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Stihl BR340

#1

U

Uncle Dave

Need advice. I have a still br340 blower, runs great for 30-45 mins then Boggs down. Cuts off. I start again it runs 10 mins. After 4th 5th time won't crank. I've changed gas, plug, air filter, tank filter,exhaust screen cleaned/torched it. Any suggestions appreciated.


#2

tom3

tom3

Does the engine tighten up, can't pull the rope? Or just won't run? I have a couple 2 stroke machines that will lean out after several minutes and need the high speed mixture adjusted some, worse on a hot day. Just a quirk of the cheap carbs I suspect.


#3

B

bertsmobile1

The fuel tank & carb run at 7 psi
This pressure is regulated by either the cap or a tank vent or both.
If it not regulated then the tank overpressurizes and the engine floods after a short while.
A 2 stroke will make very different noises when stalling rich as comparred to stalling lean.
If the vent /cap is blocked it will flood & stall rich ( Bog down, 4 stroke, miss a bit then stop )
If they are leaking then it will run lean which will cause the exhaust note to become quite sharp & harsh then the engine will race away then die.

The final entry on the usual suspects list is a partially blocked screen in the muffler which prevents all of the exhaust getting out till the engine eventually chokes on it's own exhaust, however this usually happens after 3 to 4 minutes but always worth a check


#4

I

ILENGINE

When the engine gets to where it doesn't restart make sure you still have spark at the spark plug. These symptoms can also mimic the results of a failed ignition module.


#5

U

Uncle Dave

tom3 said:
Does the engine tighten up, can't pull the rope? Or just won't run? I have a couple 2 stroke machines that will lean out after several minutes and need the high speed mixture adjusted some, worse on a hot day. Just a quirk of the cheap carbs I suspect.
Click to expand...
ThanksTom


#6

U

Uncle Dave

ILENGINE said:
When the engine gets to where it doesn't restart make sure you still have spark at the spark plug. These symptoms can also mimic the results of a failed ignition module.
Click to expand...
Thanks


#7

U

Uncle Dave

bertsmobile1 said:
The fuel tank & carb run at 7 psi
This pressure is regulated by either the cap or a tank vent or both.
If it not regulated then the tank overpressurizes and the engine floods after a short while.
A 2 stroke will make very different noises when stalling rich as comparred to stalling lean.
If the vent /cap is blocked it will flood & stall rich ( Bog down, 4 stroke, miss a bit then stop )
If they are leaking then it will run lean which will cause the exhaust note to become quite sharp & harsh then the engine will race away then die.

The final entry on the usual suspects list is a partially blocked screen in the muffler which prevents all of the exhaust getting out till the engine eventually chokes on it's own exhaust, however this usually happens after 3 to 4 minutes but always worth a check
Click to expand...
Thanks


#8

Fish

Fish

Take off the muffler and peek at the piston.


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