346xp problems

[palbin]

Hello!

My oldest 346xp (a 2010 - I have two 2011 as well) has a problem
- it seems clear it gets too much air - which makes it necessary to
choke it excessively in order to make it start - after that one must
more or less have it throttled all the time to make it "stay alive" -
and in doing so it revs more that it should and revs down very slow
and unevenly etc - TOO MUCH AIR must be the problem I have
concluded ... .

I have tried all easy fixes - including trying other carb, other spark
plug, other decomp valve, checking tank vent, chaning fuel filter etc
and so on ... didn't work - now I have dismanteled the thing into pe-
aces - I have the crankcase part with piston comin up from it still as
a (non-dismanteled) unit - but everything else is screwed loose ... .

There seems to be no obvious faults, unfortunately ... .

1) I can see that the fuel hose is a little weakened at the point were
it passes into the fuel tank - guess vibrations can cause that - I have
pressure tested it just a litlle with bicycle pump - seems clear
from that if there is a leak it is very very minute - as I couldn'rt see
any airbubbles in water tank with fuel hose submerged being some-
what pressurized by bicycle pump - could a very very minute leak
here still be the culprit?

2) The impulse hose (whatever is the functioning of that) seems very
intact except possibly that the fittings of it could be ever so slightly
"tired" (from vibrations I guess) ... could that be a problem?

3) I have quatilty fuel hosing in great supply with a slightly bigger
outer diameter than the original, so I was thinking of replacing all
hoses with new quality ones and drill just a little in the plastic to ma-
ke the the new ones fit ... ?

Something I have read about in workshop manual that I do not un-
derstand what it is - DIFFUSER JETS - WHAT IS THAT ? (It is
listed as a possible culprit in trouble shooting list - except for this one
and the items above I have tested everything ... .)

THANKS

 

[sunfish]

Should have replaced the fuel line before taking it all apart. Could have been a simple fix, or not?

 

[palbin]

Yeah - well I am no pro mecanic - just an accidental one -
still I have to take loose the tank for replacing fuel hose - and
that is not so much less trouble than dismantling the whole
thing ... .

When I could see no obvious faults with fuel supply I decided
it was best to check impulse hose (whatever that is for?) as well
as inlet manifold when I was at it as this was what many folks
suggested typically was the problem ... .

 

[Big_Wood]

more then likely not enough fuel rather then to much air.

 

[Gypo Logger]

Not that this will help but I was working on a 257 that needed excessive choking so I pulled the pump side of the carb off and the screen was plugged with fine sawdust to the top of the housing.
So I checked the tank out and the filter had come off. It must have run a few tanks like that.

 

[sunfish]

Yeah - well I am no pro mecanic - just an accidental one -
still I have to take loose the tank for replacing fuel hose - and
that is not so much less trouble than dismantling the whole
thing ... .

When I could see no obvious faults with fuel supply I decided
it was best to check impulse hose (whatever that is for?) as well
as inlet manifold when I was at it as this was what many folks
suggested typically was the problem ... .

Your saw is too new to have problems with the impulse line or intake manifold, but is about due for a new fuel line. It might also be tank vent and or fuel filter, or just trash in the carb. Doesn't sound at all like an air leak.

 

[Roll Tide]

I'd also check your intake boot and see if hasany cracks, or if its loose on the engine block.

 

[Big_Wood]

it seems he tried everything. the **** Zama carb on this saws has a pump side diaphragm that krinkles right up when left to sit especially with ethanol. it then struggles to supply fuel to the metering side and can be partly corrected by richening up the needles. carb kit and fuel filter if it were my saw. i bet the orignal fuel line is just fine. the problem is most likely a varnished all the hell fuel filter in combination with tired carb diaphragms if it did any length of sitting before this.

 

[palbin]

OK - I was also thinking of taking away primer side of fuel
line by putting in totally new El42 carb (with no primer in-
let) just plugging the corresponding whole in tank - the saw
has modified muffer (from "High Rew Saw Works" ) so -
possibly could use a little bigger carb - but I will replace main
fuel line then - drilling little in corresponding whole in tank -
I think original fuel hoses are 5 mm while my backup one is
6 mm (with thicker material but same inner diameter ...).

 

[Big_Wood]

i would find a line with original quality or don't replace it. put a piece of tygon in a bowl of non ethanol fuel for a few months and then tell me what you think. don't know what would happen in ethanol fuel.

 

[sunfish]

My old 2001 346 has needed a new fuel line every 3-4 years. Also a couple used ones I got had bad fuel lines. My 2011 346 still has the original line, but expect it to start leaking any day now...

 

[Big_Wood]

it could also be the primer bulb that's shot. it has little check valves in it that only open and close when the bulb is pumped. if the check valves are stuck open the pressure drop in the venturi will pull fuel but fail to pull metering side diaphragm enough the open fuel needle starving engine of fuel. alot the take in. start with the basics and just do a carb kit and fuel filter. i bet it runs just fine. count how many turns the needles are at if you don't know how to tune a saw.

 

[palbin]

"intake boot" - I am not totally familiar with this glossary
- if it is the inlet manifold I have dismanteled it - it seemed
to sit very snug around cylinder intake ... .

I have switched fuel filter to new one --- no change ... .

I have also switched carb - the original EL32 to this ome
- whatever it is



I also have a spare Wallbro carb (besides a spare EL42) -
both for 357xp (without primer) - but I have switched carb
once already ... .

 

[sunfish]

OK - I was also thinking of taking away primer side of fuel
line by putting in totally new El42 carb (with no primer in-
let) just plugging the corresponding whole in tank - the saw
has modified muffer (from "High Rew Saw Works" ) so -
possibly could use a little bigger carb - but I will replace main
fuel line then - drilling little in corresponding whole in tank -
I think original fuel hoses are 5 mm while my backup one is
6 mm (with thicker material but same inner diameter ...).

Use OEM lines and do not enlarge the holes in the tank...

 

[Big_Wood]

My old 2001 346 has needed a new fuel line every 3-4 years. Also a couple used ones I got had bad fuel lines. My 2011 346 still has the original line, but expect it to start leaking any day now...

my 372 is a 2000 and it's still running the original line. i check it every so often and it's pretty well just as good as new. it gets used all the time though. never sits with old nasty gas. same line as what's in your 346. you must be running ethanol enriched fuel LOL.

 

[sunfish]

i would find a line with original quality or don't replace it. put a piece of tygon in a bowl of non ethanol fuel for a few months and then tell me what you think. don't know what would happen in ethanol fuel.

Since he is in Sweden, he likely has no ethanol in the gas there. Maybe?

 

[sunfish]

my 372 is a 2000 and it's still running the original line. i check it every so often and it's pretty well just as good as new. it gets used all the time though. never sits with old nasty gas. same line as what's in your 346. you must be running ethanol enriched fuel LOL.

No ethanol in the last 4 years, but some before.

 

[palbin]

It is NOT with carb screws (T-L-H) - I have more
knowledge than too be fooled by that ... .

 

[Big_Wood]

i would find a line with original quality or don't replace it. put a piece of tygon in a bowl of non ethanol fuel for a few months and then tell me what you think. don't know what would happen in ethanol fuel.

Since he is in Sweden, he likely has no ethanol in the gas there. Maybe?

i don't run E fuel either. tygon goes all gooey in even non E fuel when submerged.

 

[sunfish]

i don't run E fuel either. tygon goes all gooey in even non E fuel when submerged.

I never run Tygon line.