Maintaining Your RVs Fuel System

If you don’t use your motorhome or any other vehicle regularly, you could have problems with aged fuel, whether diesel or gasoline. The problem is even more severe in warm climates, and humidity compounds the problem. Just so we start off with some good news, LP/propane does not deteriorate because it is in a completely sealed system so that the fuel is never exposed to air until the moment it is used. But diesel and gasoline go bad with age. Diesel fuel goes bad from microbes growing in it, and those microbes excrete water. The water and mucus-like sludge from dead microbes and their waste will clog fuel filters, and if enough water passes through the fuel filters it will also damage fuel injection pumps and fuel injectors which are very expensive. Prevent microbes from growing in your diesel fuel, and kill them if they are there, by using BioKleen by Power Service. Power Service products are available from truck supply or commercial marine supply distributors, or go to and select “automotive” and then enter “Biokleen”. By the way, it is prudent to always carry a spare set of fuel filters for your diesel. Some bad fuel can quickly clog the filters, which could have you sitting by the side of the road. If you have your own filters with you, it won’t be so hard to get a road service to come out and change them. Speaking of road service, Coach-Net is excellent for RVs, go to and click on their Coach-Net button for complete information. Join before you need help!

Modern gasoline is a real problem for vehicles that don’t use up the fuel in a couple of months’ time. Modern gasoline has ethanol in it, which absorbs water from the atmosphere. When enough water is absorbed, the ethanol and water separate from the gasoline and lay on the bottom of the tank. This is called phase separation. Guess where the fuel pump picks up the fuel from your tank? That’s right, at the bottom! So the crud that will clog up fuel filters and ruin expensive fuel pumps and fuel injectors gets sucked right in. Your goal is to prevent phase separation from happening. If you don’t expect to use-up your fuel within a couple of months and replace it with fresh fuel, you should add an appropriate fuel treatment to the tank. Fill up with gasoline, then add the fuel treatment before you drive to where the motorhome will be stored. That way, the fuel treatment will slosh and blend with the gasoline. You can buy fuel treatments at marine supplies distributors and fuel distributors. Be sure to read the bottle and make sure that it specifies that it will prevent phase separation. If it doesn’t say so, then don’t buy that product. Or it is easy to go to and select “automotive” and then enter “CRC PhaseGuard4 Ethanol Fuel Treatment”. Even if you use the best fuel treatment, you are pressing your luck if you let the old fuel stay in the tank for over six months.

In some areas you can buy gasoline without ethanol in it. To find a fuel stations that sell non-ethanol gasoline, go to Expect to pay 15 – 20% more than regular ethanol gasoline, not because it is so much more expensive to produce, but because it is a niche product. The gas stations that have it usually have a separate pump or separate nozzle that is labeled “Recreational Gasoline” because it is to popular with boaters for the same reason as RVers…they may go unused for months at a time. Some people claim that they get better gas mileage with the non-ethanol gasoline, which may help offset the higher cost per gallon. Keep in mind that if you are adding non-ethanol gasoline to a tank that still has some ethanol gasoline in it, you still need to use the fuel treatment to prevent phase separation. But the non-ethanol gasoline with fuel treatment added to it will probably be OK for up to a year in storage if there was only a little ethanol gasoline left in the tank when you filled up with non-ethanol gasoline for storage.