Follow Up to earlier post - Oil in High Pressure Fuel Pump

[tjo716]

My 2007 4 stroke DF150 cranks fine but won't start. Checked all the obvious filters, used fresh gas, oil clear and full.

She ran great one day bad (idles for 1 min and then shut down)the next.

I drained the HP fuel filter in effort to address any vapor lock issues and it was a mixture of gas and oil.

How would oil get into HP fuel pump?

Thanks for any thoughts

[briscoe]

No additives to the fuel tank?

[briscoe]

I guess I should have said are you sure it wasn't an additive. The only way you can get something in the HIGH pressure fuel filter is from gas tank. It should have too much pressure for oil to back into it. When an engine cranks but doesn't start it narrows it down to fire (plugs) or fuel. I once got to the bottom of tank and it mucked up my injectors. However, it still started it just would not get up to full throttle. I always look at fuel first when it won't start.

[Harper]

I have a different perspective. Are you sure it's gas and oil? Seems to me the two would mix and the presence of oil in the gas would not be readily noticable. Are you sure it's not water and oil, which do not mix.

[tjo716]

Briscoe and Harper...thanks very much for your feedback.

Fuel tank was 50% full and gas about 6 weeks old.

Attached pic shows the sample...it sat for 24 hrs and I don't see phase separation so you may be right about the gas/oil comment I made (which was based on the liquid feeling slippery to me)

Why would the liquid be so dark? I note some residual solids at the tube bottom.

Other pic shows the transom area...I wet slip it so motor is tilted up.

Thanks for any additional thoughts

Tom IMG_8672.JPGIMG_8731 (1).JPG

[Harper]

For one thing, I never see the oil on my DF150 that dark, ever. Even times I went two years on an oil change. Particulates at the bottom likely crud from the tank. If you still have that sample, pour a little of it in a container of water and see what happens. If it's indeed oil (I still think not) it will float to the top and not mix. If it is the alcohol/water mix resulting from a phase separation, then it will mix with the water. What happens with phase separation is that the alcohol in the gasohol blends absorbs so much water that the alcohol AND water separate out of the gasoline, as a water/alcohol solution.

[catacom225]

Fresh gas is not necessarily good gas, you may have just bought a tank full of that crud, tip it out,clean the tank and fill it from another station

[Harper]

Catacom225 makes a good point. I'd be looking at ALL the gas presently in your tank.

[tsturm]

Remove fuel line at mechanical pump inlet, squeeze primer bulb, fuel clean? If clean change mechanical fuel pump. If fuel dirty drain tank & replace lines. What's your racor separator bowl look like?
let us know have a good one!

[tjo716]

Good morning and thanks again for the comments/suggestions.


Disconnecting line at low pressure pump and squeezing primer bulb shows that the fuel is clean. I don't have a separator bowl...just a standard fuel/water separator that I replace every year.

After 24 +hrs of sitting still, I see no phase separation occurring in the sample I took. Read through the tech manual again and for clarification, the sample came from the fuel vapor separator (which is directly under the high pressure fuel pump).

I have called many repair shops and they are all 5-6 weeks out on taking in new customers

[Murray]

You sample of fuel is not 6 weeks old, more likely 2 years old. When I purchased my boat it sat for 2 years, previous owner claimed the shop added fuel stabilizer to the tank which they did but did not run the engine or didn’t run it long enough to distribute the stabilizer throughout the entire fuel system. The fuel in the tank was the colour of an light American beer, the colour of the fuel from the VST was very similar to yours, the colour of a Guinness stout. Here in Canada most premium fuel is Ethanol free and that’s all I burn in my seasonal equipment/toys. I drained all the fuel in the entire system and replaced with fresh.

[tjo716]

Murray...thanks for your input. I may be missing something but when I pump the bulb (with post fuel filter line disconnected), the fuel that comes out is clear. So something happens bwt the low pressure fuel pump and the high pressure fuel pump that decolorizes it.

[Murray]

All I’m saying is you have old stale fuel in the VST. On my engine there is a small Phillips screw at the bottom with a small diameter clear plastic tube attached, open that and drain your VST collect the fuel in a glass jar and see if it’s clear. What could be happening is your adding a very small amount of new fresh fuel to old stale fuel and not getting the fresh fuel to the injectors. If the fuel is dark then you might want to consider draining the fuel rail. The service manual has a detailed method of relieving fuel pressure which I didn’t follow, I just opened the bottom bolt on my fuel rail with lots of rags stuffed in there and safety glasses on.

[tjo716]

Thanks for the response Murray ....understood.

I have drained the VST twice via the screw and plastic tube (that's where my dark sample came from) . Should I do this draining multiple times until clear? Or is the fuel rail draining (via the bottom bolt) the better way to do this?

Thanks

Tom

[Murray]

If you drained it once it should be sufficient at least in my case it was. I also syphoned the fuel from the tank and went all new fuel. If the dark fuel is still present after one draining then I would suggest you are sucking more bad fuel from the tank and filling the VST with bad fuel.