Briggs and Stratton 18 hp twin fuel pump problem


Old 04-15-09, 08:17 PM
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Briggs and Stratton 18 hp twin fuel pump problem

My neighbor recently gave me an MTD yardman riding mower only a couple of years old.The problem was his grandson had ran the 12hp briggs out of oil and seized the connecting rod. I took the mower and with a re-drill of the 4 mounting holes I installed an 18hp briggs twin. The twin runs great, but the problem is it will not start cold.It rolls over and never tries to start even at full choke, but you can remove the breather and pour a trickle of gas in it and it fires up imediatley and runs great. If you restart in a timely manner it will restart, but if you wait a while it has to be primed again to restart.The carb appears to sit higher than the bottom of the gas tank.Is there a check valve in the pump to keep fuel from siphoning out of the pump and back into the tank? I thought of adding a shutoff valve in the fuel line to keep fuel from siphoning back into the gas tank if this is indeed what is happening.I hate to disassemble carb and fuel pump when it runs so well (after you get it started).I woud appreciate anyones thoughts.
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Old 04-16-09, 06:38 AM
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This sounds like a gravity feed system. You will have to find a way to get the gas tank higher than the carb. This may mean buying a shorter gas tank for hood clearance after stufgfing a 2x4 under it to raise the outlet higher than your carb.
Old 04-16-09, 07:09 AM
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Check your choke adjustment, make certain that the choke is closing completely.
You should have fuel in the bowl of the carb for start up.
Old 04-16-09, 10:32 PM
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This engine should have a pump, so you don't have to have the tank up high. The carb bowl should always have enough fuel to start it, as mentioned, and it can't siphon back out. Maybe it's leaking out at the drain plug on the side of the carb? Is the choke closing all the way? I bet it's not closing all the way.

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