Is my Max II just sick? Or is it dying? Please help?

[Climbmax]

I purchased a '95 Max II 6 months ago with a 14 hp Briggs and Stratton Vangaurd. It tends to lose power and die while driving it(anywhere from 5 minutes to 1 hour). If I pull the choke out when it starts to die I can keep it idling but have no power to move. If I shut it off and leave it sit for an hour or so it starts up and runs fine, until it does it again. I cleaned out the fuel tank, replaced the fuel cap, fuel lines, fuel filter, and fuel pump. I have not touched the carb since I dont have a lot of experience working with them. Is there anything else it could be? I also noticed that the oil cap on the valve cover does not seal and leaks oil. Could the fuel pump lose vacuum pressure because of it? Any help would be greatly appreciated.

[JohnF]

I have not touched the carb since I dont have a lot of experience working with them.

No time like the present...

It sounds fuel starved, so I think you are on the right track. You might get away with running SeaFoam (look for it at the auto store) as I've had luck getting minor gunk out of carbs with it. But your problem may be carb icing; a particularly onerous problem because it melts away so that when you get to looking for it nothing will be there. Or water in your fuel in a really cold climate and an ice crystal has plugged a jet - the reason letting it set makes it work again is that enough engine heat moves through the carb to melt the crystal. (for that try isopropyl alcohol - a brand is iso-heat)

But this sounds like you've had this issue for awhile so I would pull and clean the carb. Think of it as an adventure.

[racerone3]

if your not comfortable with the carb rebuild, any lawn mower shop can do it. pull the carb off and take it to them. you will need to provide them with the engine model # and code (usually on a stamped metal plate somewhere on the engine tin) while your there get a new O-Ring for the oil fill plug. it could affect crank case pressure and therefore fuel pump operation. on the seafoam. it's great stuff. i run it in the fuel on all my small equipment. keeps the fuel dry and keeps from getting varnish in the carb. Motor Treatment - Sea Foam

[Robinhood02]

hi there , take off the fuel cap and run it for some time , if this fixes the problem then your breather cap is either pluged or damaged, some units have a little plastic screw in the middle of the cap ,make sure it is breathing , sounds like a breathing issue to me , if this don't work ,well, its back to the carb ,but i think takeing the cap off will do it <<

[Eldon]

Robinhood's solution is where I'm putting my money,definitely sounds like a vent problem.Most modern caps have a small hole in the gas cap that gets plugged,with dirt,rust etc..

[JohnF]

hi there , take off the fuel cap and run it for some time ...

This is a great idea; I would do the test a little different though, get out there and run it until it is fuel starved and then pop the cap and see if it is suddenly all better.

I would do this before I tried to unplug anything just so I was sure that was the problem.

[Robinhood02]

John has a good point and is probably the best way to check it, thats exactly how i discovered the problem i had on my skidoo last winter while out doing my trapping rounds ,my skidoo kept running out of gas but i thought it was fuel pump or filter ,just like you ,and then one time i figured that maybe i would take the gas cap off and check the gas , it made a sucking noise and all was well ,so once i got back to the cabin i took the cap inside to thaw out and things worked out fine adventures of the Great White North