2018 DF140A lacking performance

[kirk35]

Hi all, I'm a new Suzuki owner and need some help diagnosing what I feel is a problem. My dealer doesn't seem to be much help as they don't think there is anything wrong.

The boat is a 2018 Robalo R200 with a 2018 DF140A. The boat struggles to get on a plane and has no top end. After a few test runs these were my results.-----------> R200 Suzuki DF140A.pdf

This is the same boat with Yamaha engines----------> R200 Yamaha F150XA.pdf R200 Yamaha F115XA.pdf (only comparisons I could find for this exact boat).

The big difference I have found with my boat compared to any other DF140A tests I have read is that my fuel flow rate is 8.5 GPH at WOT compared to 12 GPH +/- for every other DF140A in the world.

I dropped the boat off at the dealer Monday morning and explained the issues to them, suggesting throttle linkage or a restriction in a fuel line. I do not believe this is a prop pitch issue, since it doesn't get out of the hole or have any top end MPH. It is more of a lack of power. Fuel flow is in line with a DF90A, and it feels like power is too.

I stopped by the dealer again this afternoon and was told that the throttle was barely out of adjustment, "not enough to make a difference" were the exact words. The service manager told me the tech took it out and the boat planed in 6 seconds and topped out at 6,300 RPM's @ 9 GPH. They couldn't tell me what speed they achieved, as "RPM is all that matters". According to them there is nothing wrong and the fuel flow rate isn't an issue, because they got it to 6,300 RPM. My guess is they had the motor trimmed high enough to get the prop out of the water.

I'm going back tomorrow morning to put it in the water with the tech from the dealership, but I think I'll be left figuring this out on my own. This is where I could use some help from someone familiar with Suzukis. Is my assumption correct, that I cannot be achieving full power while only burning 8.5 GPH? Can anyone with a DF140A let me know their fuel flow at WOT?

Any help would be appreciated!

[Moonlighter]

Wait till you can test it again.

If indeed the motor will now pull 6300rpm at WOT, with a light load, it seems that the prop selection is pretty good and not too much can be wrong.

There is no point at all doing those rpm/speed/economy tests with the engine trimmed at anything other than the optimum - in other words, you start with the engine trimmed in so the boat gets onto the plane as quickly and easily as possible, then as she rises onto the plane, trim out until the optimum position is achieved, and finally, stick with that trim as you record data up to max speed, and finally, for the WOT test, trim out until the engine loses grip, then trim down a touch so it grips again.

An important question : What is your source of data for speed, fuel flow and fuel economy?

8.5 does sound low, on Australian boat tests at WOT we see most results at 6200 around 11.5 to 12 gph.but it depends on where you are getting that fuel flow data from as to whether it is accurate or not.

[kirk35]

Speed comes from GPS, fuel flow from Suzuki C10 gauges, fuel economy is a calculated value from speed and fuel flow.

I'll probably be bringing it home from the dealer tomorrow. Assuming the Suzuki gauges are correct, what do you make of the WOT flow rate?

[Moonlighter]

Too many assumptions at this stage, wait till you see how it goes when you test it with the technician - if it achieves 6300 @WOT, then it is hard to see how there could be much wrong.

Lets not get too far ahead of ourselves here - the dealer might “say” that not much was wrong, but they may have done something that makes a significant difference when you actually test it for yourself. (Check the prop when you get there to see if they have changed it!)

Sometimes, there are issues with reported fuel flow rates on the C-10 due to conflicts between C-10 software and the Suzuki interface. If it is still reading low, there is only one way to check and verify, and I can explain that for you later if required.

[kirk35]

10-4. Thanks for the response, I'll post the results tomorrow after I've had a chance to run it again.

[kirk35]

Too many assumptions at this stage, wait till you see how it goes when you test it with the technician - if it achieves 6300 @WOT, then it is hard to see how there could be much wrong.

Good advice! We put it in the water this morning, I idled out to the channel and as soon as I pushed the throttle forward I could tell a difference. The boat planed in half the time as usual and I was able to achieve 38 MPH @ WOT, 6300 RPM and fuel flow was 11.7 GPH.

The tech that worked on the boat was with me and he swore all he did was make a 1/4 turn adjustment on the throttle linkage. I find it hard to believe that was all it took, but it literally feels like another boat.

[Moonlighter]

Excellent!

Now, go fishing and enjoy! We expect to see photos added to the sticky thread at the top section of the forum in a short time!