Question-------------------------
Followup To
Question -Hi Eric just to let you know, i dropped the carb in to a bucket of water & pumped a small amount of air in to it & found the carb body was porus & leaking air, so i mixed up some glue & smeared it over the affected area & it worked, saw runs fine
thanks anyway for your help, your effort was appreciated.
reguards Bryan
-------------------------
Followup To
Question -if pulse is working fine, should the drop of oil be sucked in & blown out of pulse hole when piston moves up & down? yep needle valve looks fine, not worn at the tip, arm is streight & level with body, both gaskets & daiphragm look o.k. on both sides of carb, insulator block looked a little warped or twisted but this came right after running across some sandpaper.
-------------------------
Followup To
Question -Eric the saw wasn't running due to no fuel getting through to the carb, but squirting fuel in to carb & it would fire & run until the squirted fuel has been used up, i've run a seperate clear external pipe out of top of fuel tank to carb fuel inlet pipe & started saw by squirting fuel in to carb but still no fuel is sucked up clear pipe to carb.
When i check crankcase pulse hole by dripping a drop of oil in to hole & pull starter cord should the oil be sucked in to the hole or blown out of the hole? is there supposed to be a 1 way valve there to make the diaphram work only 1 way?
Hi Eric, i'm working on a zenoah 380av chainsaw,
after fitting a new carb kit, i cannot get fuel through the fuel pipe up to the carb, i've checked the insulator block & gasket,the pulse hole vent into the crankcase is clear, i can see the piston move up & down, I assume that this could make the diaphram in the carb move in a motion to suck and blow fuel up and down the fuel pipe, should there be a one way valve either in the pulse hole (crankcase) or a valve in the Walbro carb I think it's a wa113a, i am perplexed & going bald from tearing my hear out, any help would be much appreciated thanks
reguards Bryan
Answer -
Let me know for sure the carb number.
There should be 2 halves to the carb. One side it the fuel pump and the other is the metering side. The diaphragm side with the inlet needle is metering side which lets the fuel into the engine based on the crankcase pulsing.
The other half is the fuel pump side. This side should have a diaphragm and gasket. The diaphragm has to be next to the main carb housing for most Wal-bro carbs. Make sure you have the right diaphragm and the holes and two flapper valves match the carb body.
On the metering side you need to pay attention to the inlet needle arm height. This is like setting the float level on an older automotive carb. Most Wal-bros have the needle arm sitting flush with the carb housing or carb floor if it has a pocket.
Was this saw running before you rebuilt the carb?
Let me know.
Eric
Answer -
The pulse sounds like it's working fine. The porblem has to be in the carb.
Did you check the placement of the fuel pump diaphragm and gasket? Normally the diaphragm is next to the main carb body and then the gasket.
On the metering side the gasket usually goes on first and then the diaphragm.
Did you check the inlet needle height?
Let me know.
Eric
Answer -
The pulse will suck and blow...this operates the fuel pump side of the carb.
Make sure the hole in the insulator and engine block match up; same for the carb and insulator. It's easy to put some gaskets on incorrectly and blocking the pulse hole.
Eric
AnswerVery, very interesting. I can't recall any chainsaw carbs being porus or ever warping. We've seen this on several older Briggs engines where the carb leaked but the insulator on most saws and trimmers usually prevents this.
Thanks for the update.
Eric
