So blew my starboard 525sc apart (two rods right thru the oil pan and block cracked) in may.... this past weekend finally got her back in the boat and got everything set. I cruised around at 3000 rpm and pulled the plugs and they looked fine. Fuel pressure was about 5-6lbs on both sides on the gauge. so i brought it up to 4000 and pulled the plugs again....no sign of detonating but running on the leaner side....Fuel pumps were replaced in 2009..... should i switch to a high flow pump??? throw a gauge off the fuel pressure sensor off the carb??? any ideas would help......

Beginning of the season, our mechanical pumps weren't able to keep up so we threw a block off plate over both ports and switched to Holley electric pumps. If your sticking with mechanical pumps, I know Jeggs and Holley make a good 110 gph pump.

Is your fuel pressure dropping or do you just have a lean condition? If fuel pressure is dropping at the higher rpm's check the fuel pick up in the tank to make sure it doesn't have a blockage in it.

it leans out at just over 3800 rpms. the plugs look a bit white. no blistering on the electrode though. the fuel pressure on both engines shows 4-5 psi (which seems low) and as i get up to 3500-4000 it drops a lb or 2. the port motor plugs seem fine though.

You should have 8lbs. I ran two lines off separator; one to feed the mechanical and the other to feed an electric pump and "T'd" them at the outlet port of the mechanical pump and then to the carb. This will keep them fed nicely.

You were given bad advice to switch to those electric pumps. There are many fool proof mechanicals for that setup. Need to see if you're running lean because of a fuel pressure or tuning.

fresh fuel filters

any recommendations for a good aftermarket pump??? no way im going back to stock merc pumps cause all ive herd is they're complete junk and last 2 yrs.....

I love my CV billet pumps. A little pricey but rebuildable and adjustable pressure also.