F4MLHC carburettor help

[flymikeY]

Motor will not start, but will run briefly when starting fluid sprayed into air cleaner. It will also run briefly if carb top is removed, and gasoline dribbled into idle jet chambers.
So it must be a fuel problem, right?
When float chamber drain plug is removed, a full chamber's worth of gas runs out - so carb is getting fuel delivered.
Engine is not flooding - no smell of gas after 20 pulls on starter.
Carb has been completely disassembled and cleaned. Main jet, air slow jet, and needle valve removed and cleaned. Float and float valve operate correctly.
But still the same symptoms.
Any ideas?

[99yam40]

I would think the main jet and pilot jet need to be clear.
the pilot screw and all of its passages need to be clear also.
does this thing have a choke or maybe a prime start system for cold starts?

[flymikeY]

Thx for the response. Yes, those jets are all cleaned. There is a choke, and it's working normally. I've tried starting fully choked, partially, and no choke.

[99yam40]

well if the fuel bowl is full and all the jets and passages are clear,
maybe the cylinders are not sealing properly to suck the fuel and air in.
or a vacuum leak

or you maybe wrong about the jets and passages

[flymikeY]

I had not thought of lack of compression/suction. I replaced all the gaskets on the inlet side after cleaning the carburettor.
If I remove the carb and put my hand over the air/fuel intake, should I be able to feel suction as I pull the (recoil) starter?

[panasonic]

Was the engine working at all before the carb work was done? Is the engine new to you?

You are sure all the gaskets that where replaced on the intake manifold are correctly assembled and are tight...not sucking air?
And lastly have you done a compression check?

[99yam40]

I worked on an old Craftsman chain saw long ago that the oly way to start it was to shoot a little gas into the carb.
turned out the line from the crankcase to the oil tank(pulse to pressurize the oil tank to oil the chain) had fallen apart.
I plugged that hole in crankcase and it started no problem. had to use the manual oiler to oil the chain

[flymikeY]

Well, I took the expensive route, put a new carb on it - and it started right away, and ran well. So there was something in the old carb that I missed. Out of curiosity, I've since disassembled and cleaned every part of it again, and found nothing - so it's going to die with its secret :-(
I appreciate the (lack of) compression suggestion - I had not thought of that. I did put some plastic wrap over the air intake, pulled the motor through, and saw good suction.

[TownsendsFJR1300]

Well, I took the expensive route, put a new carb on it - and it started right away, and ran well. So there was something in the old carb that I missed. Out of curiosity, I've since disassembled and cleaned every part of it again, and found nothing - so it's going to die with its secret :-(
I appreciate the (lack of) compression suggestion - I had not thought of that. I did put some plastic wrap over the air intake, pulled the motor through, and saw good suction.

Especially the very small carbs, the orifices inside can be very small.

Often, a sonic cleaner will clean out the carb. I've had some small ones, even the sonic cleaner couldn't get em working right..