Strange symtoms on 17hp

[Zav_5669]

I have a vertical shaft 17hp ohv briggs that will only run at idle for maybe a minute then backfires and dies. Compression is good, flywheel key is good, compression is good, valve lash is good, and spark is great. As far as i can tell timing is good. Tia.

 

[Bertrrr]

Carb

 

[slomo]

Almost another has all required but won't run post.

 

[Fish]

Take off the rocker cover again, and watch the rocker arms moving while rotating the engine by hand, see if they both open/close the same, that the valves are opening about the same distance, etc..

 

[Zav_5669]

Thanks for the replies. It has a carb off a running mower. The valves are opening and closing as they should and the decompression is working.

 

[slomo]

Flush out the fuel tank and install new lines from tank to carb.

 

[Fish]

Thanks for the replies. It has a carb off a running mower. The valves are opening and closing as they should and the decompression is working.

So you watched the rocker arm travel?

 

[bertsmobile1]

OK Zav we will do it this way.
Get a can of carb cleaner and start the engine
As soon as it starts give the carb short shots of carb cleaner ( air filter removed ) and keep on doing this for for a minute or more ( it will run rough & sound aweful ).
If you can do this then you have a fuel problem
If you can not do this then you have an electrical problem
Let us know what the results are .

 

[Zav_5669]

OK Zav we will do it this way.
Get a can of carb cleaner and start the engine
As soon as it starts give the carb short shots of carb cleaner ( air filter removed ) and keep on doing this for for a minute or more ( it will run rough & sound aweful ).
If you can do this then you have a fuel problem
If you can not do this then you have an electrical problem
Let us know what the results are .

If i ket it sit for a couple days it will run perfect for a few minutes then it acts like i turned the key off. No sputtering. Im stumped

 

[bertsmobile1]

If i ket it sit for a couple days it will run perfect for a few minutes then it acts like i turned the key off. No sputtering. Im stumped

That is not what you were asked to do
If you do not do what your are asked to do then post the results I can not help you because the mower is there in front of you, not in my workshop .