Suzuki DF250 2014 losing power and surging

[Starcees]

Hi there, I have a 2014 df250 that I have owned for a couple of months. The motor has recently been serviced by. Qualified mechanic, since service I have been on several long runs with no problems. Yesterday I experienced power loss and surging at all power settings this was noticed about 30 mins into the run. Fuel consumption went up significantly also. Thankfully we got home in one piece. Initially I thought this to be a fuel related issue. Today I lifted the cowl and noticed oil was coming out of the valve cover breather hose I checked oil level and it is way over the full mark on the stick. It’s important to note the oil level has been high since service and I thought this ok because it was serviced by mechanic. Just after some thoughts, I’m thinking engine has been breathing oil vapour affecting mixture, plug fouling etc. It high oil level a correct diagnosis of problem?

[aquamort]

Mate it looks like your needle and seat in the VST is faulty. I'd guess the oil smells like fuel? Would explain the poor running, excess fuel and making oil syndrome. Not a hard job to do if your mechanically minded. Would not think it had anything to do with your mechanic?

[Starcees]

Thank you for your response. I’ve since had it on the computer and all looks good. I now know we had a low fuel level also to confuse the issue. Low fuel occurred because it’s a new boat to me so I’m unfamiliar with the fuel levels. Also there was no manual gauge only computer data, my interface cable had been the wrong software version and I think it was under reporting fuel usage. Thanks again.

[aquamort]

Engine wont normally run bad because your low on fuel...unless your actually running out of fuel? Running well now? What about the excess oil?

[artdf175]

I think your last question was answered above
Can I assume you had checked the oil after the engine was serviced? And now are finding it overfilled?
Pull the dip stick and smell the oil- does it smell of fuel?
If so it will need to be changed
the reason is usually the float valve in the VST (high pressure fuel pump) is out of adjustment. Usually.
Art

[Starcees]

Thank you for the reply. The oil doesn’t really smell of raw fuel. I am going to take it for a run next weekend and see if I can work out what’s going on. The fuel tank level was low and now I’m wondering if it was sucking air in the rough seas.

[Moonlighter]

With oil level “way over” to use your own words, I would personally NOT be running the engine again until the reason for that situation is identified and rectified. You risk doing real damage to the engine if that oil has been significantly diluted by fuel. And unless its milky indicating water, the only other thing that can get in there to cause a increase in volume is fuel.

Some of the engines have a vapor tube that runs from VSR into the crankcase (for EPA reasons) and if the VSR is clogged or needle not seating, raw fuel runs into the case. If you can find that tube, and start the engine un the muffs, pull the tube out and see if fuel drips out. You then know the cause and can act to correct it.

[Starcees]

That’s great thank you good call.

[Starcees]

Ok thought I would give an update that, fingers crossed will close out my issue. Firstly the engine oil wasn't high, i've had it checked by a suzuki mechanic and it was me being pedantic. I do apologise as this has confused the issue. Once the high oil had been ruled out we worked through step by step to locate the problem. First thing we did was check the primary fuel filter (only 10 hours old). We found the filter contaminated with congealed water and some red dirt. Secondly we moved down the line and checked the low pressure filter, we also found congealed water and dirt. Thirdly I drained the VST, fuel was clear. Curiosity got the better of me so I removed the VST, opened it up and examined inside. What we found was about a teasspoon of what looks like dirt or possibly old congealed water. The VST was thoroughly cleaned, reassembled and installed back on boat. As a final measure the High pressure filter was replaced. The design of these VST's means that any contaminants that are in the VST will be channelled towards the high pressure pump filter screen and block the pump pickup. The motor now runs perfectly with no power loss. Firstly the pickup design is poor on these VST's and probably others to. I can't change the design so as a prevention I will be checking filters and emptying regularly. Keep the tank full to reduce potential condensation, and treating fuel regularly with F10 to reduce moisture globules in the fuel. Thanks for all your input, great forum that I will be following regularly.