Need help w/ my damn mower.
 

It's a Murray w/ a Briggs and Stratton motor.. Damn thing only stays running w/ the choke on.. take choke off.. it dies. I've put all new fuel filters on it.. wondering about bad gas.. but not sure. any ideas? I've checked all fuel lines.. ran through the whole thing.. blew out carb, all of that

Re: Need help w/ my damn mower.
 

Damn I was gonna say carb.

Re: Need help w/ my damn mower.
 

You need to clean the fuel pump on the carb. How many bolts are on the fuel pump? If it's a 3 bolt fuel pump they don't flow as much. The 4 bolt ones suck much more fuel. The problem that you're experiencing is not enough fuel, I can guarantee it. So you can do a few things... clean the fuel pump, find a new 3 bolt which is easy because every old briggs twin has one, or find a 4 bolt fuel pump which is on the newer briggs non-ohv. Your's is an opposed flathead, right? It's not bad gas and it's not fuel the fuel filter, it's that the pump isn't sucking enough gas. Another thing you can do is pull the whole pump off the front of the carb and run a gravity feed of gas, but that would require fabricating a bracket to hold a fuel tank above the engine.

Re: Need help w/ my damn mower.
 

have you tried here http://forum.doityourself.com/showthread.php?t=265753

Re: Need help w/ my damn mower.
 

Oh yeah another thing you can do is pressurize the fuel tank with 2psi, that will push the gas through the lines. The fuel pumps on the carbs of briggs opposed twins are operated by vacuum pulses and they only pull 2-3psi, but the diaphragms in them are weak as ----. Spray carb cleaner directly into the jets as well with the little red hose thingy.

Re: Need help w/ my damn mower.
 

Yeah it's a 3 bolt fuel pump. I've spent probably 2 hours of trying different things w/ that pump as far as cleaning it, got a new spring/gasket rebuild kit for it, but nothing seems to make the mower want to stay running without the choke on. I've tried other forums. ---- just doesn't seem right.. I know it's probably something simple that i'm missing.. but i've cleaned the hell out of the carb, filters, pump. Forums were saying that the jet needed cleaned but I sprayed that bitch out too. I'm getting great spark, plugs are a good, new coil. whats the best way to pressurize a fuel tank?

Re: Need help w/ my damn mower.
 

Well there's really no best way since the caps, at least on mine, had valves in them. I would try finding a different carb. My race mower was like that. If I had no choke it would sit but if I gave it full throttle it would sputter and have a super low rev limit. However, if I got it going then gradually opened the choke from closed to open as I was accelerating it would work fine. Your best option at this point is to find a new carb, they shouldn't be more than a few bucks on ebay. You could even try a bike carb and make a custom manifold. On my next race mower I'll be doing this along with running a solid rear axle.

Re: Need help w/ my damn mower.
 

lol @ race mower!

Re: Need help w/ my damn mower.
 

Sorry my lawnmower goes faster than your car >:D

Re: Need help w/ my damn mower.
 

is your jet clogged up? float arm bent? needle not coming unseated?

Re: Need help w/ my damn mower.
 

how much boost are you running? :P

Re: Need help w/ my damn mower.
 

Have you tried changing your air filter? I had a briggs do that on me more than once. But cleaning the air filter always fixed it

Re: Need help w/ my damn mower.
 

went 45-50ish on gravel roads with my old out of tech race mower

Re: Need help w/ my damn mower.
 

Word, I just got a new one I'm making into a racer. The biggest problems last season were I used an open diff rear end (which sucks ass in mud) and I didn't set up my steering to self-right so I would always have to turn it back to go straight. Other than that it would tear it up even with just a stock 20hp briggs opposed.

Re: Need help w/ my damn mower.
 

12hp block making 17ish hp natural, now running double digit boost via smog pump. boost y0!