john deere 485x wont start when hot

bill finn

Member
my sister and brother each own a john deere 485x. they both are experiencing a no start after an hour of run time during summer heat. Not so much in the fall of the year. My brother claims he removes the air cleaner and cracks the fuel cap and it cranks a bit then starts. My sister gives it an hour to sit and hers runs. Does anybody have an idea what would cause this?
 
If I could crack the fuel cap and it seemed to help the situation, I would replace the cap.

You also need to check for spark when they refuse to start.
 
Could be vapor lock and probably at the fuel filter. When it happens again, get a can of starting fluid and remove the air cleaner giving the carb venturi a good dose while you crank. If it lights right off you have your smoking gun.

The fuel line runs right by the crankcase on most mowers and sucking on a hot fuel line (carb venturi vacuuming) lowers the barometric pressure within the line. Reduced pressure causes most anything to boil at a given temp especially a volatile liquid like gasoline. You can make water boil at room temp at vacuum atmospheres.
 
I HAVE A 425 JD DONE THAT IT HAS A FUEL SHUT OFF i SHUT THE FUEL OFF FOR ABOUT 30 SECONDS BEFORE I TURN OFF THE KEY IT WILL START RIGHT UP I HAVE TO KEEP THE SIDE OF THE TRACTOR OFF TO GET TO THE SHUT OFF THE CARB PULLS IN GAS AFTER IT IS SHUT OFF AND FLOODS IT OUT MIGHT TRY IT BEARS BUYING A NEW CARB
 
might want to check fuel pump pressure . Those injectors need the right amount of pressure or the computer can't correct the fuel delievery .
 

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