Eliminating Stopping for Fuel while Hooked Up.

I resolved one of Karen’s big travel concerns last week — and I must admit this fix does make it easier for me, too.

Navigating the truck and camper into some fuel stops can be challenging, especially for someone who doesn’t have a lot of experience towing something quite that large. I had been thinking about a possible solution that would alleviate this, but wasn’t sure how to go about it. Fortunately, the subject came up at one of the retiree breakfasts at Old South where I learned that Walt P____ had already implemented it on his rig as well as where he had it done.

My solution is a 45 gallon auxiliary fuel tank in the bed of the truck. I had it installed at a truck accessories shop in Adkins.

It’s a very simple setup. A line off the bottom of the tank runs to the truck’s normal fill nozzle. There is a ball valve and a check valve in the line. When the ball valve is open, diesel fuel will gravity drain to the normal fuel tank until it is full, when the check valve will stop the flow. (This gravity fill arrangement is prohibited for gasoline fueled vehicles because of flammability issues in an accident.) The tank has an overflow line to accommodate expansion if the fuel in the tank heats up.

A GM fuel system idiosyncrasy can cause problems when using an auxiliary fuel tank.

Apparently, based on fuel usage, the vehicle’s computer predicts when the tank should be empty and, at some point after that, shifts to run the engine in an economy mode, operating on only four cylinders. When running with the auxiliary fuel ball valve open, the level indication for the factory installed fuel tank will not change until the auxiliary fuel tank is empty, long after the engine would shift to four cylinders in operation. The resolution for this fuel system idiosyncrasy is simply to close the ball valve and let the main tank be drawn down and then, at the next travel stop, open the ball valve. The computer will see the rise in level as indication that the truck has been refueled and will reset its fuel tank usage calculation, as I understand it.

My plans are to operate. the valve periodically during the travel day.

Our fuel capacity will now give us at least a 650 mile range without refueling. This is quite a bit farther than we plan on traveling in a day. After we are at our day’s destination and have the camper unhooked and set up, we will refuel without having to navigate the camper through pumps and vehicles at the filling station.

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Update 3/5/2011 – The fuel idiosyncrasy never materialized.  It seems that computer simply resets the fuel expectations each time the engine is turned off.  The only thing I’ve seen strange is that if the economy seems to be improving, at times the fuel gauge will suddenly drop from full to empty and the  low fuel light will come on – always when still running with fuel in the auxiliary tank.

We still have the truck, though we traded the fifth wheel in for a motor home in 2008.  The auxiliary tank comes in especially handy when diesel fuel climbs in price like it is currently doing.  I filled the tanks all the way up a couple of weeks ago when the price was $3.49 a gallon.  It’s now over $3.75 and, since I am not working during the Unit 2 outage, the low price fuel should last several more weeks before I have to refuel.


A lost Exit78 post, recovered from Internet Archive WayBackMachine; March 2011


camping, economy, finance, recreational vehicles, travel, Uncategorized
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