2015 DF175 surging

[stephendudra]

I have had the engine installed for a year now and maybe 30-40 hours total on it.

Yesterday while cruising, it started surging at higher RPM's. I cleaned in line water separator and that might have helped a little. It continued to do it and would only rev to the low 5k RPM's range.

Anyone seen this and have advice before I take it into the shop?

My thoughts are the high pressure fuel filter.

It is under warranty, but I do not know if the warranty covers this or not.

Any and ALL advice is welcome!

Stephen

[artdf175]

almost sounds like it is starving for fuel
is the fuel pump bulb semi-collapsed?
one of the other problems is tank venting
another issue has been some type of a back-flow system that has created what sounds like a partial fuel blockage

maybe other can elaborate on the last point..
Art

[Harper]

Go ahead and take it in to the shop. It's hard to say just what's causing this, but it sounds more to me like a throttle position sensor maladjustment or the sensor itself acting up. And it's probably going to take a diagnoatic hookup to pin it down.

[Solarman]

It does sound fuel related, but i'm thinking regulator, or one of the check valves related to HP fuel pump flow rate. Unless, the low pressure pump is failing to keep enough fuel in the vst for the HP pump. And yes, there could be a restriction before the low pressure fuel pump. for example, read the next paragraph.

I know moonlighter will tell you to check the anti siphon valve at the fuel tank, and yes that is a very possible cause.

The shift position sensor would be my call if you could only get it to 3k RPMs.

Oh how complex these 4 strokes can be, lol.

I agree, take it to the shop, but let us know what's up. Good luck

[Moonlighter]

Actually, I was going to suggest the simplest thing first: change the water separating fuel filter element!

(Anti-siphon valve problems tends to cause stalling as the boat slows back to idle speed after running along at cruise speed. So I don't think that's likely to be it this time!)

You've mentioned already that you drained the water separator and that helped a bit. All it takes is a dirty load of fuel and that filter could be clogged, restricting fuel flow to the engine. That would be my first option, a new filter. Had the same thing happen myself a few years ago and that sorted it. If that does fix it, not a bad idea to change the filter again after another 20 hours in case more rubbish is in that tank.

Next choice would be as Art said - check the tank vent to make sure it's breathing fine, and that nothing (eg one of those mud wasps) has made a nest in there and partially or totally clogged the vent.

(PS by the way, I've reported the spammer on that unintelligible post that went up a short while ago. If a few others also report it we might get A D M I N attention to get rid of it)