Fuel tank capacity Monaco Cayman 2003 Diesel

[Kidoo]

I would like to know how much fuel you put in your fuel tank? The book says 75 gallons. The other day, it was between empty and 1/8 and I added only 53 gallons. So this would be 22 gallons left to use, quite a good leg of travel. I am scared to take it down to Empty.

[Kidoo]

DSDP Don wrote:
Kidoo.....The Centroid fuel sending unit has everything incorporated into it, including the fuel pickup. On your coach, you have a panel on both sides of the coach, just behind the front wheels. I'm not sure if the Cayman had dual fuel fills, but the panel where your fuel door is located, actually opens.

On the driver's side panel, look under the coach and you'll see two screws holding some tabs down. Remove the screws and the entire pane with lift up, its hinged at the top and will take a broom handle to hold it open. Once you have it open. you'll see the fuel sending unit, about a 18" in from the edge of the tank, right on top.

Side Note.....I'm my Diplomat, I removed the screws on these two panels that access the tank and added a latch mechanism. There is a lot of valuable storage space atop the fuel tank. I use to keep tire chains and a blue toilet tote in there.

Here is the Centroid link for adjustment.

Thanks,very good info, I will check this out.

[DSDP_Don]

It's been years since I made the last adjustment, you may be right, two units near each other Centroid and pick up assembly.

[CA_Traveler]

The rest of my Centroid story: With a new 04 rig Monaco the gauge was not accurate and Monaco attempted to calibrate it twice. Before the second failed attempt I knew more than the Monaco factory service center. I knew they would not be successful since they never asked me to fill the tank.

OK maybe they extended the wires and used a bucket of diesel to calibrate the gauge, yeah right. :@

But Monaco fixed over 70 warranty items some of which they found. So good experience for me although it would have been nice for their QC to find the problems first. 🙂

Any then I could run to AZ to E and add 80 gallons to a 100 gallon tank not that I recommend anyone else try this. With kids in CA I did this often.

[CA_Traveler]

Don, Different than my 04 Endeavor which an separate Centroid and separate gen and engine fuel pickups and returns. Guess I'll check the current rig.

[DSDP_Don]

Kidoo.....The Centroid fuel sending unit has everything incorporated into it, including the fuel pickup. On your coach, you have a panel on both sides of the coach, just behind the front wheels. I'm not sure if the Cayman had dual fuel fills, but the panel where your fuel door is located, actually opens.

On the driver's side panel, look under the coach and you'll see two screws holding some tabs down. Remove the screws and the entire pane with lift up, its hinged at the top and will take a broom handle to hold it open. Once you have it open. you'll see the fuel sending unit, about a 18" in from the edge of the tank, right on top.

Side Note.....I'm my Diplomat, I removed the screws on these two panels that access the tank and added a latch mechanism. There is a lot of valuable storage space atop the fuel tank. I use to keep tire chains and a blue toilet tote in there.

Here is the Centroid link for adjustment.

[Kidoo]

Anyone knows where is the pick up tube? Is it sucking fuel up or is it draining it from the bottom of the tank?

[DSDP_Don]

We do the same thing....drive from the north end of Los Angeles and get fuel at the Pilot at the Havasu exit. Fuel up there on the way home too.

I don't think I ever pushed my Monaco past 60 gallons, and only on one occasion. 60 gallons was over 500 miles and a full days drive. I know a lot of people pulled the Centroid unit out to replace the generator pick up tube, making it longer. Monaco made it short so people wouldn't run out of fuel, but many feel it should have been up to them to monitor their fuel use. I know mine would quit working between a 1/4 and a 1/2 tank.

[CA_Traveler]

Don,

I agree that the Monaco tank design leaves a lot to be desired. If the gauge was in the center it would have a better side to side average but then it would be difficult to access w/o dropping the tank.

My main concern was knowing the tank level so that when leaving CA I could arrive on E into AZ, driving on a known road, normally I10. Fuel in AZ was $0.20+/gal less in AZ.

So my experience was different and I had no issues with the gauge vs the Monaco design.

[JimM68]

CA Traveler wrote:
On my 04 the gen ran out at 3/8 on the tank and the low light was just below 1/4 on the gauge. You may not have a low light, check the rig manual.

