A new fuel system for Jedi (English)

Jedi is a sailboat and we only use the engine for getting in, around and out of harbour so it gets very little use. When we do use it however, it is crucial that it runs 100% as we often manouver in between reefs where an engineproblem might wreck the boat. Also, we tend to run the generator a lot (we're spoiled) and we have 400 gallons of diesel fuel aboard which lasts about a year. The fuel we can get tends to have dirt, rust, water and bacteria in it. Also, it seperates quickly so that the heavier components end up on the bottom of tank, forming a sludge when left there for long.

After reading a lot on the Internet we came up with the system in the diagram below. Please note that we didn't invent this; it's a combination of many designs as encountered on the net. Click the diagram and photo's for a bigger version.

Everything except the fueltanks, engine and generator was replaced with new parts. The filters are all Racor 500 series; the pumps are Walbro 6802; the manifolds and valves are manufactured using 1/4" bronze and brass parts and the fuel-lines are 3/8" flexible hose type A1. Instead of hoseclamps, we used monel wire and the Clamptight tool. Threaded connections on the bronze and brass parts are sealed with Permatex "High Temperature Thread Sealant".

The transfer manifold (first photo) is located beneath the connection to the tanksumps, so it is always flooded by gravity. It has 4 valves. Two connect to the tanksumps. The third connection is via a Racor filter to the electric fuelpumps (2nd photo). One pump is labelled "transfer/polish" and it is connected to the return manifold. This pump has a mechanical timer switch. The other pump is labelled "boost/prime" and connected to the supply manifold. It has a regular on/off switch which can be seen on the first photo... just hanging by it's leads as the switches aren't mounted yet. These pumps have a maximum rate of 43 gallons per hour and limit the pressure to 7 psi. The fourth connection is dual purpose (a small piece of transparant hose is connected to it on the photo) . It can be used for draining the worst from the sumps or it can be used to pump fuel from a drum or jerrycan when valves to both tanks are closed. For normal operation all valves are closed.

The supply / feed manifold (third photo) is located under the filters and has 7 valves. Two connect to the draw-pipes on the fueltanks. The 3rd is for the engine pre-filter; no. 4 is for the generator pre-filter; 5 is for the diesel-heater; 6 is the boost/prime pump and the 7th is a spare. For normal operation the valves to engine, generator, heater and one tank are open with the rest closed.

The return manifold (fourth photo) is located above the filters. This is where the return lines from generator and engine are connected, plus the return lines back to both tanks. The other 3 valves are for the transfer/polish pump, a spare again and a tap for clean fuel. For normal operation, valves from generator and engine are open, plus one valve for the return line to the tank (same tank as we draw fuel from).

The fifth photo shows the Racor 500 filters. The filter for the engine is a dual-filter with cross-over manifold and vacuum-meter to check the state of the filter elements. Water and dirt settles in the transparant bowls and can be drained with the valves we fitted there instead of the standard plugs which are messy.

Now we come to the list of procedures which cover every maintenance operation using the system.

