RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 09-22-2019, 08:41 PM   #71
Senior Member
jimmy braden's Avatar
Texas Boomers Club
Holiday Rambler Owners Club
Join Date: Jun 2002
Location: What? Like right now? ;-)
Posts: 1,090
Originally Posted by Max Hubrich View Post
I'm in a gasser and I want all the "cooling" I can get for my in-tank fuel pump.
thanks for making it easy ace...

glad that CAI and colder plugs are working for you .. ;-)

Ultra Power upgrade, CAI (cold air intake), Taylor wires, colder plugs, Koni shocks.

2003 Scepter 40PDBB - Roadmaster rr8s - Cummins ISC350 - purch aug16
jimmy braden is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 09-22-2019, 10:19 PM   #72
Senior Member
Join Date: Nov 2005
Posts: 3,472
As others said you do not want to run low on gas since there are water vapor, sediment, etc issues and since most since the 1990's are fuel injected you do not want to come anywhere close to running the fuel pump without a good covering of fuel in the tank to cool it.

Less than half a tank and your too close to that magic mark where the fuel pickup for your generator will be sucking air too and the generator stops running. If the generator pops and sputters as it runs out of fuel it can damage the seal on the two halves of its intake manifold which can cause it to run hot or only on one cylinder which is quite costly to repair.

Most fuel injection pumps are lubricated by the fuel so running them on the dregs or dry can lead to premature fuel pump failure which is a very costly repair especially if its a submerged pump inside the fuel tank which will often add the cost of pumping out and dropping the fuel tank in order to replace it.

Even if the Fuel Sock/Fuel Pump Inlet Filter gets clogged you can find yourself paying more to have the fuel tank drained and dropped than for the actual Fuel Sock.

More reasons to keep the tank as full as possible rather than just carrying the bare aluminum.

Neil V
2001 Winnebago Adventurer WFG35U
NeilV is offline   Reply With Quote
Old 09-22-2019, 10:26 PM   #73
Senior Member
Join Date: Sep 2016
Posts: 967
Originally Posted by bobfrommaine View Post
If you record your fuel and miles drivn, then when you finally DO do a fillup, you will be able to calculate your fuel MPG. You don't have to fill up every time. I carry at least 1/2 tank of water, have the black and gray tank around 1/4 to 1/2 full and keep the fuel tank as full as possible. I get really nervious wen I get down to 1/3 a tank of fuel, so fill up as close to half a tank as possible. Plus I HATE getting my fillup interrupted by the magic $100 limit on most pumps.
Bob '14 Winnebago Adventurer, Jeep toad
Just put the cc back in and start over. Takes all of a minute or so.
Brian & Jennifer K.
2016 Winnebago Forza 36G
Pushed by a 2003 Chevy Tracker
awol50 is offline   Reply With Quote
Old 09-22-2019, 10:37 PM   #74
Senior Member
Join Date: Sep 2016
Posts: 967
Originally Posted by bayrider View Post
I consider water (a good deal heavier than gasoline) and gas fill levels only when I have extended climbs over mountain ranges ahead of me. I will notice a difference in uphill performance and we are fulltimers running fully loaded. It's certainly good practice to dump the dead weight in the waste tanks, maybe hold off on water fillup. Nothing feels better to a redblooded American motorist than a full tank but more important is filling in NV or AZ and as little as possible in my former home state CA.

If you want fuel 'economy':

1. Get a Pentagon Federal Credit Union Visa card and use it for all fuel purchases, you get approx a 5% rebate on unlimited fuel purchases. Also use it for all grocery purchase, it's approx 3% on those. I get 5 or 600 dollars a year in tax free rewards with this card. You don't need to be military either.

2. Shop at Krogers supermarket brands, there are a number I know of, Frys, King Sooper, CitiMarket, etc. You get fuel points up to $1 per gallon, up to 35 gallons at their station or at QuickStops, Circle K, Shell, etc. An RV is exactly what you want when you pull up to the pump with a $35 / 35 gallon discount! A few weeks ago I got 35 gal at a $1 discount, then restarted the pump and got another 28 at a .40 discount at which point the tank was full, I felt cheated out of the last 7 gallons. But I left feeling pretty smart anyway! Kroger's stores and store brands are also the best in my experience.

