TS400 won't start after engine rebuild

[Dan Maynard]

13 hours ago, Shaffick said:

Hi there. Why would it score up after a rebuild?. 

I don't know the machine, but a general risk from rebuilding is a slight error eg intake boot not assembled as airtight, then everything is new but as soon as it starts and you get it off choke it's running lean with insufficient lubricant.

[spudulike]

Did you de-stress the crank bearings after screwing the crankcases together? Unlikely to stop the engine running completely but usually missed by many.

The rest of it, could be anything and depends on your experience in rebuilding engines and fuel systems.

[Shaffick]

1 hour ago, spudulike said:

Did you de-stress the crank bearings after screwing the crankcases together? Unlikely to stop the engine running completely but usually missed by many.

The rest of it, could be anything and depends on your experience in rebuilding engines and fuel systems.

Yes definitely de-stressed the bearings as the workshop manual states. Thanks.

[Shaffick]

I done a few checks in regards to what people have posted and it's not a sheared flywheel key as posted previously. I ordered a new ignition coil and aftermarket carburettor. This was simply for trial and error. I previously didn't mention that there was fuel leaking from the air filter housing (the air filters have been removed). I fitted the new coil and new carburettor. I changed the fuel pipe which leads to the the fuel filter in the tank as well as the fuel filter. Filled up with fresh fuel and it started for about a few seconds. There was still fuel coming out of the air filter. I looked at a few yo*t@be videos and seen a few comments about the metering valve and needle valve. Most of the comments mentioned that the new valves may not be as good as the original valves (bit baffled by this) so I decided to have a look at the original carburettor and I changed the new valves with the original ones. I couldn't see any difference. I refitted the old carburettor and now the saw starts but only with throttle applied. Still leaks fuel from the air filter. Could anyone advise on what to do next please?.

[adw]

Stating the obvious the inlet needle is leaking, so either the metering lever is too high, or the metering diaphragm is too stiff, the rubber tipped needle is worn, orn the seat itself is worn, which is pretty normal on an old power cutter due the abrasive dust passing through the carb, when you changed the carb, was it a Chinese copy carb? at best they are not very good.

[Shaffick]

9 hours ago, adw said:

Stating the obvious the inlet needle is leaking, so either the metering lever is too high, or the metering diaphragm is too stiff, the rubber tipped needle is worn, orn the seat itself is worn, which is pretty normal on an old power cutter due the abrasive dust passing through the carb, when you changed the carb, was it a Chinese copy carb? at best they are not very good.

Yes, the carburettor is a cheap copy. But surely the cheap copy shouldn't be leaking fuel aswell?

[adw]

Quite possibly, does this machine have a purge bulb? If so have you connected the pipes up in the correct orientation? remember it’s a purge so pulls fuel from the carb and dumps back to tank, not pumping fuel into the carb.

[Shaffick]

1 hour ago, adw said:

Quite possibly, does this machine have a purge bulb? If so have you connected the pipes up in the correct orientation? remember it’s a purge so pulls fuel from the carb and dumps back to tank, not pumping fuel into the carb.

Hi again. No, there's no priming bulb. I'm starting to think it might be the breather pipe. Got my head baffled. I've checked the metering and needle valve on both carburettors and they both seem fine and free from any wear. The adjustment seems fine also. I've eliminated any problem with the compression and ignition. This is definitely a fuel/air problem.

[Shaffick]

I managed to get the saw started on idle, but when revs were applied and released it cut out and the fuel was leaking out of the air filter housing.