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RV Tech Savvy: Gas-tank Filling Problem

Originally Published in MotorHome Magazine

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We have a 2008 Chevrolet Class C motorhome and I have had trouble filling the gas tank ever since I bought it. The pump stops filling when I try to fill up. I have told gas station attendants that they had a problem with their pumps, and they told me the problem was with my RV. I also contacted GM, and they told me it was the gas pumps. I cannot even fill my motorhome, as it takes me 30 minutes to put 10 gallons in it. We have not used the coach since June because of the problem. We found out from a repair shop that the filler neck pipe is only 1 inch in diameter and by law should be 2 to 4 inches in diameter. I have contacted GM, my state’s attorney general and the coach manufacturer, but to no avail. We need to replace the tank and filler to the tune of more than $2,000. We have been told by the attorney general’s office to go to small claims court, but we have also been told that even if we win we will likely never see the money from GM. We feel this should be a recall issue.

Joe and Christine Savard | Huber Heights, Ohio

Answer iconRecalls are limited to safety concerns, and slow fuel filling probably does not qualify for a federally mandated multimillion-dollar recall. Your Class C is built on a GM van cutaway chassis. That means that it’s delivered to the motorhome builder with just a cab and running gear, with a bare frame aft of the cab. The fuel tanks and systems on these chassis have been around a long time, have been certified to meet Federal Motor Vehicle Safety Standards, and have been proven in thousands of fleets and in private use. I think the 1-inch hose you mentioned is a vent line, not a filler hose. Many of these situations spiral out of control because an owner who doesn’t understand how the system works takes the problem to a shop that doesn’t understand how to fix it. I do not dispense legal advice, only mechanical tips. A lawyer can charge you a lot of money, but will never fix your fuel-filling problem.

The motorhome manufacturer, which you didn’t identify, builds the body and installs the external fuel filler and plumbing to the tank. Most of the problems with slow filling turn out to be caused by the body installer. They are usually fairly simple, caused by a pinched hose; a hose that is too long and sags, allowing fuel to collect and block flow; or faulty vent-hose-routing prevents proper flow. If the air can’t escape from the top of the tank as it’s filled, the pump will kick off repeatedly. Also, when you are filling the tank, try rotating the filler handle and nozzle assembly to either side to find a different position. Often that is all that is needed.

Coach Current Draw

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I have two RV lots I rent. Last summer both 50-amp breakers failed. I suspect that the 50-amp breaker, which is only rated for 40-amp continuous use, is being overloaded by the big coaches with all of their extras like a washer/dryer. People may forget and not realize that it may not be feasible to have everything turned on at the same time. My question is, what is the load [amps] the large coaches with all of their extras can put on the 50-amp breaker? This potential problem would be magnified where the lot is rented for long periods of time. It may be that the power demands of the larger coaches have outgrown the power source.

Denver Isaacs | Leesburg, Florida

Answer iconIt’s quite possible that they were overloaded. I don’t know of any scientific statistical survey done to determine average usage. However, average usage wouldn’t necessarily be helpful because we’re concerned with peak usage by a small percentage of the highest power users. Did you take the old failed breakers apart and look at their contacts? If they were heavily burned, that increases the likelihood that they failed due to overload. Some of the larger luxury coaches do have many power-consuming appliances which could, if used together, surpass the 40-ampere continuous rating. Heating elements, such as hair dryers, irons and water-heater coils – along with space heaters and inverters/converters with battery chargers – all have high current draws. Dishwashers, washing machines and, of course, air conditioners have high draws as well. But in addition, when compressors, such as those found in air conditioners start up, they draw up to several times their running current. The 50-amp service was introduced to accommodate the heavier loads produced by newer RVs. A 30-amp service at 120 volts can provide up to 3,600 watts. A 50-amp system has a different 120/240-volt AC split-phase service, which means there are two 120-volt AC 50-amp poles, which can provide up to 12,000 watts (120 volts x 50 amps = 6,000 watts x 2 = 12,000 watts). So, the change from 30 to 50 amps doesn’t seem like much, but the difference is 3,600 versus 12,000 watts. However, this assumes that the loads are balanced between the two 50-amp poles. If most of the loads are on one side of the panel (on one breaker) there’s only 6,000 peak watts available, and to stay under 40 amps continuous that needs to be less than 4,800 watts. Therefore, it is essential for the loads to be balanced between both breakers in order to get maximum capacity and prevent overloading breakers. Unfortunately, you don’t have control over how the loads are balanced in coaches staying at your campground sites.

Tire-pressure Variation with Temperature

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Chris Quaderer’s “Inflation Pressure Versus Altitude” question in the October 2017 issue was good, but many of us live where weather temperatures also affect tire pressure. Living in Minnesota, the pressure can change 5 to 8 pounds from the summer reading when below-freezing temperatures occur. If one is a “snowbird,” keep this in mind.
Carl Wilkins | Via email

Answer iconThanks for writing, Carl. A good rule of thumb for tire-pressure variations due to air temperature changes is: For every 10 degrees Fahrenheit change, tire pressure will change by 1 PSI. For example, if the outside air temperature drops 10 degrees, the tire pressure will drop by about 1 PSI. For every decrease of 10 degrees Celsius, tire pressure drops by approximately 2 PSI. Or, 1.1 kPa for each 1 Celsius degree decrease in temperature (1 bar equals 100 kPa). When the temperature rises, the same thing occurs in reverse; as temperatures rise so do tire pressures, in the same percentages.

Leaky Light Tip

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This is in reference to the “Leaky Light” letter in the December 2017 issue, where you discussed finding a clearance light for a 2003 Winnebago. The authors (Joe and Gwen Russell) should try Transwest Truck Trailer RV (a Winnebago dealer), at 816-892-5941. Transwest tracked down a taillight lens for a 1998 Holiday Rambler for me. Also try Visone RV (606-843-9889, www.visonerv.com).

Bob True | Via email

Answer iconThanks for writing. Transwest is a franchised dealer for Newmar, Renegade, Roadtrek, Tiffin, Winnebago and Keystone, and has a number of locations. The Transwest location for the phone number you provide is in Belton, Missouri, and has 29 service bays. Visone RV is a salvage dealer that specializes in used parts, located in East Bernstadt, Kentucky.

Leaky Light Tip II

Question iconHave a tech question?
Regarding the “Leaky Light” letter in the December 2017 issue, I found a similar light at NAPA auto parts. It was marker light No. 25765y, with gasket No. 97701. Hopefully this will help the Russells and others with a similar problem.

Shawn Cannon | Via email

Answer iconThanks for providing this tip, Shawn. NAPA often has one of the largest selections of items like this.

Horsepower Differences

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We have a Class C motorhome on a Ford chassis with a V-10 engine rated at 305 hp. I also see Ford V-10s rated at 320 and 365 hp. How do they get the higher horsepower from the same engine?

Ron Swierski | Sun City West, Arizona

Answer iconActually, it’s a similar engine from the same family, but it’s not the same engine. The E-Series vans and cutaway chassis come with lower 305-hp ratings than the F-53 motorhome chassis because the E-Series has a smaller engine compartment. Ford has been installing V-10s with three valves per cylinder (two intakes, one exhaust) in the 6.8-liter V-10 since 2005. These heads flow more air and therefore can deliver more power. The E-Series vans still get the two-valve-per-cylinder V-10, which is the older design because of the greater width of the three-valve heads. The higher horsepower-rated engines also have different intake and exhaust manifolds. So, it’s not something that can be inexpensively changed.


Ken FreundRV DIYRV TechRV Tech SavvyTech topics

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