I have a craftsman 15.5HP Riding Mower 42" Deck - 917.256524 - build date from 1996 that is giving me some troubles. Two cuts ago it began to run a bit rough, and it had the original carb, so I pulled the old one, with the fuel lines and purchased a replacement, added a new fuel filter and it fired up and ran like a champ.
HOWEVER - now it's time to get another cut in... it's won't start. The mower will turn over when choked and combust... but then dies almost immediately. I checked the seat switch - which seemed fine, but no matter what throttle setting does it run. The engine is getting fuel, the plug isn't fouled.
I'm at a total loss of where to check next. Any ideas?
Start by checking the choke control is sitting in it's correct position in the throttle control plate.
It is very easy to fit it under the slot it is supposed to run in. Have done this more times the I am willing to admit on a public forum.
Check for water in the float bowl.
Idle fuel is drawn from near the top of the bowl but full speed running comes from the bottom and sucks up any water that may have accumulated there.
Next is to check for air leaks between the carb & the mower.
From memory you should have an O ring between the manifold & the engine which should be replaced every time the manifold is removed as they rarely reseal properly
As you have reciently replaced the carb there is a better than avarage chance on of the carb mounts has worked loose which will also allow air to get in resulting in a too lean situation once the choke has come off.
Thanks for the items to check! I went through all of the gaskets, and still nothing. I checked the carb's solenoid, and it appears to be behaving properly as well.
It'll crank, catch and then shut off maybe 3-5 seconds later. What else could there be?
Don't knock yourself out over thinking it.
Start by checking if it is really a fuel problem by squirting some starting fluid down the carb,
If you can keep the engine running by squirting LITTLE shots of starter fluid every couple of seconds then you have confirmed you have a fuel delivery problem.
Second test is to pull the fuel line off the carb, and place it in a jar . It should be full of fuel and fill about a cup in around 30 seconds..
If not remove and clean out the fuel tank and fuel lines.
Check that you have a gravity feed fuel filter fitted and not a pump filter which is a bit finner and can slow down fuel supply.
Finally it will be off with the fuel bowl and check you have a strong flow ( stream ) coming from the float valve and not a dribble.
If that is OK remove the main jet and check it for debris.
If the old lines were in bad condition you can get little bits of rubber come loose and block things up.
