Breaking fuel line for Floscan sender

[scottinsydney]

Some of you may know that Floscan has gone out of business in the last few weeks.

A couple of months ago I sent my two gauges to be converted to litres per hour, buy an especially adapted NMEA2000 Flonet system and also to purchase a Starbard side delivery and return sensors. These appear to have been shipped to me in Australia on the same day that Floscan folded. Unfortunately there are no complete instructions for the specially adapted wiring of the 36 individual wires used to connect gauges and Flonet unit.

I have put out an all points bulletin to find the helpful Floscan technician Who worked on my project.

Regardless, I have pressed on and now have the forward and return sensors installed. The old Floscan sensors were bypassed by a previous owner as they leaked. I will now have to break the fuel line hose at a joiner between the Racor filter and the 12V71 fuel pump to connect the delivery sensor. This part is straightforward. I’ll also close the fuel cock so the fuel does not run back into the tank.

The motor does not have a priming pump. When I break the fuel delivery hose at its join and connect the sensor, air will get into the fuel line, and the motor might be starved of fuel after it starts.

What would be the best way to ensure that after the motor has started that it will continue to run while air is purged? Does the engine’s fuel pump have enough suction to draw fuel alongside and up over 5’ of fuel line? Previous owners must have primed the engine’s fuel lines somehow in the past. On my previous 8v92s it was easy to get to the engine’s fuel pump fitting and prime the fuel line. Not so on the 12 V 71.

floscan1.jpg

Spaghetti junction... this is the old floscan wiring under flybridge dash.

floscan2.jpg

New delivery sensor installed ready for hoses to be connected. The fuel line to the left of the sensor going to motors fuel pump will need to be primed somehow?

[BOATER BOB]

While you have everything apart install an electric fuel pump to prime dosent have to be a big one if teed in and valved off and can be used to prime both engines.
Bob

[piripucha]

You can also put a priming bulb like they use on outboard engines. The ideal set up would be in parallell with a pair of valves, although you can also put it in line after the flowscan senders. I have this set up in one of my generator, but I must admit that the fuel lines are smaller in diameter. . Actually with the humungus size of outboards I bet there are priming bulbs of the neccesary size.I hope this helps

[racclarkson@gmail.com]

Scott, I still prefer the cross-feed approach of running a fuel line and ball valve between the motors. One motor can prime the other; there's no pump or wiring to deal with, and you can run two engines off one's fuel supply if it comes down to it.

IMG_6976.jpg

[MVCaprice]

Uggh. That is bad news. I am super glad that I just bought all new dampeners from them last year. It did seem a bit odd that Fisheries no longer was carrying their replacement parts however. I suspect they had some sort of a A/R issue.

[MVCaprice]

You really need a lift pump. I will never go back to those pre-pump days. I can dump the entire fuel system and i don't even have to bleed to get it started again, just 45 seconds of priming.

Do you have a "prime" valve on your fuel manifold? I'd love to see what your manifold looks like. Can you share a pic? I have been trying to understand whether ours is original or not.

[Pascal]

Where do you tap the Xfeed, before the racors? I don't see the benefits for priming. Even if the xfeed is after the racors you re going to pulll air thru to the running motor.

I thought all Hatts were plumbed to pull fuel from either tank

I was going to put priming pumps on my new fuel Yates but the mechanic talked me out of it saying the Cummins don't loose prime. Had so many thing to worry about I followed the advice but eventually I will add them. Worth the convenience when something goes wrong.

[racclarkson@gmail.com]

I tap it out at the secondary (vertical line pictured) and back in at the secondary; e.g., secondary to valve to secondary.

IMG_6975.jpg

Say I've worked on the port motor and need to prime. I start the starboard and open the cross feed valve. Now I'm sending fully filtered fuel to the port motor. When I see the fuel pressure gauge on the port motor registering, more or less, the idling pressure of the running motor, I know I'm ready to start the port motor. Being Detroits, they are not much bothered with what little air is then passed being pushed along by lots of fuel.

Example: When I change secondaries, I don't mess with filling the cannister. I just lube the O-ring, screw it on, crank the other side and open the ball valve. When I see pressure building, it's time to start. Then I can gradually close the valve which increases the suction in the port side lines. If the port motor stumbles, you just open the cross feed valve a bit. The whole process is over in under a minute, and there's nothing to wear out.

You may or may not have do a proper bleed with your new motors, but at least with this system you've got plenty of clean fuel helping out. And as I mentioned earlier, I can tell you the cross feed will run two Detroits at cruise off one supply.

As for Hatts pulling from either, correct. And that's fine unless you get trash in the manifold valve. I ran a tank dry on a run to Florida in '16, and the cross feed kept me underway for almost two days. If you loose a fuel pump, cross feeding will let you run two on one.

[scottinsydney]

Here is my short term solution.... the new priming hose barb is 5/16" and a mini fuel valve is installed.

I could use either a 12 volt fuel pump or an outboard motor fuel bulb to prime line from Floscan sensor to engine fuel pump. The bulb will be easier to rig up than rigging up a 12 volt pump.

Question: With engine off will fuel pump allow air to pass through it when I squeeze the bulb?

If not I'll use the electric pump and turn it on before I start engine.

I will install Robert's priming solution next time I change secondary fuel filters.

flowscan3.jpg

[racclarkson@gmail.com]

Here is my short term solution.... the new priming hose barb is 5/16" and a mini fuel valve is installed.

I could use either a 12 volt fuel pump or an outboard motor fuel bulb to prime line from Floscan sensor to engine fuel pump. The bulb will be easier to rig up than rigging up a 12 volt pump.

Question: With engine off will fuel pump allow air to pass through it when I squeeze the bulb?

If not I'll use the electric pump and turn it on before I start engine.

I will install Robert's priming solution next time I change secondary fuel filters.

Attachment 25887

Not enough to matter. Get the lines fueled from the racors to the pump and it'll be ok. Motor may stumble or quit a time or two. Once it fires it'll push fuel in a hurry.