Fuel gauge accuracy

[The Danes Are Coming]

We have now had our fuel gauge calibrated twice by Monaco and once by a Monaco approved dealer in Phoenix, AZ. We can see from the various treads that we are not alone and we therefore wonder if inaccuracy is the norm.

[Nonno]

My gauge has been a problem since I got the MH last May. However, I didn't reply to the poll because I've never let it get that low.

I haven't had the sensor looked at yet. Figuring 9mpg my 75gal tank would get me 675mi but I choose to refuel around 300mi.

[CoolJudy]

We have a new '07 (first owners) Horizon and the first fill-up only showed 3/4 full on the guage. Then the low fuel light came on when we were registering about 1/4 tank. Hubby talked to either Winnebago or Freightliner and was told that full is about 80 gal. on our 100 gallon tank and that the light comes on when we have 25 gallons left. We know better than to get over confident on stretching fuels. It is just going to take us a while to get to know when to stop and fill 'er up.

[Hooter G]

From my experience and from reading on these forums, inaccuracy is normal in the Monaco fuel gauge sending units. They can be adjusted for "full" (the span) but not for "empty" (zero) as that is factory set. My dealer recommended against making a span adjustment. When I fill up, the gauge shows about 7/8ths full. I've never let my fuel tank get low enough for the light to come on. Just play it safe and watch how many miles you've driven.

[bullydogs1]

I've filled up my tank 3 times..gauge goes to full..when it reaches about 1/2 on a turn the gauge may go down to empty then low fuel light comes on and when turn completed it goes off and gauge goes up again. I am not fixing something that ain't broke--i'm leaving it.

[Diplomat Don]

Great Dane....I think it's difficult for the dealer to set the guage properly without filling the tank several times and knowing where it reads half full and so on. I monitored my readings for several trips and knew where my gauge (needle) was at when I was down 45-50 gallons. I then reset the unit by moving the needle that distance. My coach has a 100 gallon tank, but I doubt that I would get that much out of it. I am fairly confident when my guage hits half a tank that I've used 45-50 gallons.

As others have said, I don't go low enough for the light to come on for several reasons. One, I usually have to stop and pee long before then , two, I lose the ability to use the generator if I need it and I will only test the size of the tank to about 650-700 miles before I start to panick.

[Sixpack98]

I agree with Don. I played with the sender for a long time and still am not convinced with it accuracy. While the light never has come on, when I am at 1/4 tank I look for a station. I set the trip meter on the spedo and have little faith in the guage.

mark

[UPS 34]

Lets face it. Monaco has a JUNK fuel gauge. It should be a recall and replaced. Large trucks have gauges and work. Why is it a problem for Monaco. If you put Junk into the system.. Guess what you get. I just count the miles. I have had mine fixed 3 times. Still wrong. It has a mind of its own.

[walt2137]

A lot of our fuel gauge problems are connected to a faulty ground, I would suggest that you run a new ground wire and attach to a good ground. I will also past the Centroid adjustment procedure.

MonCal.doc
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.

[The Danes Are Coming]

Hi Walter

At the 3rd attempt to fix this problem they did run a new ground connection but this, sadly , made no difference whatsoever.

I am afraid that the only way seems to be to set the trip counter when fuelling up, and then do your own calculation.

[walt2137]

G Dane I agree, we run with a silverleaf program on our laptop and I use the fuel meter in that program for fill up, it gives us the gal needed to fill up along with a lot of other useful info.

Walt

[Pusherpilot]

Fuel usage is a diaphaneous subject.
Our coach has the Aladdin system, similar to the Silverleaf etc only integrated into the coach not operated from the laptop or add on display. The fuel gauge in our coach hasn't worked since we got the rig 5 yrs ago. Three attempts to fix it were unsuccessful.
We simply use the Aladdin trip computer which tels us what fuel has been used and add an appropriate amount for the genny and aquahot to determine how much fuel to try and get the coach to take. That depends on the "lean" when we fill it since the tank is 128 gal and the fill pipes don't allow for a complete fill. We count on having around 100 gal when we fill it and try to refill after the computer says we've run out around 60 gal. I've since pretty much forgotten that there is a fuel gauge on the dash. As it is I have to lower the wheel or rise up over the wheel to see it as it's on the botton of the display array and hidden from easy view.