On Thu, 17 Apr 2008 20:58:56 -0500, "Don Young"
wrote:


"Manjo" wrote in message
...
I have a leaf blower that uses a 5 hp B&S "L" head engine. The carb
is pretty simple with a choke butterfly, throttle butterfly, and
rubber diaphragm fuel pump. The carb sits on top of the fule tank.
The carb has no bowl. The governor linakges are clean and the
governor appears to be working fine.

The leaf blower was starting to run poorly last fall. This spring it
started right up, but after4-5 seconds after running smoothly at
proper speed, it will slowly loose rpms and finally stop after 15-20
seconds.

I have cleaned the pick-up tube, replaced the carburetor diaphragm
fuel pump along with the gaskets between the carb and the fuel tank,
and the gasket between the carb and the engine. I've also
disconnected the engine ground wire that normally kills the engine
when the throttle is tuned full off. But after doing all this the
engine still will not stay running for more than 30 - 40 seconds.

Thanks in advance for any tips, suggestions, or coments.

Manjo
The symptoms sound consistent with fuel starvation. If so, you should be
able to get it to run a bit longer by partially closing the choke or by
squirting a little gasoline into the intake as it starts to die. If that
does not help, you likely have a temperature related ignition failure. That
could be caused by a control module, ignition coil or condenser.

If it is fuel related, first be sure you have good fresh gasoline. Otherwise
there is almost certainly something wrong with the carburetor. Use a
carburetor cleaning spray to be certain that all passages are clean and be
sure you have all the parts correctly installed. If it has one, carefully
check the inlet filter screen at the bottom of the carburetor. A partially
clogged filter could cause it to start after sitting a while but not allow
enough fuel to pass to keep it running.

Don Young


It sounds fuel starved to me. Checking the spark with the plug out and
grounded to the head would tell if there is enough spark (bright blue,
snappy and not a weak yellow). Then I would use a carb /starting
fluid.

As the engine is about to die spray into the carb throat. If the
engine picks up pep, runs higher rpm....check the carb.

*ONE* thing I would be sure to check is the gas line. Look for small
cracks and /or replace.

Next is! How is the fuel filter?