Small Projects:  Systems
This page was last updated on 26 March 2002.

Racor Filter Vacuum Gauge

This gauge is intended for use  to assist in determining when the fuel filters require replacement.  In the most basic terms, the gauge measures how hard the fuel pump has to suck to move fuel through the filters.  The higher the reading on the gauge, the harder the pump is working to pull fuel through.  When the gauge reaches a predetermined level of vacuum--the literature indicates 7-10" Hg--the filter elements require changing.   I thought this would make fuel system maintenance easier and more effective.  Rather than changing filters too often--wasting some of their filtration capacity--or, worse, leaving them too long before cleaning, this gauge should allow me to tell in an instant what the filters' condition is.

fuellinetee.JPG (175536 bytes)Installation was straightforward.  On the outlet side of my second primary fuel filter, I installed a tee in the fuel line to the engine.  Off the top of the tee, I attached a length of fuel hose that runs to the Racor vacuum gauge.  To keep it out of the way but also easily visible for inspection, I mounted the gauge between the two primary filters on the engine room bulkhead.  The gauge is intended to be installed in a panel somewhere, but, not having a suitable location--and not wanting vacuumgaugec.JPG (206999 bytes) the gauge exposed--I elected to just leave it mounted simply in the engine room.  I secured the hose in place with a couple plastic cable clamps, ensuring that the hose was out of the way and not chafing on anything.

Alternator Regulator On/Off Switch

Our large alternator charges the batteries fast.  It also uses a lot of engine power to run--a noticeable difference with and without.  Therefore, there are times when we really have no need to use the alternator for charging while motoring; why waste the engine power and reduce efficiency?

Because the system is set up with an external regulator, it is easy to incorporate a switch into the circuit.  The regulator is powered through the ignition circuit; turning the key switch on supplies power to the regulator, which then allows the alternator to charge the batteries.  If you  disconnect the regulator while the engine is running, the alternator stops charging.  Sure, the alternator keeps spinning, but is producing no power.   Therefore, all I needed to do was install a switch somewhere so that I could turn the regulator on and off at will.

I picked up a rocker switch from the store and installed it on my electrical board, above the LPG system controls.  Because it is difficult to cut holes out of this panel now that all the things are wired--plus, it's such a small hole--I used a 1/4" drill bit to drill all around the perimeter of the area I had marked out for the switch.  Then, I used a serrated utility knife to remove the rest of the material, and fine tuned it with a file until the switch fit.  The switch has a narrow flange that does not allow much margin for error, and also relies upon a friction fit, so I took it slowly to ensure that I didn't make the hole too large.  I was careful not to run into any of the existing wires behind the panel while I worked.

regwiring.JPG (172837 bytes)With the switch installed, I ran a doubled piece of #14 AWG red wire from behind the panel, along one of my existing wire chases, and into the engine room.  Once there, I connected one of the wires to the existing power supply (which runs from the ignition switch and, originally, directly to the regulator on/off spade); this wire now formed a continuous run up to behind the new switch.  The other wire, which will connect to the other side of the new switch, I ran up to the regulator on/off tab and connected it with a spade connector.

regswitchwiring.JPG (186191 bytes)Then I made up the connections behind the new switch.  Without paying attention to which wire was which, I connected them to the two screws on the back of the switch with ring terminals.   Later, when I run the engine again, I'll determine which switch position is on and which is off, and install an indicator as necessary.

Glissando, Pearson  Triton #381

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