Always fill up the gas tank or ??

[MRUSA14]

Originally Posted by awol50

Fill up when you want. It's an old wives tale about condensation.

Maybe if you live in Arizona. Where I live in Florida, condensation is definitely a hazard.

[grindstone01]

Originally Posted by MRUSA14

Maybe if you live in Arizona. Where I live in Florida, condensation is definitely a hazard.

So who do you know that had trouble with condensation caused water in a fuel tank? Even a empty gas tank full of 25 gallons of air would only have a 1/2 drop of water in suspension at the max!

[jimmy braden]

Originally Posted by grindstone01

If your fuel pump is sucking air, you aren't going very far. Also, if over heating fuel pumps on empty were a problem, engineers would have easily fixed that issue.

YES you can. DI motors have HIGH PRESSURE pumps that are directly mounted on the engine. And throttle body FI only operates at like 40psi..

The intank pump can go easily 5 to 10sec at normal loads and not cause any motor effect.. But that doesnt mean the pump wont have a problem.

And they DID fix them- they created whats called bucket pickup assemblies.

https://ls1tech.com/forums/attachmen...s-dscn1899.jpg



.. but each manufacturer did it at a different point in the evolution of the model.. But feel free to test your model as you wish..

Originally Posted by twinboat

Yup, running low doesn't burn up intank fuel pumps.

I put 100,000 miles on my Kia, only getting gas when the low fuel light came on.

Has to do with how often the pump is uncovered.. in normal driving that might not be a problem depending on tank design.

I had a 1998 LEXUS GS400 and the intank pump failed at 62K miles after a routine process of running it to the low fuel light came on and then worrying about fillup.

[Fiesta48]

Run it down near empty? Heck NO. A hundred gal tank. Could be $250+!
Were in high humidity a lot. No way I want water in my diesel fuel.

[Darin1960]

Don't know if this was addressed, but on your first post you used the figure of fuel weight being 504 pounds and commented on carrying all that extra weight, but if you are filling only half you are only carrying 252 pounds. Carrying the weight equivalent to a large man wiil not significantly change you mpg. I have driven my pickup with nothing in the bed vs 300 to 500 pounds in the bed and see no real difference in mpg. On these motorhome the generally low mpg is attributed a lot to the less than aerodynamic design along with weight. Again to use my pickup as an example I generally get around 17 mpg. When I pull a 16 ft enclosed trailer which is 7 ft tall , I get between 11 and 12 mpg with an empty load. I think sometime ago I checked my mpg on my Fleetwood Revolution DP , with a tow and got 8.1 and with out tow 7.9 mpg and my tow weighed 4400 lb. This was on flat roads and only 1 trip. A .2 mpg difference on a 500 mile trip would result in about $4.40 difference and that is using a 4400 lb tow vehicle as an example so I tend to believe that the savings you are experiencing by reducing your weight by 250 lb's would be wiped out by the extra miles you would drive off the interstate ( more fuel stops) plus the inconvenience even if the fuel stop is right off the exit.

[A Traveler]

Originally Posted by Fiesta48

Run it down near empty? Heck NO. A hundred gal tank. Could be $250+...

So you do a $125 fill up twice. What’s the difference?

[SK1Retired]

I used to believe that BS about water condensation in less than full tanks. I stopped a few years ago it brought in more water sitting full. If your state uses alcohol like ours you are way better off emptier the better. Now I always add Lucas Marine Alcohol fuel stabilizer. Stops all the problems for $8 for every 40 gallons. It goes in the RV and boat and harleys. Alcohol is a much worse enemy. [emoji1360]

[grindstone01]

Yes, gas/diesel carries more water in suspension than air will. If the fuel sits long enough, the water will settle out. A full fuel tank is actually at a higher risk of ending up with water settling out during a long term storage.
Either way empty or full, it is a relative low risk that any water will end up in the fuel tank! This is the reason for the many success stories with either method of storage, full or empty.

[Ray,IN]

Originally Posted by TonyMac

My rig weighs over 28,000 pounds loaded. 500/28,000 = less than 0.018. We're talking about less than 1.8% of my total weight. I could not possibly care less, or better stated, I have a lot more important things to care about. I'd rather have the fuel for my genset than the immeasurable and unimaginable extra mpg.

It doesn't cost any more to fill the tank than buy a partial tank of fuel in the long run. It far outweighs the risks of water in fuel light shining in your eyes.
If fuel mileage was a concern of mine, I wouldn't be driving an over-sized shoe box.

[lwmcguire]

Originally Posted by wildtoad

You may find that your MH rides better with full fuel and full water, and has no real affect on MPG. Plus as others have said, better to have full fuel while in storage.

This is something that when driving on mountain roads or winding hiways having full tanks which lowers the center of gravity is certainly a plus

Certainly can't hurt the handling and likely does help

[mikena]

The change in mileage you realize, between a full tank and a partial tank, is going to be insignificant and probably not meaningfully measured.

[gsh-DP]

My father used to say “it’s just as easy to keep the top 1/2 full as the bottom 1/2”

You’ll never worry about running out of fuel and solve the condensation issues at the same time, and for those with generators that have 1/4 tank protection which kill the gen to not run you dry, no worries there either.

[tstep]

Originally Posted by RonRV.com

In order to watch my MPG on the class A RV we bought in March of this year I tend to always fill up when it half a tank or so. The 80 gallons of gas weighs about 504 pounds so for our short 2 to 3 day weekends at a state park 60 miles from home it seems I'm wasting some MPG carrying all that fuel.

Do most experienced RV'ers run with partial fillups? And then to see overall MPG fill up every so often.

There's no water hookup at this state park that we frequent so normally it's a full tank of water but this past weekend we've only used 1/2 which seems typical for a 2 night stay. I dumped the other 1/2 when we left and think I'll try filling up there instead of at home.

Thanks... Ron (2019 HR Vacationer 35P)

Ron, I have always kept my 80 gal. tank full, if possible, at all times. There are some very knowledgeable retired techs that follow this site and one of the things they recommend is keeping your tank full for the moisture build up. My 2001 Bounder, bought new in 2002 currently has 220,740 miles on it and I have not even had to replace the fuel pump yet. I am thankful.

[Captn John]

Arrived home yesterday and dropped the 5er. I have about 24 gallon left. Tomorrow I’ll fill the F350 and have 148 gallon capacity. I’ll pump all 124 gallon and just pay the bill when it comes. If not on the road I try to fill when I need 75-100 gallon. During hurricane season I generally top off at 30-40 gallon.