intermittent hesitation, need help, on holidays

[chief351]

1990 SN with 351, 500 hrs. Skiing for the past week, everything working excellent. Last night the motor started to hesitate when pulling a skier out of the water. Motor felt like it was labouring to reach 34 mph, once at 34 mph the motor would feel like it was cutting in and out very slightly. Once last night while cruising at 34 with a skier in tow the boat accelerated a few mph and felt like it was back to normal (probably accelerated to 38 or so mph), this occurred with the throttle in the same spot . A few minutes later with a new skier the same hesitation appeared when accelerating. I checked my top speed with my Garmin GPS and it was about 38 mph, typically I get 43 mph top speed. After running at 38 mph for a few minutes the engine felt like it unloaded and "freed" itself up and shot to 43 mph without a hiccup. However I slowed the boat down and tried to accelerate and the hesitation reared its head again. I am half way through a fresh tank of 91 octane fuel. I have checked all the spark plugs and they appear in excellent condition as do the plug wires (almost new). Everything else works excellent.

Any suggestions would be appreciated.

Thanks in advance
Chief351

[MHayes]

RE: intermittent hesitation, need help, on holidays

I'd also check the fuel filter to make sure there is nothing restricting the flow and the next step would probably be the fuel pumps.

[chief351]

RE: intermittent hesitation, need help, on holidays

Thanks Mhayes. Is the fuel filter and the fuel filter/water separator the same thing? Or are there two separate pieces of hardware? I used the drain plug on the bottom of the fuel separator and drained out some dirt/water/gas. I just ran into town and got new spark plugs and changed them but the hesititation is still there. Off to check the fuel pump somehow and the anti siphon thing in the tank. Any other suggestions are appreciated.

Thanks
Chief351

[chief351]

RE: intermittent hesitation, need help, on holidays

Ran 25 gallons of gas through the ole girl and she is running like a champ. Must have been water in the gas. Anyone know the water/fuel separator filter # off hand? Preferably in the WIX line.

Thanks