DF70 Fuel Leak/Spilling

[Bdoherty9]

Was out for a run on the boat yesterday, did out 50 miles then the engine stalled out. Tried to start it back up and fuel was coming out of the silencer Cover in the front of the outboard. I was able to get to the ramp and get it home. While flushing the engine found another leak on the starboard side of the engine that was also coming from a hose just off of the silencer cover, this Hose was just pouring out fuel. My guess is maybe a fuel pump issue, does anyone have any ideas? Thanks!

[Bdoherty9]

Was out for a run on the boat yesterday, did out 50 miles then the engine stalled out. Tried to start it back up and fuel was coming out of the silencer Cover in the front of the outboard. I was able to get to the ramp and get it home. While flushing the engine found another leak on the starboard side of the engine that was also coming from a hose just off of the silencer cover, this Hose was just pouring out fuel. My guess is maybe a fuel pump issue, does anyone have any ideas? Thanks!

Looks like it's the "evaporation hose" where it routes down the starboard side of the block.

[Bdoherty9]

Here's a picture of fuel spilling out

[Harper]

Welcome aboard, Bdoherty9,

Sorry to hear that you're having this problem (that's a LOT of fuel coming out of there!!) but hope we can help. I am not that familiar with the DF70 per se, but it seems to me that the fuel must be coming from the VST, the vapor separator tank. The low pressure fuel pump feeds fuel to the VST, and the inlet to the VST is via a float valve (like the fuel bowl of a carburetor). If the float sticks or a small foreign body causes the needle valve not to close, then the tank can overfill and overflow out the vent tube. On the larger outboards, the vent tube vents fuel vapors to the crankcase, and if this happens to us, we end up "making oil" or diluting the oil in our crankcase with raw fuel (not a good thing). Someone familiar with the DF70 will have to confirm that the vent tube from the DF70 vents to the air to validate my theory. But for now, that's my only suggestion. If it is a stuck float valve, then you'll have to open up the VST to discern the reason for the overflow out the vent tube.

[Bdoherty9]

Mike,

Thank you very much for the response. What you said makes sense. I do believe it is the vent tube and it would make sense that the float is stuck. While the outboard is running if I disconnect the fuel line going into the outboard it stops spilling out of the vent tube. Which makes sense because then it will use up the fuel in the bowl instead of asking for more from the tank. Are there any other concerns I should take when pulling apart the VST? Could there also be a problem with the fuel pressure regulator?

Good to know that much fuel is not headed to my crankcase and I caught t before it dumped too much into the water!

[Harper]

There is no reason to suspect that there is any problem with the fuel pressure regulator. Its function is to maintain the proper pressure (relatively high) in the fuel rail for the injectors. The high pressure fuel pump is inside the VST, immersed in fuel in the reservoir, and the pressure regulator is also there and very nearly integral to the pump unit. Any fuel that has to be bled off to maintain the proper pressure in the rail is dumped right there into the VST reservoir, so the actual level of fuel is still solely dependent on a properly functioning float to control the fuel flow as it comes into the VST. The only thing to be concerned about in taking apart the VST is gaskets and seals. If you're careful you should be able to take the chance that they are reusable.

[Bdoherty9]

Thanks for your help. Got the manifold off tonight and pulled apart the VST, to find the guts have been haggard by ethanol fuel and water. Looks like it's in pretty poor shape. The high pressure fuel pump was working just fine but based off the shape of the housing do you think it should be replaced? I've dismantled the whole assembly and I'm soaking the parts in sea foam for the night.

[Bdoherty9]

You can see all of the sediment already falling off after just a few hours.

[Harper]

Well, personally, I would not spend the money on a pump that was running okay, because those high pressure pumps are not cheap. Assuming that it cleans well, and checks out operationally, I'd save my money and run it 'til it quits. Replacement will be easy when the time comes, now that you've got experience in getting to it.

[Solarman]

Bd9, you may want to examine your fuel tank, possibly empty and clean, replace/ or clean all filters, clean out, and check all lines for ethanol damage before starting back up. It wouldn't help to clean all these parts then send same contaminated fuel right back in? Also, would help to keep sea foam in the new/good fuel.

Just some thoughts.
Good luck.

[Bdoherty9]

All cleaned up and she's up and running again. Cleaned the lines and tank and inspected them for ethanol damage. Replaced the fuel water separator, HP, and LP filters and filled her up with ethanol free fuel. Now the weather needs to cooperate so I can get a day out on the water.

Should have known when you buy a 10 year old boat with empty tank and it only has just over 50 hours, that it would be gummed up for sure!

Thanks again for y'alls help!

[Harper]

Thanks ... appreciate the update, and glad to hear you got 'er running. Happy boating!