Mower acts like it has fuel delivery problem.

[Ol' Fart]

My Craftsman 917.289900 with Kohler 26hp Courage has been surging lately, both at idle and under load. I have replaced fuel filter, plugs, checked fuel pump and carb and all seems to be good. Today I was mowing the lawn and the mower sputtered once, then died. I restarted it, ran for a second, then died. Seemed like it was out of fuel, so I checked filter and it was full so I pulled off the gas cap to make sure fuel in the tank, there was. I started the mower with the cap off and it continued to run, so I put the gas cap on, but didn't tighten it all the way. I finished mowing the yard and noticed the engine didn't surge. Now for my question, the gas cap appeared to be vented on the inside but I couldn't see any vent hole on the outside. Would a blocked vent cap cause the surging conditions and engine shutting off as described ?

 

[Scrubcadet10]

surging is caused by a lean fuel/air mixture, meaning either MORE air than fuel, or Not enough fuel. so yes a clogged gas cap could cause it in theory because it can reduce the amount fuel entering the carb. usually people replace the cap, or like i've done drill a hole with a Micro drill bit.... cant remember the size off hand.

 

[Ol' Fart]

surging is caused by a lean fuel/air mixture, meaning either MORE air than fuel, or Not enough fuel. so yes a clogged gas cap could cause it in theory because it can reduce the amount fuel entering the carb. usually people replace the cap, or like i've done drill a hole with a Micro drill bit.... cant remember the size off hand.

Thanks, I'll order a new cap. Probably time anyway as mower is over 10 years old.

 

[enigma-2]

I've found that theres often a liner inside the cap that can be pried out and the vent hole cleaned out.