Diesel day tank WAS: Fuel Tank Solenoid Valve

[RichCarter]

I’ve had plans to install a day tank for my fuel system for years but have not found one.  Dickson makes one for their cabin heaters but I don’t think it has the level switches.

 

A day tank is a small second tank that sits between the main tank and the engine.  It is normally mounted up high where it gravity feeds the engine.  You only need a couple of gallons. It has an inlet, outlet and return line much like the main tank but also has a low level alarm that is set for something like half full.  An electric low-pressure pump fills the day tank from the main tank.  When the key is on, the tank fills.  If the level gets below half, an alarm goes off.  The fuel return from the engine goes to both tanks.  Overflow from the day tank goes through the return line back to the main tank.

 

For a two-tank system you need both a return line and vent line for the day tank.  You connect the vent line from the day tank to the vent line of the main tank instead of the fuel return and add a second level switch that turns the pump on when the level reaches something like ¾ empty.  A tank selector valve selects which tank to draw from.  The return line on the main tank is unused.  A tank selector valve selects which tank to draw from.  Since the return on the main tank is unused, you need not need a valve on the return line from the engine to select which tank to feed.

 

The day tank has a few advantages. 

1 – You can draw from the main tank until it runs dry.  When the alarm goes off you know you still have an hour or more running time before the engine sucks air. 

2 – You can put a filter between the day tank and main tank.  If it clogs, the engine keeps running and the alarm goes off. 

3 – It simplifies the addition of multiple tanks.

4 – If the low-pressure pump fails, your engine keeps running and you may never really know anything happened.

 

It has one disadvantage.  If you lose electric power, the engine will run the day tank dry without setting off the alarm.

 

If anyone finds one or knows where they can be fabricated at a reasonable cost, please let me know.

 

Rich

 

[Author]

Posts