90 hp yamaha precision oil inj stumbles after 10 to 15 sec

arkboater79

Cadet
Joined
Jul 11, 2011
Messages
6
Just got a bass boat with a 90 hp yamaha. Took it out and it ran fine for about 15 to 20 sec then started stumbling and sputtering. Turned off motor and let sit, started and run good wide open then 15 sec later, stumbles and rough running if you increase throttle but seems to run fine at low rpms.I changed spark plugs thinking they were fouled but no luck. New fuel line.I pumped bubble while acting up with no change, tried slight choking but doesnt help. Wonder if fuel pump may be bad,or bad coil, any ideas. I thank you for your input.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Re: 90 hp yamaha precision oil inj stumbles after 10 to 15 sec

Wrong section.But try first:compression/spark test.Then rebuild fuel pump.Check for water in the gas.J
 
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