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1999 Ski Nautique has 1017 hours on it. New to me this year. Runs fine but has an intermittent very hard long crank start with multiple cranks required. 90% of the time it fires right up. Can be problematic when hot or cold. No codes on the ECM. My compression is at about 90 across all cylinders. Is it time to rebuild it? Is the ECM going bad? I've replaced everything in the manual under hard start issues. Fuel pressure at the rail is 39 psi. When I look up the Ford 351w everything says compression reading should be around 150 and under 100 is bad. Can others share there numbers? I'm in Denver so I will have a lower number anyways. Bumming me out if I need a rebuild at such low hours when I see others at 3000 hours. Was hoping for one more big season but sick of the random hard start.
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90 seams low to me the fact they are even is a good sign . How are you doing the compression test? All plugs out and let it pump 4 times per cyl? -
All plugs out, throttle all the way back in neutral to open flapper in air intake, ignition coil disconnected. Turn about 4 times or until I see the gauge stop progressing up. Engine is warm.
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Did some research and test on a 2001 GT40 with 500 hours. I think 150 is a good new number at sea level.
Elevation multiple newmotor
Sea 100 150
1000 .9711 145
2000 .9428 141
3000 .9151 137
4000 .8881 133
5000 .8617 129
6000 .8359 125
7000 .8106 121
8000 .7860 117
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