Where the heck is the fuel gauge calibration screw???????

[bluebarry1964b]

2003 Holiday Rambler Neptune: I was told that if I remove the driver's side basement panel where my fuel door/cap is that I will find a screw on the sending unit and can adjust the screw in order to calibrate my fuel tank gauge, which is reading WAY too full.
Spent two hours working on it as it didn't go the way it was supposed to (isn't that always the case). Finally got to where I needed to be only to find---nothing. Just the fuel line running from the fuel cap to the tank, nothing else.
Has anyone out there adjusted their fuel gauge on a similar RV who can tell me what the sending unit looks like and, hopefully, where it is? Thanks.

[wa8yxm]

Three words or I have NEVER heard used together in the automotive world before this discussion are "Fuel Gauge" and "Calibration" .

I did not think there was such a thing as a calibrated fuel gauge outside of perhaps aircraft.

[DSDP_Don]

In case you didn't discover this, most panels on Monaco coaches where the fuel door is located will open. Some fill doors are mounted in bay doors that swing open and expose the fuel tank, but many are mounted in a panel that is not a bay door and doesn't look like it would open. The non bay door types do open and swing up. You have to look under the bottom edge of the panel and you'll see a single screw, remove it and the panel will lift up. You'll need a broom handle to hold it open. All the Monaco fuel gauges that I adjusted were always on the driver's side.

Here's Centroid's literature. Keep in mind, every time you make an adjustment, you must turn the key off for 30 second and then check.

Centroid

[Ozlander]

mowermech wrote:
Thanks. Since I have never owned a Monaco of any kind, I did not know that. My statement was based, as always, purely on personal experience.
I learned something today.

Yeah, us common folk just put up with what we get.

[mowermech]

dougrainer wrote:

mowermech wrote:
The only way I have ever been able to "calibrate" a vehicle fuel gauge is to remove the sending unit, bend the float arm, and reinstall the unit. Repeat as necessary until the desired calibration is achieved.
The sending unit will very likely be in the top of the tank, approximately in the middle. Since the manufacturers usually are not smart enough to build an access panel in the floor, the only means of access is to lower the tank.
Good luck.

This thread applies to Monaco ROADMASTER chassis fuel systems. ONLY Roadmaster designed their tank senders with an adjustment POT accessible without removing the tank. Freightliner/Spartan/Ford/Chevy/Workhorse have no such adjustment system. Doug

Thanks. Since I have never owned a Monaco of any kind, I did not know that. My statement was based, as always, purely on personal experience.
I learned something today.

[bluebarry1964b]

This is the OP: You people are incredibly helpful. You're always my first source of advice when I'm running into problems. I always know that SOMEBODY out there will have run into the same issue and be able to assist. Thanks so much!!!

[CA_Traveler]

Good input from Doug. Make sure the rig is level when filling and level when checking the full POT.

I first removed the sensor and checked that the empty POT was set correctly, it wasn't. The sensor is highly damped except when first turned on. So DW turned the ignition off/on while I made the full adjustment.

[dougrainer]

mowermech wrote:
The only way I have ever been able to "calibrate" a vehicle fuel gauge is to remove the sending unit, bend the float arm, and reinstall the unit. Repeat as necessary until the desired calibration is achieved.
The sending unit will very likely be in the top of the tank, approximately in the middle. Since the manufacturers usually are not smart enough to build an access panel in the floor, the only means of access is to lower the tank.
Good luck.

This thread applies to Monaco ROADMASTER chassis fuel systems. ONLY Roadmaster designed their tank senders with an adjustment POT accessible without removing the tank. Freightliner/Spartan/Ford/Chevy/Workhorse have no such adjustment system. Doug

[dougrainer]

Just remember, have the tank full at the first click release on the fuel nozzle and do not keep filling as another stated. When adjusting, WAIT for at least 1 minute before attempting the next adjustment. The Dash needle moves VERY SLOW when adjusting. It can take up to 15 to 20 minutes to do the full calibration because you need to wait for the needle to move and then stop. Rushing will just cause a longer time to get it correct. Doug

[drwwicks]

Just don't confuse full with, "unable to pump more in". As many have stated on posts, when the fuel nozzle clicks off, I am at about 7/8th+- on the gauge. If I go slow and take a while, I can get another 15+- gallons in and the gauge reads full then. I would recommend against setting gauge to full based on fuel nozzle and tank venting antics.

