Mercruiser 5.7 misses under load

[nvanzee]

Have an 01 rinker with a 5.7 in it. It misses under load and seems to be lacking power. It doesn't miss horribly but it does miss. Once it's on plane it's not too bad but still seems to be about 15mph slower than it used to be. I know a bit about engines but not so much about carbs and I'm at a loss. I have replaced the cap and rotor, along with plugs and wires within the last two years. I've checked timing and it's sitting right at 10.

It did have a mild cam put in along with an intake a switched to a 4 barrel carb 5-6 years ago.

If anyone can point me in the right direction of what to do next it would be greatly appreciated.

 

[Scott06]

Good the ignition components are new. I would check inside the cap that there isn't corrosion to rule that out. Additionally I would check that you are getting 28 or so degrees advance by like 3000 rpm.

have you checked tge contents of the fuel filter for anything but good clean fuel? If fuel is clean, check you have 4-6 psi to the carb while running. If these check out gave the carb cleaned and rebuilt. Most likely the carb has some dirt in the passages but you want to make sure you are delivering clean fuel before you rebuild it.

 

[Scott Danforth]

Agree with Scott. Look at your fuel system