  blow dust out of computers  works well..  Check the jets , especially  the  main  one  for  tiny holes  plugged. You would  need  a  fine  wire  to  poke  out   any that  won't  clear  with  just  an air  blast. In many  carbs  there  are  tiny  holes  in the  side  near the  bottom of the  main  jet  that  are easily  missed  when  checking    for  blockages.

[priglmeier]

6 minutes ago, davefrombc said:

If  you have to  keep the  choke on to  get it to idle  there  is  a problem with  either with a vacuum  leak,  a  jet  plugged in   the  idle circuit or  possibly  the  floats  are  set too  low  and  not allowing  the  float  bowl  to  fill to the proper level .  Something is stopping it  from  drawing enough fuel,  making it run  lean   at   idle..  Take  the  carb apart .  Blow  our  the   passages  in the  carb.  Blow  them  back,  against  normal  flow ..  "Canned  air"   such  as  that  used  to  blow dust out of computers  works well..  Check the jets , especially  the  main  one  for  tiny holes  plugged. You would  need  a  fine  wire  to  poke  out   any that  won't  clear  with  just  an air  blast. In many  carbs  there  are  tiny  holes  in the  side  near the  bottom of the  main  jet  that  are easily  missed  when  checking    for  blockages.

Perhaps a vacuum issue.

The rest doesn't seem to apply since the carb is new, clean and I have a new fuel filter in place. It was running earlier with choke and idling and now it won't start.

This happened after I attempted run it in gear.

[priglmeier]

I thought perhaps I found something. The hose at the rear of the air box was not seated well. I fixed that.

I did notice the hose on the throttle side of the carb that just dangles there. Is this supposed to connect somewhere? It doesn't appear to connect to the air box for example. See green arrow in picture.

[priglmeier]

IMAGES - New and Original carbs.

[davefrombc]

I'm  not  familiar with the setup  on that  carb  and  motor   but  I'd  guess  maybe  the  dangling  hose  fits  the  carb where  the  black  cap  is?....Just wondering if it  fell  off  the  original  carb  since  you  indicate  it  was open  there  rather than  capped. Where  does  the   connected  end of the  dangling  hose connect? That  might  give  you some  clue ...

I  can  only  make  guesses  from   the  symptoms  described and  those  symptoms  point  to  a vacuum  leak  or  blocked  jet .. Since the  carb  is  new ,  then  I would  guess  a vacuum  problem ,  but  from  where I  can't  say .

Didn't  find  a  free  download  of  a  service  manual  without  joining  an  e  pub site  and  my  anti virus  blocks connecting to  ones  I  found. I'm  leery  of  re-directs  when  searching  for  one  item .      There  are  some  low  cost ones though.   If  you  do  get   a  download  of  one ,  I'm  sure  the  forum  would appreciate you  adding  it  to the  library .

[priglmeier]

Anyone got some detailed pictures of the 2002 quest 650 carb from the top and sides showing all the hose connections?

[priglmeier]

So I literally flipped through my 2002 Quest shop manual and reviewed all the diagrams and pictures.

On pages 04-0205, 04-02-1 & 2 there are some details that show the hose attached from the throttle side and going over the carb and down by the fuel intake line.

There is no connector there between this vacuum hose and the fuel line, so I guess it just hangs in this location. See green line in images. If you have a picture of this and looks different please post it. thanks!

[davefrombc]

It  looks  from  those  drawings the  fuel  pump  is vacuum  operated by  the  hose  connected in the intake right  at  the cylinder  block ..   Could there  be  a vacuum  leak  there  ?  I  have  no  idea  on  the  green  hose  and  have  no  pictures  other  than  what  you  supplied  to  make  any  guesses  from.

[davefrombc]

I  found  a thread on another  forum  describing  much the  same  problem  you  have ..  I'm copying  and  pasting his  problem  and solution :

 

i just got a used 2003 Bombardier Quest 500 with the rotax motor and the po said it needed an oil change because the oil light was on and that was making it cut out. it cranks and idles great, runs good, good trans, steering, tires, etc, but when you give it gas, it cuts out like it has a rev limiter, but it does it in all gears. when i first crank it, it will rev all the way up, but after a minute it starts cutting out. if i cut it off and wait a few minutes, it will rev all the way up again for a minute or so. does anyone know what i can check? ive checked the intake boot, the carb is clean on the inside, ive changed the oil, the oil sending unit is bad, ive grounded out the wire so the light would go off and it still cuts out. what else can i do?
thanks,
chuck

 

 

got it fixed! it was a ground wire pulled out of the MPEM box. now i need a good speedometer and the half round light section beside it, the guy i had fix it flipped it over and messed that stuff up. maybe someone is parting one out.

it was a ground wire coming out of the box bolted to the air box. seems like it was black and grounded to the frame and pulled loose from the plug.

 

I also  saw it  noted  there  is  a  rubber section  connecting  the  carb to  block. . Check there  for  vacuum  leaks too.

That's  the  best  I can  do   to  help. From  other  forums  I  gather  the  problem  can  also  be  from  a  rev  limiter not  reading a sensor right , or  a bad  sensor so  maybe  a  check  of the  wires   to  the  various  sensors  is  also  warranted.

 

 

[priglmeier]

Thanks. I am going to take another look at all the wires. That could explain some of the sudden issues after it appeared to be working (mostly).

I am confident the green hose is just supposed to hang in place now... I found another drawing that shows it does NOT connect to anything at the base of the carb. See picture. I am going to assume the cap on the other side should be in place since it appears to be a black rubber cap like all the others.

I'd really like to end this today with some good news so I can go riding with my 10 year old daughter soon.  

[priglmeier]

Everything is the same now as when I started.

 

I can start the engine this morning, but again the choke does not have any affect and it won't idle and runs rough. This is the exact same symptoms that I started with a week ago.

So if my logic is correct. The original carb was fine. Perhaps it needed some minor adjustment but it was very close to where I am now. I haven't found any loose wires or corroded connectors.

 

I am not sure what to do next?

I really do not want to try re-adjusting the carburetor again. Perhaps this is required, but I'd like an expert to chime in on this if I can find one. I would appreciate it.

 

[priglmeier]

The original carb and the new carb don't have any connections at the bottom. (see picture of original carb) I think this may be the issue... I see some pictures where a new, stock carb has a brass screw in the throttle side of the carb next to the pilot screw. I don;t know if this applies to the can-am carb or not.
The problem is I have never seen these connected, so I don't know the correct setup. I can't find an image or drawing showing any hoses connected to the bottom of the carb.

Anyone got a picture of this from the bottom?

[priglmeier]

Solution: The fuel pump was failing.