chainsaw dolmar

[gaz1]

ive got an older dolmar 100 chainsaw

now i think i have a fuel pipe issue its a twin pipe

one side its hard to blow through like its restricted can just hear the air coming out at filter end and the other is clear no restriction blows straight through

ive also pushed a copper wire down the pipe gently to see if it will shift or move the restriction on the pipe with no luck

closest match to the pipe is this



now im not sure on chainsaws more so dual fuel feed line i presume theres no restriction on both fuel feeds on the pipe

can you guys give me help please

 

[frank horton]

not sure on that particular model but all chainsaws and strimmers have a diaphgam in the carb that delivers more fuel than the engine needs....
so there is a return line......these pipe are very small pos 2mm dia......
have u got a clear plastic bubble primer.....this is to prime the carb before starting.....
a lot of the time it or the diaph will perish...... go for the primer buble first... this is the cheapest and easyist to fix.....literally a few squids...
it should deliver fuel from the tank, thru the carb and back to the tank again....u should see the fuel move thru the fuel lines and or the primer bubble...
push the primer slow and steady say 3-4 sec's between pushes.....to fast and sometime it wont pull the fuel...
if the primer bubble is perished or cracked thru lack of use n old age change it and try again...
used to buy the primer bubbles by the 10 pack when I fixed them machines......
this is assuming assuming there is fuel in the tank and the filter isn't blocked....

 

[gaz1]

no its an old make dosnt have a bubble primer

https://store.chainsawr.com/products/dolmar-100-100s-102-chainsaw-walbro-wt-52-chainsaw-carburetor#

i have a fuel pipe going to the back of this as you can see in this pic this is the pipe that is hard to blow through



and one in the middle

 

[8ob]

I might have this model on the workshop cd, some of these carbs take a pulse from the crankcase with a seperate pipe, some pulse a plunger which is like a piston which draws up fuel, some a diaphragm. I will have a look later. Either way its fuel is brought up to the carb using crankcase pulses.

Bob

 

[gaz1]

ive got no idea however i have noticed they can be a vacumm or expansion of air from the gas tank when opening for refilling

from my reference it works on a simple pull syphon system fuel is pumped up the single pipe then splits off into 2 tubes

one to feed main part excelaration side of it ( gives more gas ) ( working ) the other pipe is like a tick over its this part that is not working its hard to blow through the pipe

the other pipe is not is a straight easy blow through

i think ones side of it is blocked but i have no reference on chainsaw pipe parts so dont know if both sides should be easy blow through or one is restricted a little on fuel at that block area ( its really hard to blow air through the tube to the feed filter )

i am familier with the escort/sierra webber twin carb and thats roughly based on same principle i think

 

[mtt.tr]

No these zama and similar carbs are not comparable as they contain a pump which the impulse drives.

This is possibly the best description should give enough knowledge to help you out

 

[pedrobedro]

It's a Walbro wt52 innit ? Can't see why it has two fuel pipes is one a breather ?

not sure on that particular model but all chainsaws and strimmers have a diaphgam in the carb that delivers more fuel than the engine needs....

They have a metering diaphragm pulsed by the impulse from the crank case and a needle valve that delivers as much fuel as it needs.

 

[mtt.tr]

It's a Walbro wt52 innit ? Can't see why it has two fuel pipes is one a breather ?


They have a metering diaphragm pulsed by the impulse from the crank case and a needle valve that delivers as much fuel as it needs.

No the second is for the primer to draw through the chambers just refreshed my memory haven't played with one in about 3 years.

 

[pedrobedro]

No the second is for the primer to draw through the chambers just refreshed my memory haven't played with one in about 3 years.

The saw doesn't have a primer according to gaz. Not many older saws have them.

 

[gaz1]

found a video closely matches what i have

its the one at the top 118.00 thats a restricted/blocked flow hard to blow down the tube seems blocked