LM318 Purrs like a kitten at the dock.. but then

[Dollarbill]

In the dock: Starts right up. Sounds great. Idle's smooth. Run up the throttle - sounds great. 3000 RPM smooth and sounding good. Water pumping a nice stream. some exhaust smoke in the stbd engine like it may be running just a tad bit rich maybe . Nothing bad.

On the water: Put the boat on any load past 1000 RPM and it sounds and feels rough like it is only firing on 2 cylinders. Backfires in port engine around 2200 RPM. Just a nasty experience. This feels like both engines.

Where should I start first?

Anybody know of any good Chrysler mechanics on Lake Lanier north of Atlanta. These guys around here dont like to work on anything but Mercruiser.

Thanks for your help

 

[fastjeff]

You need to do the wire pull test.

To wit: Idle at 1,000-1,500 warmed up. Using insulated pliers and heavy gloves, pull then replace one wire at a time from the distributor cap and listen to how the motor slows down. If it doesn't slow down leave that wire out (then find out why it's not working). Revealing test!

Jeff

PS: One of my engines sounded great as well--and planed the boat off just fine--but had two wires switched. Easy to do with the dopey way the wires are run from the factory.