SLT1550 runs fine 15 min then rough idle, then dies. Any help?!

[Bob Moore]

My SLT1550 won’t stay running. It’s worse when I engage the blades. I can start it and it will run ok for about 10-15 minutes… then the engine will start bogging and sputtering and die. I have replaced the fuel filter, fuel pump, spark plugs (properly gaped), carburetor, air filter, and oil filter! Can anyone help? I’m about to throw in the towel and chuck it!

 

[gary noblit]

Bob,I'm assuming the fuel tank is under seat...here's a thought because it sounds like you're running out of fuel.Unhook gas line at filter and blow back with air pressure.If the line is plugged partially that should clear it temporarily. I've found lots of unusual items in tanks,stones,toys,rags,sticks..It could also be a vacuum issue that tank is not breathing thru cap vent...

 

[Bob Moore]

Bob,I'm assuming the fuel tank is under seat...here's a thought because it sounds like you're running out of fuel.Unhook gas line at filter and blow back with air pressure.If the line is plugged partially that should clear it temporarily. I've found lots of unusual items in tanks,stones,toys,rags,sticks..It could also be a vacuum issue that tank is not breathing thru cap vent...

Thanks Gary! I have loosened the gas cap in case it is not breathing any more, but I haven't thought about blowing back through the line from the filter to the tank. I'll give that a try!

 

[gary noblit]

Bob,I have a small (2 qt) gas tank that I use to test systems . With long hose I mount it on steering wheel and hook it on fuel pump.Just a couple of cups of gas is enough to run quite a while without driving..Put a shutoff on hose!! 1550 is not that old but todays alcohol is sabotaging old hose lines.??

 

[tkhoffman]

I too was thinking a Venting issue. You disproved that.
Second thought was an issue I had with a new-to-me Push mower. 1 minute 47 seconds it would die. Scratch head, start again and 1,47 it would die. Issue was the carburetors gas Seat got soft and mushy and, although it was seating, the through hole was way reduced. The bowl runs down, Needle valve opens bit flow of gas could not keep up with demand. Bit you say you replaced carburetor?
Ok, maybe look at Coil breaking down as it gets up?

 

[manthony]

I had a push mower that would would get weak and die when hot. After a cooldown it would run fine for a while. Turned out to be the exhaust valve clearance was too small when cold, and when the valve got hot, it lost all clearance, and was held off the seat.

 

[Patrick Ferguson]

Renew your Condensor , that schould do it !