Twin outboards unequal fuel consumption

I know this thread is old but I too concur my starboard engine uses more fuel. I also need to push my starboard throttle farther ahead of the port to get the same rpm. Also, the starboard engine has a top rpm of about 5800 when I'm trimmed for top speed, my port engine will hit 6100.
 
matt_unique":s5q6e1mq said:
I know this thread is old but I too concur my starboard engine uses more fuel. I also need to push my starboard throttle farther ahead of the port to get the same rpm. Also, the starboard engine has a top rpm of about 5800 when I'm trimmed for top speed, my port engine will hit 6100.
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Hmmm? Since I've had the carbs rebuilt on my starboard engine (twin Honda 45's on 22 Angler) my starboard engine uses about 10-15% more fuel than the port engine. I didn't run them enough to see if it did this before the carb rebuild. The starboard engine also needs "less" throttle movement to match port rpms, but I atribute this to new cables that I installed...needing adjustment.
Even more strange is that I typically run the port engine more! The starboard still doesn't want to idle at times, and often dies when I throttle back to idle, so I'm in the habit of moving away from the dock, or approaching the dock, with only the port engine.
 
I have the twin Honda 150's, but only notice a very small difference in fuel consumption at slow cruising speeds, i.e., hull speeds of 4-9 mph. My last fill up showed about a 12% greater fuel usage by the starboard motor. However, there could easily be a difference in how rapidly the fuel nozzle is shut off.

I start off and end each cruise with 30 min. or so of high speeds, so not always going slow, though. I use the autopilot extensively and it groans back and forth at times.

I do have the same difference in top rpms reported above. I keep the Permatrims pretty well flat most of the time. The steering for the engines looks to me as though they are often "toed in" or not exactly parallel. This seems to be worse at slow rpms - hull speeds.

Does anyone know if the engines not looking parallel is a sign of SeaStar steering problems? ... installation? ... or normal operation? ...or low fluid? ...or air in lines?
 
Just another piece of information to add to the above:

The Suzuki 150 motors now have excess of 250 hours. Last week we took the boat down from Clear Lake to Corpus Christi. Full gas, full water, full provisions, two adults, bimini, permatrims, Texas flag on top of the cabin, ensign on the stern, bottom paint.

After a non-stop 107 mile first leg at 28-31 mph, fuel economy (judged by refilling the tanks) was exactly 2 mpg.

The starboard tank took only 6% more fuel than the port tank. In fact, the difference between the two motors, while still significant, seems to be gradually declining as the motor hours are increasing. Either I am getting better at trimming the boat, or the counter-rotating gear is running more freely...
 
Dick,

Are you able to get the same RPMs on both engines at WOT? If not, I would check out the pitch on both your props. When I ordered a spare set of props from the Prop Gods, I paid extra to have the props checked out and balanced right out of the box. One prop was 3/4" different in pitch.
 
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