MonCal.doc  1/30/03

 

1. BACKGROUND

--The Empty adjustment on the Centroid sender is to adjust for the length of the sender.  It is normally set with no fuel on the sender.  Typically this adjustment will have been set by Centroid and sealed with brown Permatex.  That's because Monaco orders senders of specific lengths for specific tanks, and we set the Empty to match that length.  If you shorten a sender to put it in a smaller tank, which we prefer you didnt, the Empty adjustment has to be recalibrated.

 

--The Full adjustment is a gain adjustment, and for best results it should be set on the Full mark with the full amount of fuel on the sender.  It's also possible, though typically less accurate, to use it to set the needle for 1/2 with half a tank, or something similar.  An error in setting at 1/2 will become twice as big at full, and an error in setting at 1/4 will become 4 times as big at full.  That's why setting at full is preferable.

 

--The Alarm output turns on when the gauge is reading 1/8 (nominally) or lower.  It is keyed to the gauge reading rather than a particular point on the probe.  If the Empty and Full are set correctly, the alarm should come on correctly.

 

2. DAMPED SENDERS

In late 2001 we began supplying Monaco with damped senders.  These respond slowly so that tank slosh wont be reflected in the needle reading.  However, each time the power is applied, the first 30 seconds will have normal response speed.  This allows the sender to get to its initial reading quickly.  It also gives time for calibration adjustments to be made.

 

A damped sender will have a 1" tall white label explaining the slow response after 30 seconds.  An undamped sender will have a 1/2" tall silver label which says nothing about slow response.

 

When calibrating a damped sender, you need to turn the power off and back on ("cycle the power") before each adjustment to get a new 30 seconds of normal-speed adjustment time.  For undamped senders there is no time consideration.

 

3. SETTING THE EMPTY

--If you need to remove the sender from the tank, it is best to make a tick mark on the sender and tank so you can get back to the original mounting orientation easily.

--"CTP" is shorthand for  "cycle the power to get 30 seconds of normal response speed if the sender is a damped one"

 

3a. Unless you shorten the sender, or there is a complaint about the Empty reading, or someone has already dug out the Empty adjustment, the brown-sealed Empty adjustment by Centroid will be completely trustworthy and you can skip to step 4.  If you feel the need to check the Empty, the sender can be lifted from the fuel (CTP first) whereupon the reading should be Empty.  Also, when you insert the sender into the fuel the reading should start upscale within the first half inch or so. 

 

3b. If the sender must be shortened, scratch the brown Permatex off the adjustment with a knife or something similar.  Be careful not to dig into the blue plastic of the adjustment .  A *small* bladed screwdriver is generally best for doing the adjustment because its easiest to push into the goo in the crosspoint of the adjustment screw.  Big screwdrivers often tear up the plastic of the adjustment screw.

 

3c. The adjustments are single-turn, so dont go past the stops.

 

3d. Start with both adjustments maximum CW.  The gauge should read above-Full (after CTP).

 

3e. CTP, and bring the Empty adjustment slowly CCW until the needle reaches the top edge of the Empty mark, rather than on or below the mark.  This top edge will keep you from overzeroing the adjustment.  (Once you adjust the Full, the Empty needle will have moved down onto the E mark at empty).

 

4. SETTING THE FULL

4a. Fill the tank and CTP.  The gauge should read above-Full.

4b.  CTP and bring the Full adjustment CCW until the needle is on the Full mark (not above it).  To be safe, CTP and check that the needle goes back to the Full mark.