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I have a 1992 Yamaha 150, 2.6L V6, carbureted.

On a recent excursion, I noticed fuel consumption seemed much greater than usual. Fuel usage is being measured by a fuel flow meter. I was only watching "fuel remaining", not the actual flow rate. Fuel remaining decreased much more rapidly than normal.

On this particular outing, we were not any more heavily loaded than usual. However, due to wind/chop conditions, we were operating at what I consider to be less than optimal speeds for efficiency - - slow planing speeds as well as no-wake speeds against wind and current.

Fuel consumption seemed to be nearly double what we normally would use for a similar excursion, at more efficient operating speeds. Could the less-than-optimal operating speeds double fuel consumption?

Due to a busy schedule, the boat hasn't been out much this year. Could the carbs be experiencing a malfunction?

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Do you keep the whaler on a trailer or in a slip? lack of use and a fouled bottom would increase fuel use.

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Good point. I should have mentioned that the boat is a trailer queen with no bottom paint.

I paid $4/gallon for 89 octane at the fuel dock. So maybe I was feeling overly sensitive to fuel consumption?

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JRP: I think the weather conditions you cited are enough to increase your fuel consumption. I used to run carbureted two stroke V4 outboards for many years and I was always amazed how thirsty the motor was when I encounter heavy chop accompanied by strong current. The fuel consumption was considerable when I cruised at less than an optimal planing speed.

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Okay, thanks very much for that feedback. It helps to put it in perspective.

We were operating in a largish river. The current speed was approximately 1.5 knots. This is a measured speed -- at one point when we reached a more sheltered (from the wind) area we cut the engine to drift while doing some birdwatching. I kept the GPS on while we were drifting and frequently observed the speed over ground for about ten minutes or more.

We also had bimini and dodger in full up positions. So it was a long slog upwind and upcurrent with a fair bit of windage deployed. At slow planing and fast displacement speeds.

I guess I was just looking for reassurance that I don't need to investigate a problem with the carbs. So far, you have me convinced.

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I have a fuel rate gauge on my rig and, having played with it a bit, I can assure you that your efficiency could well be 1/2 normal in the conditions you describe.

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Okay, thanks for the additional data point. You guys have me convinced that the increased fuel consumption I recently experienced can be accounted for by a combination of the wind, current, and inefficient operating speeds.

I will report back next time we get out and have the opportunity to operate the boat under more typical conditions and at more efficient speeds.