My '08 is just like yours.
Bother me sometimes that I can't use the genny unless I have LOTS of fuel.
And no matter how far I pushed her, never put more than 65 or 70 gallons in. DW gets a lil freaky when I push fopr the limits, so much as I want to know, I've no idea how much fuel I really have.

I kinda like Don's way of adjusting for half a tank.

[CA_Traveler]

On my 04 the gen ran out at 3/8 on the tank and the low light was just below 1/4 on the gauge. You may not have a low light, check the rig manual.

[DSDP_Don]

CA Traveler wrote:
The Centroids I've had are very accurate, repeatable and stable. The design is 2 concentric tubes and when the fuel reaches the bottom of the tube that is E on the gauge. The tube length is cut to length so that the gauge reads E when there is about 20% of fuel remaining in the tank.

I'll respectfully disagree. I'm not just repeating what I heard. I owned a Monaco Diplomat for 9 years and had to adjust the gauge twice. The Centroid may be an accurate gauge when used in a fuel tank that is not mounted in a vehicle, but when it's mounted in a motor home and especially a large side to side tank like Monaco used, it's far from accurate.

I adjusted mine and many others. They are easy to adjust from the driver's side fuel door panel, once you clean the undercoating overspray off.

To adjust, you need to note where the needle rests in different situations. I estimated about 80-85 gallons in my 100 gallon tank were useable. I wanted 40 gallons to be my half a tank mark. I noted where the needle was when I took 40 gallons of fuel. I also noted where my gauge was when it was full.

When you adjust the sending unit, turn on the ignition and give the needle at least 20 seconds to come to rest after each adjustment.

I eventually got mine to show a half tank when I reached about 40-45 gallons. With that said, the unit still jumped around to different positions at various times, but would more often come back to the same spot.

Lastly.....there are thousands of Monaco owners with the Centroid gauge that will tell you they are FAR from accurate or consistent.

My new coach (Freightliner) has a more compact 100 gallon tank that is longer front to back than side to side. It's mounted just behind the front axle between the frame and is FAR more accurate than the Monaco/Centroid unit ever was.

[dougrainer]

Kidoo wrote:
I did not know there was a low fuel light in these, it did not light up yet. I wonder how much fuel is left normaly when the light comes on. I saw a panel on top of the pass through over the tank.

I just want to make sure I do not panic when the light comes on. When I go south, I normally wait until I get to a cheaper place to fuel up.

There are 2 adjustment screws on the sending unit. 1 for the main fuel gauge level and the 2nd for the low fuel light level. Doug

[Kidoo]

I did not know there was a low fuel light in these, it did not light up yet. I wonder how much fuel is left normaly when the light comes on. I saw a panel on top of the pass through over the tank.

I just want to make sure I do not panic when the light comes on. When I go south, I normally wait until I get to a cheaper place to fuel up.

[CA_Traveler]

DSDP Don wrote:
Monaco uses a large side to side tank and a Centroid fuel gauge. Because of the design of the tank and the fact that the Centroids are not very accurate, your fuel gauge will be way off. The Centroid fuel gauge sending unit is adjustable, but takes some work to get it relatively accurate.

Monaco uses a shallow side to side tank and of course diesel sloshes in this type of design. Diesel engines stop immediately when then get air so you don't want to run the tank low on fuel. For this reason Monaco sets the gauge to read E when the tank is about 20% full. The generator pickup and low fuel light are above that point.

The Centroids I've had are very accurate, repeatable and stable. The design is 2 concentric tubes and when the fuel reaches the bottom of the tube that is E on the gauge. The tube length is cut to length so that the gauge reads E when there is about 20% of fuel remaining in the tank.

The Centroid can be calibrated. Fill the tank then pull the gauge out and set empty. At that point you can measure it's length and measure the tank to determine how much fuel is left when the gauge reads E. Reinsert the gauge and adjust for F. I did this at a truck stop and my 04 Endeavor Centroid was cut to read E with 18% fuel left in the tank.

Best to add fuel before the low fuel light comes on as the generator pickup will be above the fuel level.