*For bonus points use your brother's phone number as your alternative ID at the pump. You know, the one who's wife shops at King Soopers religiously and never bothers to use the fuel rewards. We get their rewards across 3 or 4 states, UT, AZ, NV, CO, but no deal in CA as far as I know.
I probably have not bought 50 gallons of fuel in the past 3 years without getting $1/gallon discount at Kroger/Fred Meyer gas stations out here in the northwest states for all my vehicles and diesel RV. From Western Montana to all of Washington and down into northern California. With an easy 750 mile fuel range in the RV helps.
I keep track of my savings. Averages a little over $1,000 a year for past 3 years at $1/gallon discount.
Brian & Jennifer K.
2016 Winnebago Forza 36G
Pushed by a 2003 Chevy Tracker
awol50 is offline   Reply With Quote
Old 09-23-2019, 05:53 AM   #75
Junior Member
Join Date: Jun 2018
Posts: 28
I just like to know, gives my mind something to think about in a 12 hour drive. Also sudden drops in mileage can give you a heads up on some mechanical issues. Same as when I used to fly, what’s the point in hauling around stuff you don’t need.

That being said I have discovered my coach rides a lot better with some weight in it so I have taken a hit on mpgs for a better ride. (But I do still keep track of it). I fill the h20 and will fill the gas tank after I am through the mountains in West Virginia.
Crazedfooter is offline   Reply With Quote
Old 09-23-2019, 07:25 AM   #76
Senior Member
michealwhela's Avatar
Tiffin Owners Club
Retired Fire Service RVer's
Join Date: Apr 2014
Location: Traverse City, Michigan
Posts: 169
Blog Entries: 25
Keep it full

We keep it full. As soon as we drop below a half I start watching for the best fuel price to fill up. I did an experiment with weight using my fresh water tank. Checked my mpg and performance with no water on board for a tank and then checked it with a full 90 gallons of water on board. End result was no significant difference. Admittedly this was only for one tank and there may be a notable difference over a year of traveling. But I like the comfort of having fuel to spare when my comfort and safety require it.
Mike Whelan
2017 Tiffin Allegro Breeze 31BR
Retired firefighter and police officer
michealwhela is offline   Reply With Quote
Old 09-23-2019, 07:28 AM   #77
HISSSSS's Avatar
Join Date: Apr 2019
Posts: 55
Condensation in a steel tank overnight is real

Try this little experiment:

Put an empty metal tea kettle outside in the heat of the day.
After the night time temperature drops 10+ degrees, in the morning is there liquid water in the kettle?

Physics/ psychrometrics tells us it will. If vented to the atmosphere, it will contain more liquid water in the morning than if it was sealed as more moisture laden air can enter. When sealed, it will be less as the total mass of water in the kettle is constant, just some of it will condense.

Now add in fuel the whole chemistry problem inside your tank gets more complex. Is the fuel hydroscopic and how much? (i.e. Ethanol gas and diesel fuel both absorb water) How to minimize this during temperature swings? Simply reduce the vapor volume in the tank.

Whether you think condensation is a myth or not, keeping your tanks full is wise as you never know when you will need to use fuel. What good is a RV or a generator if has no fuel? My generator stops working at a quarter of a tank of diesel which means boondocking will be curtailed as I don't yet have solar.
'12 Winnebago Via 25T, stock except: HWH Levelers, NovaKool RFU68000 12V Fridge,Group 31 AGM Coach Batteries, PM4 55A 55 Amp Converter, PI EMS-HW30C Surge Protector, Michelin Agilis CrossClimate Tires, TST Internal TPMS, Borg Stems, Sumo Springs
HISSSSS is offline   Reply With Quote
Old 09-23-2019, 09:04 AM   #78
Join Date: Nov 2017
Location: Manchester, Tn
Posts: 86
I understand you’re talking about gas and not diesel, with today’s gasoline having 10% ethanol it will attract moisture, so if you leave your tank low on gas you’re inviting water into your tank. Your fuel system has a fuel return line that returns unused gas back to the tank, this gas has been heated by the fuel system as it past through the system, now you have hotter fuel temperatures than the outside air temperature, as this cools it pulls cooler air into the tank this air also has humidity (water) in it. As this cools the moisture condenses on the tank wall, now you have water in your gas. I always fill my tank before going into the campground, of course we are stopped for several months, but it doesn’t leave room for moisture, and if severe weather should come in I can be ready to leave in 30-45 minutes and have enough gas to drive 450 miles before needing gas.
Robert Pulliam
2002 Newmar Mountain Aire 38’
2017 Chevy Equinox toad
Grandpa5x is offline   Reply With Quote
Old 09-23-2019, 09:33 AM   #79
Senior Member
grindstone01's Avatar
Join Date: Oct 2017
Posts: 3,619
Do you know of anyone that has actually had water condensation in their fuel tank?? Tanks are sealed and the only fresh air allowed in them is to displace the fuel being used. I would not be too concerned about the fuel pump overheating concerns, 12V DC motors just don't run that hot (especially motors designed for inside a fuel tank). Besides the fuel tank would have to be totally empty for pump to be exposed.
I agree that having a full fuel tank is a good choice for being prepared for whatever might happen.
Attached Images
2018 Chevy DRW
2008 Carriage Cameo, F34CK3
Full Time since 2012
grindstone01 is online now   Reply With Quote
Old 09-23-2019, 10:29 AM   #80
Junior Member
Join Date: Oct 2018
Posts: 28
Where do 'old wives' tales come from?