[BigSkyBob]

Twomed wrote:
Look for the sender on top of the tank...usually passenger side, but varies by coach. About hockey puck size with four wires. Directions below are from the Monaco manual. VERY SMALL adjustments. Good Luck 🙂

Fuel Sender
The "Centroid" fuel sender has no moving parts and works by
measuring capacitance (electrical property) between inner and
outer tubes in the tank. The more fuel between the tubes, the higher
the reading. Electronics in the "hockey-puck" head of the sender
convert the capacitance to current to drive the fuel gauge.
Connections:
The "Centroid" sender has four connections:
1 & 2 - Positive (POS) and Negative (NEG): Battery voltage
to run the electronics in the sender head.
3 - SEND: Connects to the SEND terminal of the gauge on the
dash.
4 - ALARM: Makes a connection internally to the negative
(NEG) terminal when the low fuel alarm level is reached
(when the fuel gauge is reading about 1/8 tank). This turns on
the fuel indicator light on the dash and is not adjustable.
Adjustments:
The "Centroid" sender has two adjustments:
1 - EMPTY: Adjusts for length of sender. It has been set at the factory, covered with a
sealant and should not be changed.
2 - Full Adjustment (FULL): The full adjustment can be used to correct for slight differences
between fuel meters. During installation, it has been factory calibrated and should
not need re-adjustment.
The correct adjustment technique, with a full tank of fuel, is to start with the full adjustment screw
completely clockwise. This should cause the reading to be above full. Adjust slowly, rotate counterclockwise,
until the full mark on the gauge is reached. The intent is to always adjust downscale rather
than upscale.

This is exactly how the factory tech adjusted mine. I stood there to see how they did the procedure. Mine was reading full at 3/4 now it's very close to actual volume. My tank was full when it was adjusted.

[Twomed]

Look for the sender on top of the tank...usually passenger side, but varies by coach. About hockey puck size with four wires. Directions below are from the Monaco manual. VERY SMALL adjustments. Good Luck 🙂

Fuel Sender
The "Centroid" fuel sender has no moving parts and works by
measuring capacitance (electrical property) between inner and
outer tubes in the tank. The more fuel between the tubes, the higher
the reading. Electronics in the "hockey-puck" head of the sender
convert the capacitance to current to drive the fuel gauge.
Connections:
The "Centroid" sender has four connections:
1 & 2 - Positive (POS) and Negative (NEG): Battery voltage
to run the electronics in the sender head.
3 - SEND: Connects to the SEND terminal of the gauge on the
dash.
4 - ALARM: Makes a connection internally to the negative
(NEG) terminal when the low fuel alarm level is reached
(when the fuel gauge is reading about 1/8 tank). This turns on
the fuel indicator light on the dash and is not adjustable.
Adjustments:
The "Centroid" sender has two adjustments:
1 - EMPTY: Adjusts for length of sender. It has been set at the factory, covered with a
sealant and should not be changed.
2 - Full Adjustment (FULL): The full adjustment can be used to correct for slight differences
between fuel meters. During installation, it has been factory calibrated and should
not need re-adjustment.
The correct adjustment technique, with a full tank of fuel, is to start with the full adjustment screw
completely clockwise. This should cause the reading to be above full. Adjust slowly, rotate counterclockwise,
until the full mark on the gauge is reached. The intent is to always adjust downscale rather
than upscale.

[CA_Traveler]

BTW Each diesel engine with have 2 hoses to the tank top, perhaps near the sending unit.

[CA_Traveler]

A common Monaco setup has the Centroid sending unit outside the rails on one side, look for wires on the top of the tank. There are 2 adjusting screws and instructions on their website.

[mowermech]

The only way I have ever been able to "calibrate" a vehicle fuel gauge is to remove the sending unit, bend the float arm, and reinstall the unit. Repeat as necessary until the desired calibration is achieved.
The sending unit will very likely be in the top of the tank, approximately in the middle. Since the manufacturers usually are not smart enough to build an access panel in the floor, the only means of access is to lower the tank.
Good luck.