Hi, I'm usually pretty able to fix and maintain my lawn mowers, but I bought a 38 inch bolens 15.5hp brigs mower that the person said would start but not stay running. I thought that as normal they just had a clogged air filter or something simple...
Thus far I've replaced the Air filter, Cleaned the carb, Changed the fuel solenoid, new spark plug, new spark plug ignition coil, new oil change, new battery, new gas... and I've pretty much ran out of things to replace....
The mower starts, then after a random amount of time will begin to choke, and slowly die, it acts like it's just not getting fuel however if I wait four to five seconds it'll restart while choked and then die shortly after. It sometimes lasts ten minutes other times thirty seconds. I've tried everything I could think of, the only thing that is a remote possibility that I can think up is maybe the exhaust is plugged? I ran it without the air filter assembly and it seemed to push exhaust out the air intake when it died.. I'm beyond confused but I dont want to send the mower off to a scrap heap when it seems to have good compression, and works well while it's running... does anyone have any thoughts?
It’s possible the fuel tank is not venting. Try to remove the gas cap when it acts up. Also check valve lash ...looks like the only area you didn’t cover.
The instant it stops, toss a little fuel down the carb and see if it fires up
Yes = fuel supply problem.
Either a blockage in the tank vent as previously mentioned or the tank outlet gets plugged from floating debris.
So I checked the valves today, they are in spec.. tightened everything up and tried it again.. with the same results. Can an engine lose compression after it’s cranked? I would think it would always have the symptoms if it was low compression. Maybe I’ve missed something with the carb.. I’m so stumped by this mower. It did however have a lot of carbon built up on the piston head. Is there anything I’m missing? I’ve ran it without a gas cap and it still dies.. maybe I’ll change out carbs tomorrow with one I know works..
So I took the air filter housing back apart today, jumped the mower off and when it started dying I did as you said and it started running right as long as I supplied fuel. That made me wonder if the fuel line had issues so I removed the gas tank and fuel line and unclamped the hose..and no fuel ran out. It had a clog where the nipple feeds into the rubber hose that wasnt aparent until you took the line off. It was full of some rope like material. Cleaned it out, mower started up just fine and put everything back together. Let it run in the drive for around 45 mins with no issues and cut my back yard with it after. That fixed the problem!
Now if I can fix the troy bilt one I'll be happy. Thanks again man!
Unless you have small children who like to "help daddy" hen that ropey looking stuff is grass clippings that have partially decomposed and the water in them has been replaced by fuel so they sort of 1/2 float till the engine starts sucking fuel when they get drawn into the outlet with the results that your are now aware of.
None of the other stuff you have done will hurt the mower either as it is called maintenance.
And yes the next suggestion would have been to rig up an alternative tank or remove the fuel cap & blow back down the line from the tank side of the fuel pump.
But it looks like you worked that one out by your lonesome .
Thanks for coming back with the results.
It is a massive help for the lurkers who seek answers without posting.
