View Full Version : poor running B & S 16 hp?

05-13-2007, 05:28 PM
howdy Guys, I am new around these parts and had a question about a mower I put together a while back. its a 16hp twin briggs on a MTD/Craftsman chassie. heres the problem, when I start it and run it its smooth at first and then acts like its not getting gas. I have torn down the carb and cleaned it and have pumped out the tank and refilled with fresh fuel a couple of times searching for what is wrong. I never have found the problem. if you guys have any ideas I could use the help at this point.

Midwest Lawn Services
05-13-2007, 05:50 PM
is this a vaguard?

05-13-2007, 06:11 PM
^^^^ ?

Maybe you should read this; http://www.lawnsite.com/showthread.php?t=144040

Then post some numbers.

BTW, Welcome to LawnSite !

Bill Kapaun
05-13-2007, 06:23 PM
Plugged fuel cap vent?
When it exhibits the symptoms, momentarily loosen the gas cap.
Have you changed the fuel filter?

05-13-2007, 08:33 PM
16hp 656cc model 402707

and yes I have tried it with the fuel cap off. the fuel system flows fuel fine through the line. I am wondering if that style carb needs more fuel pressure from the pump? I am thinking it maybe sucking the float bowl dry. if I pull the choke shut I can keep it running but its difficult to tell where the problem is at.

Bill Kapaun
05-13-2007, 09:16 PM
Inadequate valve lash could cause these symptoms.

05-13-2007, 09:25 PM
so what course of action should I persue to correct bad valve lash? I didn't really plan on tearing it down.

05-13-2007, 09:41 PM
Don't go running to the valves just yet....

When you cleaned the carb. did you take the fuel pump apart ?

If so did you replace the diaphragm ?

Did you get all three springs back in properly ?

If you didn't take the fuel pump apart I feel thats where you need to go, You can get just a fuel pump rebuild kit.
Make sure all three springs are installed per the diagram below, Put a dab of grease on the tabs for the small brass springs to hold them in place for assembly.


05-14-2007, 07:54 AM
Thanks, I'll try that first.