Fuel system issue.

[CK 17]

Hi all,

I thought I had a thread about this from last fall, but I can’t find it so here’s a new one with an update.

I have an 1984 Oday 26 with a 1GM. Last fall, after putting the boat on the hard, I pumped out the fuel tank as best I could. I removed about 13 gallons of some really ugly looking diesel. I replaced it with 10 gallons of new. I didn’t add any fuel treatment because I figured the new fuel would have enough to get me through the winter and I’d add some this next fall.

in short, I thought if I removed to old fuel and added new fuel I’d do no harm.

so….this spring I hook up water, bleed the fuel system and run the engine for 15 minutes. It runs fine.

the next day I put the boat in the water and run the engine another 15 minutes. It runs fine.

a couple of days later, in order to put up the furling jib on a super windy day we reposition the boat to a slip into wind and it runs fine.

the day before yesterday we go sailing and use the motor about 15 minutes with no issues. After a great sail I fire up the motor, take down the main, furl the jib and motor in. Entering the marina the motor stops. It didn’t it show any unusual symptoms, it simply stopped as if I pulled the fuel knob.

I yank out jib and sail through the marina to the slip. Other than some yelling at a pontoon boat it went without incident.

the next day I pull and change both filters which look clean.

in the process, I find the tank filter housing full of fuel. The filter housing on the engine is empty. Obviously, some air got into the system somehow but everything seems tight. I bleed the air out of the system and start the engine. I run it for 30 minutes, in gear and it runs perfect. Today I went back to the boat and inspected the fuel vent and ran the engine in gear at 1500rpms for another 30 minutes with no issues. I found no leaks.

any thoughts on why it might have failed at just about the worse possible moment?

[coelcanth]

sometimes there is a mesh strainer on the pickup itself inside the tank. it is often the first place for the algae that grows in the diesel to get stuck and cause a problem.
unfortunately it's also the hardest spot to access and clean, but it might be worth a look. since the filters look clean, that would be where i might start

[CK 17]

Thanks. I have considered this but The top of the tank goes up to within 2 inches of the underside of the footwell. I’m not sure I could maneuver a 14 inch pickup out of there. I guess I might have to pull the tank. I know it’s possible because I found an old receipt for when it was done 35 years ago.

[Ron Williamson]

If the tank filter is full and the engine filter is empty, it points to an air leak/ bubble between the two.

A tiny diesel, under no load, will take forever to use a filter full of fuel,so I would guess that there was a bubble of air between the filters due to incomplete bleeding.

In my experience,given the chance, a boat will make you look foolish.
R

[Breakaway]

Thanks. I have considered this but The top of the tank goes up to within 2 inches of the underside of the footwell. I’m not sure I could maneuver a 14 inch pickup out of there. I guess I might have to pull the tank. I know it’s possible because I found an old receipt for when it was done 35 years ago.

You could also consider what, in fiberglass boatbuilding , is sometimes referred to as a soft patch.

You cut out out the bottom of your footwell nice and square, leaving enough room around the perimeter so you can install a lip or flange. Service the tank. Then, you put the cutout section back with screws and sealant. The soft patch is watertight, and meant to only be opened rarely. One is often located above tanks due to situations precisely like the one you now find yourself in.

Kevin

[CK 17]

Thanks Kevin. That’s well within my abilities and I had not thought of that. It sounds a lot like kayak hatch openings I’ve made.

[Canoeyawl]

Any filter or connections on the suction side of the transfer pump are susceptible to an air leak. The more parts associated with a filter in that location the more suspicious (Raycor) If you must have a filter on the suction side, use a one piece spin on filter, or a simple inline filter for diesel (perhaps a Wix 33007) I don't like Raycor or similar composite filters in that application, especially on a boat.

(At my local harbor there is a bar to cross and precisely when you need full fuel flow is when you may effect an air leak (at an o-ring seal) if the filter is on the suction circuit. We have seen more than one boat on the bar for this very reason)
If the engine is running and moving the boat will always use more fuel than at "idle" (idle being "not working" and not a particular rpm)

Your saying the filter at the tank (suction) is full, and the filter at the engine (pressurized from transfer pump) is empty would seem to indicate the issue is between the tank and the second filter or transfer pump. I suspect that a simple count of the mechanical connections (possible air leaks) on the suction side will reveal a number of potential suction leaks (include any joints in the filter assy in this count)

If it was mine, or if I was hired to solve this riddle I would bypass the filter on the suction side with a length of clear hose (to see any bubbles in the event of a leak at the internal fuel pick-up) and use only the filter provided by Yanmar as a preliminary test. (This factory filter will be between the transfer pump and the high pressure pump i.e. pressurized) You will have to load the engine to test, perhaps by running it at the dock in gear at full throttle for an amount of time that will effectively rule out failure.

[John B]

Its probably as identified as above ,but one must never forget the stop cable /solenoid gremlin. Worth a check there's nothing stopping it from seating back to run position , some off season corrosion or , or.
and tank vent. blow that through to check for insect nest etc.

[Canoeyawl]

Or it could be a blockage at the pick-up, causing an air leak (somewhere) on the suction side.
And a blockage often has the ability to fall away from the pick-up tube when the engine has stopped. Lying in wait for the next demand from the governor for fuel...

[Andrew Craig-Bennett]

If the tank filter is full and the engine filter is empty, it points to an air leak/ bubble between the two.

A tiny diesel, under no load, will take forever to use a filter full of fuel,so I would guess that there was a bubble of air between the filters due to incomplete bleeding.

In my experience,given the chance, a boat will make you look foolish.
R

How true!

I have been driven to distraction by Kukri’s fuel system.

It ought to be almost perfect - two big stainless tanks and a ten year old Yanmar.

However - we put the boat afloat and pottered happily round the Solent. We set out to bring her to her new home port and the engine promptly died after two miles with two hundred to go.

Diesel bug. So I had the system comprehensively de-bugged. End of Round One

Round Two was a tiny entrained air leak from the place where the generator and the Eberspacher drew from. This took for ever to solve.

I may be lucky this time but if not I shall be following the example of a former employer who had a large passenger cargo ship which went aground with engine failure - they consulted the most expensive feng shui ​man in Hong Kong.

[Canoeyawl]

Feng shui Diesel?
I know that guy, he can be found in a place of prominence at any yacht club bar.

[Andrew Craig-Bennett]

My current plan is to replace the line from the tanks to the engine fitting a pair of Racors in the process.

[Paul Schweiss]

The Yanmar lift pump is a simple rubber membrane that could have failed, thereby not forcing fuel towards the secondary fuel filter and injection pump. The primary may be getting filled by gravity depending on the set up and how full the tank is.
if your primary filter was empty I might be suspicious of a clogged vent line/fitting, or fuel pick up, or algae growing in the tank clogging things.
You could day tank the engine by picking up fuel from a separate container- 1 gallon will run you a fair bit. If it ran under load for some time then the problem is between the fuel tank and the engine. And a 1 GM does not have a return line.

[hawkeye54]

Just an opinion - you say above 'after a great sail' . . . If the boat was moving through chop or waves, you may have stirred up whatever was on the bottom of the tank, and blocked the pickup tube.



Rick