300/440/550 Runs for an hour then starts to bog

L

Lando.jetchris

Location
Utah
Bought a 1987 Js 550. It runs great for about an hour then will start to bog (more of a lean bog) . Almost like it fouled a spark plug but next time i go to the lake it runs great for another one then craps out. Usually work on four strokes. Any advice on the ski?
 
J

Jiffyjet

Location
California
Lando.jetchris said:
Bought a 1987 Js 550. It runs great for about an hour then will start to bog (more of a lean bog) . Almost like it fouled a spark plug but next time i go to the lake it runs great for another one then craps out. Usually work on four strokes. Any advice on the ski?
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Fuel tank vent clogged or in backyard ?
Maybe coil starting to go when hot?
 
Myself

Myself

manic mechanic
Location
Twin Lakes AR
Ok, you should pull the fuel pickups out of the gas tank. Submerge in a bucket of water and blow air into where the fuel lines hook up. I've seen several that have cracked near the top. As soon as the fuel gets below the cracked area it sucks air into the line causing lean running and bogging.
 
L

Lando.jetchris

Location
Utah
Myself said:
Ok, you should pull the fuel pickups out of the gas tank. Submerge in a bucket of water and blow air into where the fuel lines hook up. I've seen several that have cracked near the top. As soon as the fuel gets below the cracked area it sucks air into the line causing lean running and bogging.
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it had cracks, got them fixed, runs great now
Thanks wouldn’t of figured it out myself
 
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