diesel fuel aeration resulting in dead engine

[i-Zapp]

Twice now with my 33' Hunter sailboat have I "run out of fuel" due to sloshing of the diesel in the tank. In both cases, I've had 1/4-1/2 tank of fuel, and of course really needed the engine in heavy weather. The remedy was to simply bleed the fuel system (the next day).

Short of always traveling with a full tank, the other solutions seem to be some sort of anti-slosh in the tank (foam?), or some system to actively "filter" the air out of the fuel.

Am I the only one experiencing this? Is there a simple solution?

[skipperpete]

Originally Posted by i-Zapp

Twice now with my 33' Hunter sailboat have I "run out of fuel" due to sloshing of the diesel in the tank. In both cases, I've had 1/4-1/2 tank of fuel, and of course really needed the engine in heavy weather. The remedy was to simply bleed the fuel system (the next day).



Short of always traveling with a full tank, the other solutions seem to be some sort of anti-slosh in the tank (foam?), or some system to actively "filter" the air out of the fuel.



Am I the only one experiencing this? Is there a simple solution?

A day tank is a good option for many reasons other than to stop getting airlocks but a bit difficult to accommodate on a 33footer.

[GILow]

Originally Posted by i-Zapp

Twice now with my 33' Hunter sailboat have I "run out of fuel" due to sloshing of the diesel in the tank. In both cases, I've had 1/4-1/2 tank of fuel, and of course really needed the engine in heavy weather. The remedy was to simply bleed the fuel system (the next day).

Short of always traveling with a full tank, the other solutions seem to be some sort of anti-slosh in the tank (foam?), or some system to actively "filter" the air out of the fuel.

Am I the only one experiencing this? Is there a simple solution?

It does sound a little odd. Is there a chance the pickup in the tank is not correctly placed? Either not on the centerline of the tank or perhaps not low enough?

[hpeer]

Do you have an access port?
I presume you have baffles, are they in place?
The baffles are the “anti-slosh” you are seeking.
How big is the tank?
Is it shallow or deep? Rough dimensions.

[EngineerRetired]

One possibility... https://fassride.com/what-is-fass/

[C420sailor]

No disrespect intended, but are you sure it’s foaming/air that is causing it? And not dirt and debris getting kicked/sucked up when the fuel drops to sloshing levels?

[chrisr]

my first thought is what baffles are fitted in the tank ?

these are ? should be ? there to stop exactly the situation you describe...

cheers,

[wsmurdoch]

While I have never had my engine quit due to aeriated fuel, I have worried about sucking air into the fuel system when the tank level is low and the boat is violently pitching. We came out of a cut in the Berry Islands of the Bahamas several years ago in a wind over current situation where the waves and opposing current were worse than I expected when I entered the cut. At near full throttle we were making little headway, the bow was alternating between the sky and underwater, and I was afraid to turn around in the narrow cut. We got out, but had the engine quit, we would have been in serious trouble.

Parker Hannifin describes the use of a tee after the fuel pump to remove air from the fuel stream to the engine in the first column of the second page of this pdf. https://www.parker.com/literature/Ra...iesel_Fuel.pdf
The fuel under pressure enters a tee from the side, air escapes through a flow limiting orifice at the top of the tee to the diesel fuel return line then back to the fuel tank, and air-free fuel leaves from the bottom of the tee and continues on to the engine. It is sort of a really small day tank. I have thought about making one, but I have not.

(I assume Parker Hannifin is envisioning a fuel system: tank - primary fuel filter - electric fuel pump - "the tee" - engine mounted fuel pump - engine mounted fuel filter - injection pump - injectors. I also assume the tee is large, not 1/4" like my fuel lines, but maybe 2" or so to give time for the air to disengage.)

[pdxsailordiver]

I had a very similar problem with my fuel system. 2 tanks same problem both tanks. Finally removed both tanks ( yes it sucked) tank builder didn’t put in return tubes at all. I installed tubes to bottom of tank. They work great now.

[hlev00]

These, or something similar, looked interesting and I was considering them for my forward water tank under the v-berth. I passed on them because I was afraid that they might dislodge the pickup. You'd also need a tank sender that does not rely on a float on an arm.


https://www.qspray.com/surgebuster-tank-baffle-15/

[Bill O]

Originally Posted by i-Zapp

Twice now with my 33' Hunter sailboat have I "run out of fuel" due to sloshing of the diesel in the tank. In both cases, I've had 1/4-1/2 tank of fuel, and of course really needed the engine in heavy weather. The remedy was to simply bleed the fuel system (the next day).

Short of always traveling with a full tank, the other solutions seem to be some sort of anti-slosh in the tank (foam?), or some system to actively "filter" the air out of the fuel.

Am I the only one experiencing this? Is there a simple solution?

I think we do not have all the info needed determine what is going on.

When was the last time you cleaned the tank?

What primary filter do you have and when was the last time you changed both the primary and secondary filters?

Do you have a vacuum gauge on your primary, if so was it a high or low vacuum when it shut down?

When you bleed your system is it with an electric fuel pump on an "easy bleed" motor?

What motor do you have?

From what info that was presented so far, I'm leaning towards a high vac. (clogged filters) causing depleted fuel in the primary or a leak in the primary seals/the fuel line going to the tank (also depleting the primary of fuel).

[sailingchiro]

Wondering if you are sucking in air from valve, filter, seal, hose, etc.

+1 on emergency day tank with enough extra fuel hose to get to day tank. Just have to run return hose and suction hose to day tank.

On long passages, we always keep two jerry cans for emergency.

[Anchorage Frank]

I'd replace the Racor (assuming you have one); they seem prone to allowing air into the fuel system.

[Louis Simon]

Plastic fuel tanks do NOT have baffels. Motoring into bumpy seas causes the pickup tube to suck air. Mine did even with a half full 26 gal tank. Some type of day tank you could switch to under these conditions could keep you going. No problem during flat seas. I have a large locker behind the engine room where I installed a "saddle tank" from a power boat ~3ft long <6inches wide and ~2ft deep,19gal. By the way-when hobby-horsing in rough seas I turn off my bilge pump as I discovered it was on/off due to sloshing bilge water. Same thing on a previous boat. Every couple hrs I would check the bilge or crank the manual bilge pump to ensure bilge was OK.

[Enfant Du Vent]

Ahoy i_Zapp:
I'm with those who suggest you check for sludge in tank that could be causing you to suck air from a clogged filter, hose connection, etc., etc.
The one time I had a problem with engine not running--except in idle--even though there tank was almost full was after an 8 day offshore passage. (totally under sail)
When I studied the shop manual, not just the owner's manual, I discovered there was one more screen filter in the fuel system....that I had been unaware of. From then on checked all screens whenever bleeding system and never had that problem again.