• Equalizing tanks. As we always draw fuel from the starboard tank (closest to filters), we end up heeling to port as the tanklevel goes down. If not underway, we can equalize the levels by opening the two tank-sump valves on the transfer manifold. While underway we need to equalize by doing a fuel transfer instead.
• Fuel transfer. On the return manifold, open valve to the tank with the lowest level and check that the valve to the other tank is closed. If generator and/or engine are running, switch their feed to the fullest tank, using the engine-mounted pump(s) for the transfer. If they aren't running or to speed up the process, do the following: on the transfer manifold, open valve from fullest tank and valve to the filter/pump. Switch on the transfer pump choosing an estimated time for transfer on it's timer-switch and open the pump-valve on the return manifold.
• Bunker fuel. Before bunkering, perform some polishing on each tank to make sure the sumps are clean. If one tank is empty, add some fuel to flood the sump before polishing. Add biocide to both tanks before starting to take on fuel. We normally need 350 or so gallons of diesel (1300 liters) and it takes too long to filter with a Baja filter while bunkering, so we have to take it as it comes from the hose. After bunkering, we wait a couple of hours so that water and dirt settles on the bottom of the tanks (hopefully most of it ends up in the sumps). After that, follow both the drain sumps and polish fuel procedures.
• Drain sumps. Drain each sump seperately by opening it's valve on the transfer manifold. Hold a glass jar under the spout of the drain valve on the transfer manifold and crank the valve to fill the jar halfway. check for dirt and/or water and keep draining until no water and mostly clean fuel comes out. This is normally less than a jar.
• Polish fuel. Polishing is basically the same as transferring. The goal of polishing is to filter all fuel and recirculate it so that the components are being mixed again. If there's less than one full tank left, transfer all fuel to one tank and next all fuel to the other tank. Check tanklevels regularly for known flowrate. Change filter-element when flowrate gets too low.
  When there's more than a full tank you have the option to circulate within the same tank. Do not transfer from one tank to the other in this case as you're putting all the heavier components in one tank, changing the fuel specification. Rule of thumb is that to filter all fuel, circulate 6 times the volume of fuel in that tank. Complete the procedure by equalizing tanks.
  The transfer/polish filter normally holds a 10 micron element. If this clogs up too fast, replace it with a 30 micron element and do a second polishing cycle with a 10 micron element. The 30 micron elements can be washed with diesel if it's really bad.
• Tap clean diesel. This is done using the "tap valve" on the return manifold. Run either the engine, generator or transfer-pump to pressurize the return-manifold so you can tap the fuel. Close connection from return manifold to tank for more flow but don't forget to open it again when done!
• Change racor filter element for generator. First, close the generator valves on both supply- and return-manifolds. Put jar under filter-drain and open drainvalve until flow stops; close this drainvalve again. Open the filterhousing by removing the big T-bolt on top. Remove the lid. Remove seals on both T-bolt and lid and dispose. Clean bolt and lid and fit new seals which come with the new element. Now drain the filter again until housing is empty. Take filter element out of housing using the integrated handles (you might need to pry them up). Rinse the housing with clean fuel using piece of hose and the "tap clean diesel" procedure. Drain again and clean housing in & out with cloth and insert new element. Now fill until element is fully submerged (tap clean fuel procedure). Put lid and bolt back. Open the generator valves on supply- and return-manifolds. Start the generator and check all valves for normal operational position.
• Change racor filter element for engine. The engine has a dual filter which results in the quick solution by just switching the valve on the filter itself to the other element. When the engine is running, make sure to first turn the valve to "both on" and on to the other element instead of first to the "both off" position in which case you interrupt fuel flow to the engine. You can change the dirty element later if you're busy like steering through reefs. Always change the element that is not in use, regardless if the engine is running or not. Follow the same procedure as for the generator but don't touch the engine valves on supply- and return-manifolds as the cross-over manifold of the dual-filter already isolates the not-in-use filter for replacing. This way, the engine can run while changing the element. After replacing the element, test it by changing back to it for a couple of minutes. Change back to the other element again so that you alternate element-changes between left and right filter-housings. When done, check all valves for normal operational position.
• Change racor filter element for transfer/polish. Don't let this element get too bad as it's also used for the boost/prime pump which might get used in emergency situations. Replace the element when you notice a reduction of flow during transfer/polish operation.
  The input for the filter comes from the transfer manifold and the valve should already be closed for normal operation. Same is true for the valves connecting the pumps to the supply- and return-manifolds. Follow the same procedure as for the generator filter. Note that you can't use the electric pump for tapping clean fuel so you will have to run generator or engine or tap the fuel into the jar before opening the filter housing.
• Boost. Shit happens and you might end up with a clogged primary and/or secondary filter at the wrong moment. If it's the engine's primary racor filter you can quickly change over to the other element but you would need to replace filters when it's a secondary engine-mounted filter or one of the generator filters. With this procedure you win some time by changing from vacuum-feed to pressure-feed. First, on the transfer manifold, open the valve to the tank that's also selected on the supply and return manifolds. Next, turn on the boost/prime pump and open the valves connecting the boost/prime pump to the transfer- and supplymanifolds. Last step: close the tank-valves on the supply manifold. The fuel supply to the supply-manifold is now handled by the electric pump which keeps the manifold at 7 psi. The connected Racor filters can handle 15 psi pressure although Racor does not recommend positive pressure for normal operation (but this isn't normal operation). Because of this help from the pump, the engine or generator will get enough fuel again.
  This procedure also solves another, related, problem: air getting into the fuel-lines, starving or stalling the engine. This is related because it mostly only happens with dirty filter elements which cause more vacuum and might trigger a leak that way. Always test the T-Bolt on top of the filter for tightness as this is the most likely point where air gets into the system.
  The third problem that gets solved with this problem is a failing lift pump on the engine or generator. The Walbro boost/prime pump takes it's job over giving you time to replace the liftpump later. Note that a lot of failures on lift-pumps are due to a leak in the membrane of the lift-pump. With the boostpump running, fuel will get into the lube-oil of the engine which will lead to disaster. If the lube-oil level is rising, stop using the engine until the lift-pump is repaired. In an emergency situation, the engine is running so you can't check the oil level and this might get you past the reefs ...
• Prime/bleed fuel system. This is the same as the "boost clogged filter" procedure. When the pump is running but the engine/generator is not, the whole fuel system gets pressurized to 7 psi. You can even start bleeding remaining air from the Racor pre-filter, followed by all the bleed-points on the engine without touching any manual levers on filters or lift-pumps. When bleeding is done, leave the pump on and open the tank-valve on the supply manifold again. Fuel will start flowing in reverse: from manifold to the tank, priming this line too. Next start the engine or generator with the pump still running and close the valve from pump to supply-manifold after a minute or so. Fuel flow will reverse again from tank to supply-manifold for normal operation.
  You can also use this option to fill the filterhousings when changing filter elements instead of the "tap clean fuel" procedure.
• Pump dirty fuel from rusty cans. This procedure is untested at this time but will surely work. Make sure you have a length of hose long enough to connect to the drain-valve on the transfer manifold on one end and running over the side of the boat to the floor of a dinghy alongside. Put it in a can /drum of fuel, start the transfer pump, open the valves on the transfer manifold connecting the pump to the hose (keep tank connections closed), open valves on the return manifold connecting the pump to the tank of choice and transfer fuel from the can to the tank while filtering!
  The transfer manifold is below waterline so after initial prime is achieved, the pump is only helping with a little lift and resistance of the filter. If the flow-rate isn't enough, you can add the boost/prime pump (reverse flow from supply manifold to tank) but total flow should not exceed 60 gallons per hour which is the maximum rate for the filter. If there is a problem with the initial prime, fill the hose with fuel before handing over the side (use "drain sump" procedure).

