Twin 4.3L Merc's

[eastont]

Ever since I bought the boat 3 years ago, the port engine has been using way more gas than the port. I've swapped carb's and it's still the same, altough a bit less. I've had the valves done on 2 cylinders and still the same.
I just came back from a 2 wek trip and the port engine used 115 gallons and the starboard just 82.
The mechanic seems to be at a loss as to why, and because of the contract I have with the place I dock, I have to use thi particular marina.
A guy I met during my trip, who is a car mechanic, suggested the timing chain....when I mentioned this the marine mechanic said he checked that last year.

Any body got any thoughts

 

[mkast]

Re: Twin 4.3L Merc's

suggested the timing chain

I would like to hear that explanation.

Start with basic engine diagnosis.

 

[mastercylinder63]

Re: Twin 4.3L Merc's

Greetings, I had the same problem. Assuming that both engines have new plugs,wires,etc. Check your timming. My port engine was off a few degrees. A few degrees off can make a huge difference in fuel consumption and performance. Once adjusted, later on recheck again and make sure it's still set where you had it.