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· Old Squeezer
22,617 Posts
Discussion Starter · #1 ·
I bought a used 1984 Mercury 50 hp serial #6540604. It surges at high speed and never really runs wide open. According to my repair manual it is probably one of the fuel pumps.

My question is this thing was built before ethanol. Now ethanol is in everything. To make this motor dependable what should I update? I'm going to rebuild the fuel pump with a kit. How much more do I need to do? Fuel lines? I don't want to get stuck somewhere. I've tried 89 octane, 91 octane, and 93 octane and no real difference.

Thanks in advance for any and all advice.
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