Sport Today

I have a 1979 John Deere Spitifre 340.  My problem is that the sled will
not idle when warmed up.  The carburetor has just been rebuilt
(disassembled, cleaned and returned to stock settings).  I seems to be
lacking fuel pressure at idle warm and has a slight bog on
acceleration.  How do the fuel pumps operate?? how are they tested, and
can they be repaired??  Thanks to all in advance.

Hello,
Pumps can be repaired and they opperate off of crankcase pressure.If the pump
was the problem,  it would show up more at high speed.  I believe U may have a
deeper problem with possibly compression or a crankcase air leak.  U may need
to see a snomobile dealer to have these items checked.  Betting on a air leak.

Who did the cleaning job?Many times someone unfamiliar with snowmobile or
bike carbs will overlook things.  I'm betting the pilot jet is still dirty,
or the passageway it feeds is obstructed- your symptoms point to this.. have
it opened up again, spray out all the passages with contact cleaner or brake
cleaner, observe the flow of cleaner through the various holes,hold the
pilot jet to a light to make sure it is open.The pilot jet is cheap, replace
if you can't clean it out.  Jerry France

your  fuel pump may be the problem  i don't know how to fix that but it sounds
like you have a hole in the gasline