Fuel Transfer Pumps and Water-Separating Filters
Move fuel from cans to engines without spills or sparks, and filter out water before it reaches your small engines.
⚠ Fill cans on the ground, never in a vehicle
Always set a fuel can on the ground before you fill it. Never fill a can in a truck bed, a car trunk, a flatbed, or on a trailer floor.[1][2][3] A can sitting on a bed liner or carpet can't shed static electricity, and a spark can light the vapor. This guidance comes from petroleum industry advice reprinted by Maryland's environment department.[1]
- Keep the pump nozzle touching the can while you fill, and fill slowly.[1][2]
- Don't get back in your car while fueling. If you do, touch bare metal on the car away from the fill spot before grabbing the nozzle again.[1]
- Turn off the engine and don't smoke.[1]
- Shut off a generator and let it cool before refueling it. Gas spilled on a hot engine can catch fire.[6][7]
- Never start a siphon with your mouth. Swallowing gasoline can be fatal.[1]
Pouring fuel from a heavy can into a small tank invites spills. A simple transfer pump and a filter that catches water make refueling cleaner, safer, and easier on your engines.
How much do I need?
One pump, one filter, one spare. Get one transfer pump per fuel type, one water-separating filter on it, and one spare filter element. Fill containers to no more than 95%: a 5-gallon can should get about 4¾ gallons (5 × 0.95).[1]
Picking a transfer pump
- Siphon pump: a hose with a squeeze bulb or shake-to-start valve. It moves fuel by gravity once it's flowing, so the source can has to sit higher than the tank.
- Hand pump: you crank or pump a lever. Good for moving fuel without power.
- Battery pump: runs on regular batteries and pushes fuel with a button. Easiest on your back. Keep spare batteries with it.
Whatever you choose, make sure it's labeled for gasoline (or whichever fuel you're moving), and never start the flow with your mouth.[1]
Why water in fuel ruins small engines
A little water dissolved in gas does no harm. Trouble starts when there's too much and it separates into its own layer.[5]
- Water is heavier than gasoline, so it sinks to the bottom of the tank, right where the fuel line picks up.[5]
- With most ethanol-blended gas, the separated layer is a water-and-ethanol mix. In two-stroke engines it can wash away the oil that protects the metal parts; in four-stroke engines it can make the engine run too lean and hot.[5]
- Water usually gets in as liquid, like rain through an open vent or a loose cap.[5]
Water-separating fuel filters
A water-separating inline filter is a small canister you put in the fuel line between the can and the tank. It traps dirt and pulls water out of the fuel so it collects in a bowl you can drain. Small engines already have a basic fuel filter whose job is to keep dirt and other contaminants out of the carburetor (the part that mixes fuel and air).[8] An add-on water separator gives you a second line of defense.
- Put one on your transfer pump outlet or the hose that feeds a larger tank.
- Check the bowl each time you transfer fuel and drain any water.
- Keep a spare filter element with your fuel gear.
Static and spill safety while transferring
- Work outdoors in fresh air, with both containers on the ground.[4]
- Keep the nozzle or hose end touching the rim of the container you're filling so static can drain away.[2][1]
- Go slowly. A slow fill builds less static and splashes less.[1]
- Leave room at the top: fill no more than 95% full.[1]
- Wipe up spills and let them dry before loading cans into a vehicle.[1]
- Keep a fire extinguisher nearby.[2]
Checklist
Mistakes to avoid
- Filling a gas can while it sits in a truck bed or trunk
- Starting a siphon by mouth
- Refueling a generator while it's running or still hot
- Leaving caps or vents open so rain gets into stored fuel
- Never checking or draining the filter bowl
- Topping cans off to the brim
Do this this weekend
Do a dry run: carry a can to your generator, set both on the ground, and practice hooking up your pump and filter (no fuel needed). Fix anything awkward now, while it's daylight and calm.
Gear that helps
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- Fuel transfer pumpsHand siphon / transfer pumpMoves fuel from cans to tanks without lifting and pouring heavy cans.Check it (opens retailer site)
- Fuel transfer pumpsBattery-powered fuel transfer pumpFills a generator tank steadily with less spilling.Check it (opens retailer site)
- Water-separating fuel filtersInline water-separating fuel filterCatches water and grit before they reach the engine, a common cause of no-start problems.Check it (opens retailer site)
- Water-separating fuel filtersWater-separating fuel funnelFilters water out as you pour, useful when fuel has been stored a while.Check it (opens retailer site)
- Fuel cans5-gallon approved gasoline canApproved cans are built to vent and seal safely; label each with the fill date so you rotate it.Check it (opens retailer site)
- Fuel cans5-gallon diesel can (yellow)Color-coded cans keep diesel and gasoline from getting mixed up.Check it (opens retailer site)
Sources
- Gasoline Safety Fact Sheet Maryland Department of the Environment
- Fire Prevention 52: Gas Cans National Park Service
- Storm Preparation: Have a Fuel Plan Florida Department of Agriculture and Consumer Services
- Home Hazardous Materials Fire Safety US Fire Administration
- Memorandum: Water Phase Separation in Oxygenated Gasoline EPA
- Generator Safety Red Cross
- Severe Weather Fire Safety US Fire Administration
- Chain Saw and Crosscut Saw Training Course, Chapter 3: Chain Saw Use and Maintenance USDA Forest Service
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