Please, condensation problems and fuel pumps failing all across America? And even the generator will be damaged if you let it run below the feed line? I don't think so. These issues have been engineered out of vehicles decades ago with possibly rare exceptions.

I can't speak to diesel but as far as gasoline goes these are non issues. We've had our 20 year old F53 for 12 years now. Before fulltiming I preferred less fuel in the tank for winter storage because then I could throw 2 cans of Seafoam in the tank instead of six, most years I didn't even bother with that. What's more important is starting engines and generators up on a regular basis.

Our range is from 450 to 600 miles per tank depending on terrain, wind, speed conditions. There is at least 100 miles in the last 1/4 tank, why on Earth would I not use it? We range constantly through very remote areas and off pavement. To get here we drove from Reno via US 50 'the loneliest road in America' over probably a dozen basins and ranges, then across remote parts of UT. Less fuel stops than in 98% of the USA yet easily within the range of this RV. This early model V10 runs great but up and down those mountains it is taxed to it's limits, I prefer less weight in general. I've detached and had the wife drive the Subaru behind several times this year, like pulling out of Death Valley through the Panamints 20 mile grade in 114 degrees.

We are boondocked this very moment on a BLM land high mesa near Dead Horse Point outside Moab. With a half tank. My only concern on fuel is having enough to run the generator for the morning coffee brew and intermittent microwave use through the approx 3 weeks we'll be here before we need to head downtown to dump the black tank. I will try to time that with my main criteria for filling up - when our kroger fuel points hit $1.

I have had a couple instances of water in fuel from service stations but those were decades ago. I was convinced I got water in the gas at a fillup in Baja last winter but it turned out to be a coincidental breakdown of an O2 sensor that would cause the engine to intermittently run rough and lose power. We pulled the filter and could not find any water in a quart we drained. Also could not get the O2 sensor in Baja. Eventually it failed completely and the engine apparently reverts to a fixed program where it runs fine but with a check engine light. I have since replaced both sensors but I could swear the engine ran stronger with the fixed program.

Next someone will be telling us that a Fram oil filter will be the death of our engines (it won't be).

Now I will get back to obsessing on the really important things, like the tire and suspension pressures on our mountain bikes before we hit the slickrock trails again today...
bayrider is offline   Reply With Quote
Old 09-23-2019, 10:45 AM   #81
Junior Member
Join Date: Oct 2018
Posts: 28
Originally Posted by awol50 View Post
I probably have not bought 50 gallons of fuel in the past 3 years without getting $1/gallon discount at Kroger/Fred Meyer gas stations out here in the northwest states for all my vehicles and diesel RV. From Western Montana to all of Washington and down into northern California. With an easy 750 mile fuel range in the RV helps.
I keep track of my savings. Averages a little over $1,000 a year for past 3 years at $1/gallon discount.

Yes, it adds up. Get the PFCU Visa and add that 5% on top of the Krogers discount.

Use PFCU for all fuel and groceries.

For all other purchases and bills I use a CitiBank Double Cash Mastercard, 2% rebate on all purchases and services, that one is generally good for $75-100 rebate per month for us and we have fairly low spending.

Neither card has annual fee, of course we autopay in full from checking every month.

I love free money, especially tax free free money. We used to get a ton of airline miles from other cards, will get back to that later after the dog passes on...
bayrider is offline   Reply With Quote
Old 09-23-2019, 11:43 AM   #82
Senior Member
Join Date: Aug 2011
Location: Western New York
Posts: 668
From my years of boating on Lake Erie, I trained myself and family to always consider a half tank of fuel as an empty tank. What that meant was filling the 50-gallon tank up before every trip so not to get caught out in a huge lake out of gas. It also worked as a reminder that when we were enjoying a day of boating it was time to start thinking about heading back to the home marina when the gas was nearing a half tank. Over ten years of boating we never had to be towed back to port, but, boy how many boats did I pull in, especially the few less than one mile away from Niagara Falls!

