1997 Baja Islander 272, 502 magnum fuel Injection problem.?

Question

I can not get my boat faster than 40mph @4500rpms and usually it goes between 63-68mph @ 5000rpms depending on how much gas and people I have on board. I already took my boat out of the water and drain the water out of it and put it back in to see if it was water weight slowing me down, but it wasnt and still the same results. I take off fine and then when I plain out it wont go any faster. It doesnt sound like the engine is missing, I did ck the spark plug wires any way to make sure they were all connected. Any other suggestions on what is making my boat run slower??

Answer 1

okay, it gets tougher from here.  should probably take it to a pro.  you could have one injector clogged.  what is the fuel pressure?  is it firing on all 8?  a diagnostic computer (DDT) can troubleshoot it in a few minutes.

Answer 2

500 rpm should not increase your overall speed by 23-28 mph.  5000 rpm sounds a bit excessive for a 502. Did you check throttle linkage for WOT.? Fuel pressure, fuel filter?