Unable to start Stihl strimmer

[glider26]

Hi,

I'm seeking help here to start my Stihl strimmer (pic below with air filter removed). I took it apart for a good clean having previously purchased it used and running albeit not very well according to the previous owner. I couldn't start it after re-assembly, so I played with the H and L screws on the carb to no avail. I then ordered a new carb (an aftermarket part NOT made by Stihl). I still can't start it. I've tried adjusting the H and L screws on the carb, choking halfway and all the way, and starting it with the throttle fully open. The primer bulb fills up nicely with petrol when primed. When I squirt petrol from a straw directly upstream of the throttle valve, it runs for a couple of seconds, so I know the spark plug isn't at fault. I feel like I'm missing something obvious. Any tips please?

 

[lostinthelight]

Sounds like fuel is not getting drawn into the crankcase caused by low compression or blocked pulse passage to carb (gasket on the right way or is there a pulse tube), air leak at manifold or crank seals leaking, if you keep choke and continue pulling does the plug get wet?
litl

 

[glider26]

ok, I see. I haven't removed the spark plug yet to check for petrol on it but in the meantime, I notice that when I remove the fuel line to the carb after priming for a while, there is quite a bit of pressure built up in there and upon removal petrol squirts all over the place. Is that normal? And I certainly can see any signs of wet on the throttle valve.

 

[glider26]

Also worth noting is that one of the two bolts that binds the green part between the carb and the engine block seems to turn loose. see pic below (before cleaning!). The part stills seems tight against the block, but could that be the source of a leak that causes poor compression and hence no draw of the air/fuel mix? Again, with fuel dropped directly into the carb, the engine runs for a few seconds.

 

[lostinthelight]

Also worth noting is that one of the two bolts that binds the green part between the carb and the engine block seems to turn loose. see pic below (before cleaning!). The part stills seems tight against the block, but could that be the source of a leak that causes poor compression and hence no draw of the air/fuel mix? Again, with fuel dropped directly into the carb, the engine runs for a few seconds.

A leak there would not cause poor compression, thats the other side of the manifold in the cylinder but could reduce or stop fuel/air being drawn through the carb ....sounds like the thread is damaged from cross threading or over tightening so needs further investigation
litl
Edit: carb doesnt look like its square or is it camera angle?

 

[Burnerman]

Can you see the pipe that's connected to the bottom of the green heat insulator block.....is it connected to anything?
Set the H and L screws back to one turn out from fully in.
John