This is the practice I have been using since my DW and I bought our first class A twelve years ago. Almost always I will fill up the rig the night before a trip, short weekend or longer at our local Speedway one mile from home. While on the highway I will start looking for a place to fuel up, and bathroom break, at a half tank. Sure at times, I won't be able to stop until I have less than a half, but the gauge is on my mind as we approach each exit ramp. Since we switched to a DP in May I find this even more beneficial with diesel not as easily available as 87 octanes. I just feel more secure in knowing the tank is full. As a side physiological point, it seems like I'm spending less on fuel filling half tanks or less instead of 80-85 gallons waiting for it to be near empty
Vincee & The Fabulous Miss Barb
2014 Cross Country 360DL DP
Kia Sportage on a Master Tow Dolly
vincee is offline   Reply With Quote
Old 09-23-2019, 01:08 PM   #83
Senior Member
Join Date: Nov 2005
Posts: 3,472
Originally Posted by bayrider View Post
Please, condensation problems and fuel pumps failing all across America? And even the generator will be damaged if you let it run below the feed line? I don't think so. These issues have been engineered out of vehicles decades ago with possibly rare exceptions.


I maintain vehicles and boats and I can assure you that its not an old wives tale. It costs us thousands of dollars every year cleaning up other peoples messes from fuel tank condensate and the resulting ethanol separation creating white foamy/soapy sludge in the fuel tanks.

Its pretty well known the the Onan Marquise 5,000 has a clam-shell intake manifold that is bonded together and Onan techs will admit that its very common for those intakes to loose their bond after a low fuel backfire event.

We also hear of people on this board having to either drop their fuel tanks or cut a hole in their floors to access and replace a failed fuel pump or clogged fuel sock too.

There are also a lot of very busy fuel system polishers out there cleaning up fuel tanks and replacing fuel pumps that have failed across the US for a Old Wives Tale. This also impacts operators of gasoline stations who need to have their tanks cleaned with some installing built in polishing systems to keep the fuel circulating and trap any algae, etc growing in the ethanol fuel.

Ethanol is at the root of all this and if you have ethanol fuel thats been sitting untreated you will be having some level of contamination. Even treated Ethanol is only good for 2 years before it starts phase separation while insufficiently treated it can absorb enough moisture though the tank vent to phase separate in very short order especially if you are in a very humid area such as South Florida and your tanks not very full.

Face it too that many 30 year old motor homes are still on the road today. Its not uncommon for a new user to join this forum after having just purchase a late 1980's to mid 1990's coach and those coaches can face issues from fuel lines and seals that are not ethanol resistant.

New vehicles are not immune to phase separation and other ethanol related issues either and this will likely only stop once they stop producing ethanol. The only thing they have really engineered out of newer vehicles is using fuel lines, seals and gaskets that either dissolve or swell up when exposed to ethanol.

Newer fuel injected generators add a new wrinkle in that the impellers on the high pressure injector pumps can fail when run dry making it more critical to not allow your fuel level to drop below the generators fuel pickup.
Neil V
2001 Winnebago Adventurer WFG35U
NeilV is offline   Reply With Quote
Old 09-23-2019, 01:34 PM   #84
Senior Member
RELHUB's Avatar
Join Date: Aug 2011
Posts: 389
When I return from any trip I always fill up.
I am more concerned with saving time for the
START of our next great Adventure.

This is something I have always done but never thought much about the real benefits of this practice until Hurricane Sandy.
We were unable to get gas for 5 days and if you could find some the lines were hours long.

We had to live in our MH for 10 days and because the tanks were full,
we were able to run our Genset almost non stop and still had plenty of fuel.

GRV We love to Roam
2013 Georgetown
RELHUB is offline   Reply With Quote

gas, tank

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Why Do I Always Have 25-30 Gal Remaining Before A Fuel Fill-Up? rag_ftw Travel Supreme Owner's Forum 19 03-13-2018 08:31 AM
Odd behavior, couldn't fill up gas tank wplate MH-General Discussions & Problems 5 06-22-2014 08:36 AM
2007 E-450 Gas Tank Fill Problems fayrankin Class C Motorhome Discussions 1 05-28-2010 08:10 PM
Onan Genset 5500 gas HGJAB model not starting always udbe2 RV Systems & Appliances 9 05-19-2009 07:55 PM
Can't fill the gas tank tsmit32 Ford Motorhome Chassis Forum 16 08-04-2007 07:58 AM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 10:21 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.