Hello, new here. I have a Snapper mower with Briggs 12G702 and carb 498964. I cannot get the carb to stop leaking fuel out of the throat. I know that most of the time it is the needle seat that is the culprit but I have tried 3 new B&S original carb kits and replaced the float, needle and seat to no avail. It looks like it is seeping out of the emulsion tube because the throat is wet but the vents look dry. Just wondering if I am missing something here. I have several Briggs powered pieces of equipment and have never had an issue with rebuilding the carb and having it leak like this..
If fuel is coming out the emulsion tube then the fuel is either too high or under pressure or both .
Try loosening the fuel cap .
If a needle & seat is working the carb should hold back 10 psi pressure on the fuel intake line .
Are you sure you installed the float seat correctly? With Briggs part number 398188, needle and seat, the seat has a ridge on one side which must be installed against the carb body, not toward the needle. If the needle and seat are working correctly, the next cause would be that the bowl gasket is not sealing the bowl to the carb body.
Thank You for your replies. The seat was installed with the ridge side up into the carb. I can see no reason for the tank to be under pressure, it doesn't hiss when I loosen the cap. I will recheck the seat again. Thank you for your help.
Something obscure but could be an issue. Is there anything blocking the bowl vent between the air filter housing and the carb . Gasket blocking vent, or RTV sealant used between the air filter housing and the carb.
#6
StarTech
How the area where the seat fits into looks? it rare but damage could be there allowing the fuel to seep around the seat. Just a thought as I had a couple over the years to damaged.
Remove the float bowl& tip the carb upside down.
If the seat & float are installed correctly then the float will be horizontal when the carb is vertical.
And when you blow through the fuel intake spiggot it will be closed with nothing more than the weight of the float
If the float sits up at the free end then the needle is too long or the seat is not fully home.
I generally us a touch of silicon spray as a lubricant to get the seats down all the way .
If the float is lower at the free end then the needle is too short or the float is damaged .
