346xp carb help

[palbin]

I have simlar problems with a 2010 346xp - it seems to
get too little fuel and too much air - it has to be choked
to start (choke used more than with fresh saw, that is),
and when started one has to keep it alive with trottle as
it stops if trottle is realesed and revs go down too much
- also, it sounds strange when trottle is released - wau-
wau-wau-wau sort of (like a Hemi of trottle perhaps?)
- these problems started off with weak hints of what is
now making the saw more or less unusable - the probl-
ems has then increaed within an hour or so of use to
what it now is - I have removed carburetor and cleaned
its outside and checked that no fule houses are loose -
also I checked through exhaust hole that piston looks
fine (is not "toasted" or so - and saw show no other signs
of having been too warm, and compressions seems as us-
ual) - have also looked into tank and fuel filter which lo-
oks as clean as one could want - I suspect it must be fuel
line or interiror of carburetor - don't want to work more
than necessary - was thinking of

1) try to change carburetor with one of my other healthy
346xp's
2) try to connect sick saw with fuel tank of helathy saw

Is this a good strategy - any other advice?

Thanks and best

Edit: Why are there two fuel hoses to the carburetor by
the way - one on the left side (in?) and one on the right
side (out?) - to my simple understanding fuel only needs
to go into carburetor? (Is it something with returning air
to tank isntead of fuel taken from it?)

 

[old-cat]

If you have a plastic clamp holding the intake to the cylinder, you PROBABLY have an air leak. You need to put a steel clamp on.

 

[blsnelling]

2010 would be a NE 346. I believe they all have the metal clamp.

 

[Big_Wood]

2010 would be a NE 346. I believe they all have the metal clamp.

even the 06+ OE's had metal clamps.

 

[palbin]

"If you have a plastic clamp holding the intake to the
cylinder, you PROBABLY have an air leak. You need
to put a steel clamp on."

OK - thanks a lot - sounds like a possibly easy fix in
that case - (which is just what I was vainly hoping
for ) - will look at that tomorrow - thanks again ... .

PS. I did try to blow the (disconnected from carbur-
etor) fule hoses "orally" so to speak - to see if there
were any big air leeks - but they resited as if tight ... .

 

[sunfish]

First, I'd replace fuel lines & filter. Next try a different carb like you said and report back.

 

[angelo c]

I have simlar problems with a 2010 346xp - it seems to
get too little fuel and too much air - it has to be choked
to start (choke used more than with fresh saw, that is),
and when started one has to keep it alive with trottle as
it stops if trottle is realesed and revs go down too much
- also, it sounds strange when trottle is released - wau-
wau-wau-wau sort of (like a Hemi of trottle perhaps?)
- these problems started off with weak hints of what is
now making the saw more or less unusable - the probl-
ems has then increaed within an hour or so of use to
what it now is - I have removed carburetor and cleaned
its outside and checked that no fule houses are loose -
also I checked through exhaust hole that piston looks
fine (is not "toasted" or so - and saw show no other signs
of having been too warm, and compressions seems as us-
ual) - have also looked into tank and fuel filter which lo-
oks as clean as one could want - I suspect it must be fuel
line or interiror of carburetor - don't want to work more
than necessary - was thinking of

1) try to change carburetor with one of my other healthy
346xp's
2) try to connect sick saw with fuel tank of helathy saw

Is this a good strategy - any other advice?

Thanks and best

Edit: Why are there two fuel hoses to the carburetor by
the way - one on the left side (in?) and one on the right
side (out?) - to my simple understanding fuel only needs
to go into carburetor? (Is it something with returning air
to tank isntead of fuel taken from it?)

I think the second fuel line is for the Purge Bulb.

 

[palbin]

"Purge Bulb" - what is that? - if you mean the primer
that is not the thing - the primer has one hose into it
from the fuel tank (I suppose) and one hose that con -
tinues to the carburetor's left hand side ... .

I have a picture below which is not fantastic because
winter evening dark makes it hard to photo - but one
can see primer stuff on left hand side and in fact two
hoses on righ hand side - on connected to carburetor
and one to its plastic air supply behind ... .

 

[Big_Wood]

you need to get those lines from the purge bulb correct as the bulb is only meant to flow fuel one way. the check valves within the purge bulb could also fail and i've seen it happen many times. your dealing with a new 346 with a zama on it. for a saw to run right the metering side of the carb must be capable of feeding said saw. for that the happen the pump side must be capable of feeding the metering side what it needs to be capable of feeding the saw consistantly. the pump side needs a healthy check diaphragm, fuel pickup, and impulse signal to do it's job. i have a OE 346 with an EL18 on it which was doing exactly what you describe. carb kit fixed it. there is also the need to tune your needles in sync. if you have a lean low speed your throttle plate will need to be closed further to idle it down. so now when you rev it and release the throttle there is fuel left from the high speed feed that can't be burned with the little bit of air the thottle plate is letting by causeing it to die out or drop revs. syncing that adjustment isn't that easy. what alot of people think is synced is a slightly rich low speed compared to their high speed setting. all this will do is puff some smoke when throttling up after a bit of idling and not cause a problem with dieing out when coming off high speed because there is plenty of air already set for the rich low speed.

 

[lone wolf]

Well, Friday, I told my dealer to put my name on the last 346xp he had. Now my old 346 runs perfect Never fails, have had this happen with trucks and other stuff. Maybe just had crap in the carb? Will still do a leak test and check it over good.

Stumpy, I'll probably run by your place tomorrow after I pick up the new saw.

They sell easy enough , no worries.

 

[sunfish]

They sell easy enough , no worries.

Ye they do, but I've never sold one.

Old thread, I ported the old one, then put a new 50cc top-end on it. The new one went to see Randy this past Fall. Plus bought another old one since then...

 

[palbin]

you need to get those lines from the purge bulb correct as the bulb is only meant to flow fuel one way. the check valves within the purge bulb could also fail and i've seen it happen many times. your dealing with a new 346 with a zama on it. for a saw to run right the metering side of the carb must be capable of feeding said saw. for that the happen the pump side must be capable of feeding the metering side what it needs to be capable of feeding the saw consistantly. the pump side needs a healthy check diaphragm, fuel pickup, and impulse signal to do it's job. i have a OE 346 with an EL18 on it which was doing exactly what you describe. carb kit fixed it. there is also the need to tune your needles in sync. if you have a lean low speed your throttle plate will need to be closed further to idle it down. so now when you rev it and release the throttle there is fuel left from the high speed feed that can't be burned with the little bit of air the thottle plate is letting by causeing it to die out or drop revs. syncing that adjustment isn't that easy. what alot of people think is synced is a slightly rich low speed compared to their high speed setting. all this will do is puff some smoke when throttling up after a bit of idling and not cause a problem with dieing out when coming off high speed because there is plenty of air already set for the rich low speed.

Thanks man - I will consider that when I have had time
to digest it - I happen to have a newish (?) looking
Walbro carburetor for a 357xp lying around - would that
fit perhaps?