2017 DF140A Bogging Down

[D'oh999]

Hi All, Thanks in advance.

So my DF140A appr 300 hrs runs great for 5-15 minutes @ 4500 RPM, then it will bog down 3800-4000RPM, like fuel starvation. Pushing the throttle only bogs it worse. Back off on the throttle and punch it again, it works great, for a period or maybe the whole trip.

No External Filter/Separator, but I did replace the Motor's sediment bowl filter this spring, last year I noticed some hesitation on accelerating (thinking Fuel Starvation then too).

Then, this year I had the Primer Bulb (never used) fall apart inside, plugging the fuel line. Diagnosed on the Lake after bobbing for some time on the water. So, again I am thinking Fuel Starvation.

Boat has EPA Closed Fuel System (BS) so I thought maybe the Tank is over full, and a Ball was plugging the pick up. No t it, The Primer Bulb isn't sucking flat.

So, then I get to thinking, maybe it is dropping a cylinder? Trying to tell if it is on 3 instead of 4. It is possible, but wouldn't it throw a Code?

What are your thoughts? VST Filter? Try running it on an external tank? (no signs water in fuel) Run the same fresh gas in everything and add 15L every week. Fresh Spark Plugs?

[Moonlighter]

First, you are crazy not to be running a separate Racor style water separating fuel filter between the tank and the engine. That should be the first thing to do.

Given the history theres a fairly good chance that the fuel system is contaminated. VST clean and probably change the (expensive) high pressure filter too.

[D'oh999]

Thanks for the thought on the Separator, Never ran one on the last boat for 20 years and it burnt more fuel. All inland lakes, Fresh Water, trailered so no marina fuel.

I would almost bet that another piece in the System would stand as much chance of failure as not having it. Especially now that a "Water in Fuel" sensor is in this system. be it only a couple of ounces vs several.

I just think I am missing the Obvious. The VST Filter being the last resort, as the Primary Filter has never left it's spot, so tough for any debris to get to it. Primary Filter is New and Looks Clean, installed correctly, well seated, Factory Suzuki Part also.

I am tending to believe it is a EPA Boat Fuel System issue.

Or maybe a Fuel Pick Up issue.

I have to recheck that Primer Bulb while it is happening, and maybe even swap out the Primer that I replaced

[artdf175]

3800-4000 rpm is not the normal range when something fails which is 3000
do you have the engine interface cable installed to pick up engine fuel usage/rpm/ temp on a MFD?
if so I suggest to disconnect it and see if the problem persist..
This was a problem I fought for 2 years. discovered it watching the rpm on my MFD The rpm would peg then drop to zero back to normal .. the analog rpm gauge would not pick up the spikes.. It was the spikes that caused the rpm drop. this is not in the repair manual but I watched enough to figure it out..
One other observation -- in-line small fuel filter-- do you see any air bubbles appearing? It should be full with no air.. If it getting air bubbles then you would have an air leak in the fuel hose someplace between the tank and the low pressure fuel pump.. eventually at higher rpm you burn the fuel out of the VST.

Art

[redlowrey]

Before you spend a lot of time and money, replace the plugs, a single cylinder misfire will do what you are describing. They changed the design of the vst instead of having a small inlet screen they made it a large screen and done away with the high pressure filter.