QuestionQUESTION: Hi John
I have a GARDENLINE PETROL CHAINSAW GPCS-42cc fitted with a WALBRO WT746 527 CARB Purchased from ALDI cheepo £90 three years old.
This saw was working for about one hour cutting down a tree before it just stopped, i thought it had run out of fuel
so put some in. Still did not work symptoms are carb or electrics or compression so
1 CHANGE THE PLUG NO JOY
2 PUT A FEW DROPS OF PETROL INTO THE PLUG HOLE PUT THE PLUG BACK IN AND IT FIRED UP FOR A FEW SECONDS THEN STOPPED. This proved the ignition and comp was OK even if there was lot of smoke
2 STRIPPED DOWN THE CARB CHECKED THE DIAPHRAGMS (they seem OK) BLEW OUT THE JETS WITH A CAR ELEC AIR PUMP CLEANED EVERY THING PUT IT ALL BACK STILL NO JOY NOT EVEN A COUGH
I AM AT THE LIMIT OF MY KNOWLEDGE
CAN YOU HELP
ANSWER: Sorry for the delay in responding, I have been searching for at least a little info on the saw you are talking about, they must
not be here in the states.
In general, from what you described, is indeed a fuel related problem
but with the engines we are discussing, can involve more than just the carb and fuel line.
The fuel /air mix is pulled through the carb, into the crankcase, then introduced to the cumbustion chamber, and so any air leak in the saw, can adversely affect the saw's running, so observing
anything that has vibrated loose, can indeed be the problem.
But first, remove the muffler and take a look at the piston,
and if you see scoring damage, then the saw is pretty much done in
as replacing the piston, etc., would be cost prohibative.
A saw with a damaged piston could still run a little when primed.
Check this, and inspect the fuel line for cracks, tell me whether or not the saw has a primer/purge bulb, etc. and we will see if this
saw is fixable or not.
---------- FOLLOW-UP ----------
QUESTION: Hi John
Thanks for your info.
I find the Internet truly amazing that i am talking to a guy i the states about my problem!! (i don't know what is up with this little old country)
When i was working abroad communication was measured in weeks by TELEX, well enough with all our yesterdays.
1 THE PISTON ON INSPECTION THROUGH THE INTAKE SEEMS OK
2 HAVE CHECKED THE FUEL LINES HAVING TAKEN OFF THE CARB
AND PRIMING THE BULB THERE ARE NO VISIBLE LEAKS AND NO
PETROL(GAS)ABOUT. BUT WHEN THE BULB IS PRESSED TO DRAW
FUEL ON THE RELEASE OF THE BULB, FUEL COMES FROM THE TANK
THROUGH THE CARB BUT THE OUTLE PIPE TO THE BULB SEEM TO
HAVE AIR BUBBLES IN IT!! NOT KNOWING MUCH ABOUT MONOBLOCK
CARBS IS THIS NORMAL (GIVE ME A COUPLE OF 40DCOEs ANY DAY)
THE OTHER THING IS IF THE BULB IS PRESSED AND RELEASED
A NUMBER OF TIME IN SUCCESSION SHOULD FUEL BE INJECTED
THROUGH THE FLOAT CHAMBER DIAPHRAGM INTO THE AIR INTAKE.
IF THIS IS SO THEN THAT IS NOT HAPPENING
Regard
Athol
ANSWER: It is not a true "primer", actually a purge bulb. Fuel is to be pulled through the carb, so the fuel should be heading back to the
tank.
The line with the fuel filter should come to the nipple closest to
the cover with 1 screw holding it on, that is the fuel pump side.
The other line should be closest to the side with the cover with the 4
screws, that is the metering side. And that is where the fuel is pulled from the carb, then through the bulb, and back to the tank.
Recheck the line routing, and get back to me. Does the carb have adjustment screws as well? Let me know.
Fish
---------- FOLLOW-UP ----------
fuel lines
QUESTION: Hi
The fuel line lay out are as you have described.
The high and low end screws have no adjustment.
Have sent images hope you get them!!
Athol
AnswerActually, your two adjustment "screws" are inside that 8 shaped
hole on the right in the pic.
They are of course tamper resistant, so adjustment is difficult.
I have used a number of things to get on them to grip and turn them,
the most success I have had, is using a little insulated electrical
"butt" connecter, which here the red ones seem to be the correct size to shove onto these acrews, and turn left to richen the mix.
If the carb was just a little bit clogged, you should be able to keep it running with a shot of fuel and keeping the choke engaged.
The screw farthest from the engine is the high speed mixture, the
closer one is the low.
