Fuel Issue

[sport.pilot]

Originally Posted by onechaddude

Sport pilot. I went out to coach and measured tank and calculated numbers into formula. I came up with about 90 gallons all the way to the top of the tank. Obviously if you have looked at the filler spouts you cannot get the tank full. My guess to bottom of spout i come up with 73.867 gals to be exact. I guess thats where monaco gets the 75 gallon amount. I still do not believe you have a problem with your coach. If it cut off with you on a slope you could have easily still had 10 gallons or more in tank and starve the pickup given the size of the tank. In case you were wondering i measured the tank as 16" wide x 89" long x 15" high with about 12" high useable b/c of spout. Hope this helps you.
Chad

Thank you so much for your time and effort Chad. I called Monaco today and told them the issue. First question - were you on a slope? Answer yes. They said that was part of the problem. Low fuel + slope = greater probability of running out. I too was insight of the filling station. Unfortunately I did not know the issue. I now will carry an empty 7 gallon fuel jug with me at all times. Monaco said if the tank was sealed all around, it would hold 75 gallons, but it is not - it apparently is vented at the top in some fashion. It is vented at the top, and because of this, the filler tube is positioned to leave "room at the top" (I took this to mean air space). He said usable fuel was 58-60 gallons. His advice. when the needle was close to 3/8 mark, get fuel. He also said to be sure sending unit was good, and that the unit and gauge was calibrated when tank was "full". It would be nice if they put a decal or some indicator that said 75 gallons really means 60 gallons of usable fuel. It is just lime my ultralight experimental aircraft - tank holds 10 gallons, but only 8.7 gallons of fuel are "usable". When I fly it, I always start with a "full tank" and head home when it gets close to the 1/2 way mark.
Thank all of you that responded. Very helpful in solving what I thought was a mystery.

[onechaddude]

Glad i was able to help. This also will remind me to fuel up around quarter mark or above as well. If there is anything else i can help you with i will be glad to. My neptune is the holiday rambler version as your cayman so many things should be the same except you have the 6.7 isb where mine is the 5.9 isb. Happy travels.
Chad

[dajudge]

The safest thing to do is fill up when your guage gets down to one-quarter. The generator tube is shorter than the one for the engine for a reason. That being you cannot lower the level by running the generator to the level of the engine pickup.

[sport.pilot]

Yes, our is set up so that when the fuel level hits 1/4 of a tank (I wonder if that is of the total tank size of usable fuel) the generator shuts off. The Monaco guy said had I been on a level surface, I might have made it to the station. He also opined that since when I filled it up it took a total of 59 gallons, that I probably was out of fuel and that my gauge or sending unit was not working. The shop that is doing the work said the sending unit tested bad, and that the gauge was good.

[Dancing Bear]

Sport pilot. I have an 2008 Cayman xl . I also learned the hard way that the fuel gauge reads 1/8 when it is empty. I now drive by odometer. Did you happen to notice how far you had traveled when u ran out? I learned that we have a Max range of 500 miles with a full tank. So I go a Max of 400 then fill up. If I need to go further I can start the generator knowing it will stop @ a 1/4 tank. The filler necks will not allow anything near the claimed 75 gals. In addition, you may not be able to fill the tank equally from the driver side or curb side filler neck. On ours, the drivers side filler neck is at a lower angle which prevents me from putting in as much fuel as the curb side. Therefore, I fill from curb side filler only, unless impossible. You will also find that you want to use stations with level parking pads. If you use a station that has a pad slanted towards your filler neck, you will not get anywhere near a full tank. Hope this helps. From what you discribed my experiance is there is nothing wrong with your rig.

[sport.pilot]

John and Karen - thank you very much for the excellent tips. I will check our our filler tank tube heights to see if ours is the same - I assume it is. I generally fill from the drivers side, but I will check and fill from the side where the neck has the best angle. I never thought to check this. I did not check unfortunately how far I went, but I decided on a figure of about 8 miles to the gallon which would get me about 480 total. So, I too decide to go about 400 and then fill up. I will keep the level pad in mind when I fill up. It would seem that I want the pad at the station to tilt away from the side I am going to fill with to get the most amount of fuel in. Most seem to be pretty level however. Maybe I will put a cheap level in the coach to use - any advantage in filling is worth the effort. I am sure I will get some strange looks when I put the level down! Thanks again.