I have an old 5 hp Sears Gamefisher. I can get it to start, but it runs rough. If I play with throttle speed and get it just right, it will suddenly smooth out and quickly increase RPM's, then suddenly die. Gas is clean, and in-line filter is new. I tried elevating the gas tank to see if it was a fuel pump problem, but there was no change. I bought this used with a boat a while back, so I don't have any history on it.
Now the kicker - I don't want to put much money into this old motor, but would rather get this running than buy a new one. I'm pretty good mechanically with replacing parts, but a poor diagnostician. Is there someone on the Waxahachie end of the metromess that I could take this to without spending what the motor is worth? Maybe what I need is somebody who would charge me just for a diagnosis? I'm leaning towards rebuilding the carb but I would hate to go through that if it's not necessary, and I'm just guessing. Any ideas?

As usual you should do a compression check, if OK then, carb cleaning and rebuild, and minor tuneup, and water pump. Then if it still doewsnt run its probably electrical.

The above is just normal maintanence.

it sounds like the carb is running out of gas.. thats why it leans out and shuts off.. make sure the tank vent is open and allowing air into the tank... if the vent isn't open it can vacuum lock.... rebuild the carb and make sure the float is set right...if this is an old air cooled motor a lawn mower repair shop might be able to help you or get parts...good luck

this motor uses a fuel mix of 25to1 not 50to1 could be leaning out check the vent in the gas cap if needs carb kit most parts are around the blader valve in carb is the only part hard to find they stoped makeing it about 12 years ago good luck mike

Thanks, guys! The gas tank vent is open, and I bought a copy of the owners manual. It says to use 50:1. It is water cooled, and sprays water fine. According to the Sears website the bladder valve is available, so I may be in luck there. Someone recommended a guy in Duncanville, I may swing it by there and have him look at it. I don't have a guage to do a compression check.

go to wallmart get a can of B-12 in automotive
get to the carbuters while motor is running spray B-12 in carbureters. dont spray much at a time or motor will die

Justin

do not spray b12 in motor while running cemtool has no oil in it you will have a trotline weight in a heart beat, make sure vent is not stopped up check for water in fuel are you useing remote tank or built in

if you dont spray b-12 in carb while running motor will have a hard time starting if starting. because the ratio will not be right.

Andy at DFW Boat Repair.com has quickly convinced me that my best bet is to take it to him. That is great, as family medical problems and work has suddenly made inroads on my free time. Thanks for all the advice, I'll try to remember to post the results so you guys can see how close you came to the solution.