Stuck Fuel Gauge

[barclay7568]

OK, got back from a long weekend trip and looked at my tank today. This in a 2004 Allure, 36', with a 135 gallon tank. Forward wall of forward bay, passenger side, opened the inspection panel, dusted off the top of the fuel tank, unhooked 3 wires and removed 5 screws, and pulled the sensor from the tank. I have 13.5" of clearance above the tank and tank opening of 1 5/8". As you lift the sensor, tip it toward the rear and it comes out the wall opening without any difficulty. Reading the directions on their website, they replace these with a 1/4" tube if less than 24" in length and mine is 17.5" with a 1/2" tube. Will call them tomorrow and order one. Price is $64 plus $9 shipping as near as I can tell.

Don, I bought this coach new in 2005 and my coach, when filled, stays on full for 150 to 200 miles. Then it slowly drops until it gets to half. The bottom half goes down more quickly and I usually refuel at 1/8 to 1/4, depending on where I'm at or going to and fuel availability. Even with these readings, 70 gallons fills me up so I still have 65 gallons in the tank.

I would assume CC calibrates these tubes when they're installed and they may set them a certain way so you don't run them out of fuel. The gauge I removed has calibrating screws on the top, and the Centroid website shows in their install instructions how to recalibrate the sensor if you choose to do so. I probably will leave mine alone as I maintain a log of each trip and I have a good idea of when I need to fill the tank.

RJPerry, are you sure that photo is the only access you have to the tank's top? I'd get under that rig and inspect with a bright light for an access panel you may have missed. Good luck.

Hope this helps.

[barclay7568]

Called Centroid last week and ordered a new sensor. Received it today by UPS and installed it in about 15 minutes. Before installation, I measured my tank and from the outside top to the bottom inside is 19.25". My sensor measures 17.5" from outside top of tank to the end of the tube. Seems to work fine and will fill the tank next week on a trip to verify it goes to full.

After I ordered mine, I called CC parts in Junction City and verified they had sensors in stock (per the phone call with Centroid). He looked up my chassis build sheet and told me I had a 110 gal. tank and a sensor of 18.25" length. I told them I was looking at my 17.5" sensor and everything I've read indicates I have a 135 gal. tank. He then checked at another building and called me back the next day and said I was correct with my figures. He indicated that sometimes the wrong data is entered into the build sheet at the end of each day and that is what happened in my case. He corrected the record for future reference. He does have sensors in stock of various lengths. He couldn't have been friendlier or more helpful.

I add this for those electronic techies much smarter than I. From the Centroid Products data sheet with the sensor: Centroid's sensors work by measuring the capacitance without moving parts. Electronics in the head convert this measured capacitance to the programmed output of ohms or volts. In fuel sensors, capacitance is measured between the inner sensing tube and the grounded outer tube, and the fluid must be non-conductive. In water sensors, capacitance is measured between the inner insulated sense wire and the water, with the water being grounded by a wire wrapped around the outer tube.

I read on their website that they make gasoline sensors for fuels with up to 10% ethanol but not above the 10%. I asked if bio diesel changes the reading I would get since bio diesel is all you can buy in Oregon. They didn't have an answer for me but said they would run it past their engineers who assist with their designs to see if the use of B5 or B20 may change anything about how they make the sensors.

For those who change out their own sensor, I recommend removing the old sensor and measuring what you have prior to ordering a new sensor.

Hope this helps those in need.