Hello, I did a search and didn't come up with much.
I have a ~20 year old Briggs 98902 mower that was given to me. The governor spring set had been broken off somehow and I connected the governor vane to the throttle plate with a paperclip. The mower ran great at about ~1500 RPM and I proceeded to fill it up with fresh e10 gas and go mowing. About 45 minutes into the mow, the RPMs suddenly dropped to about 400 RPM and would stall under any load. With no load, it would idle at this speed indefinitely.
I hosed down the carb with carb spray (it's a pulsa-prime with the plastic carb over the tank) and pressed the primer bulb a few times. It cranked right up and ran great for about 30 seconds, then went back to the 400 RPM lope.
Pushing the primer bulb while running causes it to stall.
Spraying carb cleaner in it while running causes it to stall.
Opening the throttle plate in this state (remember the springs are gone) causes the RPMs to pick up for maybe 3 seconds and then it stalls out.
Tilting the mower back causes the speed to pick up a bit, I'd guess maybe 800 RPM, but returning to level makes it go down to 400 again.
I put the mower away for a week and when I came back the primer bulb wouldn't do anything. I took the diaphragm out and hosed it down, and got the primer to work. (It looks like there's a check-flap that vents pressure before the bulb sucks fuel in.) Put it back together and it cranked right up. Ran great (~1500RPM) for 30 seconds, then 400 again.
I'm guessing there's a carb issue but I don't want to dump too much money into this mower, as it's in pretty rough shape. Any ideas?
Thanks
I have a ~20 year old Briggs 98902 mower that was given to me. The governor spring set had been broken off somehow and I connected the governor vane to the throttle plate with a paperclip. The mower ran great at about ~1500 RPM and I proceeded to fill it up with fresh e10 gas and go mowing. About 45 minutes into the mow, the RPMs suddenly dropped to about 400 RPM and would stall under any load. With no load, it would idle at this speed indefinitely.
I hosed down the carb with carb spray (it's a pulsa-prime with the plastic carb over the tank) and pressed the primer bulb a few times. It cranked right up and ran great for about 30 seconds, then went back to the 400 RPM lope.
Pushing the primer bulb while running causes it to stall.
Spraying carb cleaner in it while running causes it to stall.
Opening the throttle plate in this state (remember the springs are gone) causes the RPMs to pick up for maybe 3 seconds and then it stalls out.
Tilting the mower back causes the speed to pick up a bit, I'd guess maybe 800 RPM, but returning to level makes it go down to 400 again.
I put the mower away for a week and when I came back the primer bulb wouldn't do anything. I took the diaphragm out and hosed it down, and got the primer to work. (It looks like there's a check-flap that vents pressure before the bulb sucks fuel in.) Put it back together and it cranked right up. Ran great (~1500RPM) for 30 seconds, then 400 again.
I'm guessing there's a carb issue but I don't want to dump too much money into this mower, as it's in pretty rough shape. Any ideas?
Thanks