Outdoor Power Equipment and Small Engines - B&S wont start without putting gas in carb

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jl66redcpe
07-03-07, 01:41 PM
It is an old horizontal shaft 2.5 or 3 hp B&S engine. There is no primer bulb. It has a suction type carb where the carb is mounted right on top of the fuel tank. It will not start unless I put a couple drops of gas in the carb. It starts right up and runs fine after that. However if I have to restart it even if warm I have to put some gas in the carb again. I was thinking diaphragm but then why would it run fine after initial start ???? Thanks in advance for all help.

puey61
07-04-07, 05:20 AM
Why, because of inertia and vacuum. The higher the RPM, the greater the vacuum to draw in fuel. Inertia comes into play whereas if you have an intermitent (bad) diaphragm the rotational mass increases the liklihood of maintaining a steady enough vacuum to supply the engine with needed fuel. Replace the diaphragm and you should be good to go.
jl66redcpe
07-04-07, 06:15 AM
Thank you for the explanation. I will replace the diaphragm.