The new fuel system is so flexible that we still discover more functionality as we use it. Although there are many valves, choosing which ones should be open or closed is easy with the task in mind. It's our opinion that this is the ultimate system except for a gravity-feed / daytank solution which isn't possible on many boats. Please react to this article if you find errors, other uses or better ways for operating it.

Ciao!
Nick.

Comments

[Geplaatst door: Yvonne en Maarten]

Hi Nick,
Another very thorough article and particularly interesting!
What do you think about those vacuum gauges from Racor? They are sold separately and fit on the T-handle of the filter house. The analogue display tells you when the filter gets clogged. No more unnecessary filter replacements and instant diagnose. Budget Marine sells them.
It works nicely on our installation.
Hasta luego,
Yvonne and Maarten, o/b Sea of Time
Still on the Rio Dulce, Guatemala

[Geplaatst door: Nick]

Hi Maarten,

The dual Racor filter has a vacuum gauge which is located between the two housings (you can see it on the 4th photo). I don't need gauges for the genset and polishing filters as we only replace those when fuel flow stops ;-)

Note that I heard unhappy stories about the T-bolt replacement gauges. Racor also sells a seperate gauge to be installed in the fuel line between filter and engine and this is the preferred solution according to the people I listened to. We have one... somewhere on the boat... when we find it, I will propbably install it between polishing filter and electric pumps.

ciao!
Nick.