Fuel Cap Cleaning

Removal of the fuel cap

Step One: Removal of chain

Step Two: Loosen cap to open position

Step Two: Marking tab for proper re-assembly

Step Three: Removal of pivot pin

Step Five: Removal of hex nut for breather

Step Six: Removal of rubber breather flap

To optimize system operation, our fuel cap has a built in breather allowing the tank to draw in air to displace fuel drawn out of the tank. The tank is also outfitted with a pressure relief valve to relieve potentially dangerous positive pressure. Both breather and cap should be cleaned periodically through general use. The pressure relief can be easily wiped down when you fill up (make sure you can pull the piston up).

The breather in the cap should be cleaned whenever tank experiences excessive vacuum(which makes the engine labor, essentially acting like a clogged filter). This would also show up as a characteristic vacuum when trying to remove the fuel cap as well. The cap can be simply cleaned following the steps provided.

Step One: Remove the chain from the bottom of cap. With the cap removed from the tank, access to the internals will be much easier. Using a pair of pliers, remove the cotter pin from the cap, and remove the chain.

Step Two: Loosen the cap to the "open" position. This is the position the upper tab would be in when you would open the tank. Note the direction the tab is in, and which side of the tab is normally "down" when the cap is secured to the tank. The tab is held into the post via the small metal rod the tab pivots on.

With the tabs lined up (see photo), mark one "set" of tabs. This will allow you to realign the cap correctly upon reassembly.

Step Three: Remove the pivot pin, tab and retaining washer. Depending on the condition of the cap, it may take no more than a paper clip to push the pin out. If there is buildup on the cap, it may require something more stout, like a thin nail. This is also easier if the two "halves" of the cap are pressed together, as this will take the clamping pressure off the tab.

Step Four: Separate the upper and lower halves of the fuel cap. These should come apart fairly easily. There is an o-ring on the center shaft that may gently hold the caps together. The two halves should separate easily. Twisting the cap can help separate it as well.

Step Five: Remove the hex nut and breather cover from the top of the cap. This is held to the cap via a 1/8" allenhead machine screw. Simply unscrew it from the cap. (The included allen key with your Greasecar kit is 1/8".)

Step Six: Gently remove the rubber flap from underneath the breather. This is simply a rubber flap. In normal situations, vacuum inside the tank will pull the flap inward, letting air flow through the 4 small holes in the cap. This rubber flap can stick to the cap, preventing the tank from breathing properly. The 4 holes can clog as well, having the same effect.

Step Seven: Clean the cap. The rubber breather flap, and both halves of the cap can be cleaned using warm water and mild dish soap. Be careful using degreasers, as some can negatively affect the plastics and rubbers used in the cap. A paperclip can be used to help poke out the 4 small breather holes. Before reassembly, lubricate the center shaft and o-ring using a food-grade silicone lubricant. Once you have adequately cleaned the cap, reassemble the cap in the reverse order.

Pressure relief valve

Pressure relief valve in it's normal resting position

Pressure relief valve in it's relief position.

With the fuel cap now cleaned, it's a good time to check the pressure relief valve. The pressure relief valve is located on the top of your tank. It is a small brass fitting, that either mounted on the hatch plate, or the top of the tank itself.

We designed the pressure relief valve to let potentially dangerous pressure out of the tank (note: tank does need a small amount of pressure; the valve isn't designed to relieve all tank pressure.). To check functionality, you should be able to freely move the piston from the valve. If the piston does not move easily, the valve should be cleaned. The valve is easily removed using a wrench if it is installed directly on the tank, or it can be cleaned by removing the hatchplate if attached. The valve can also be cleaned topically while on the tank (though this will not clean the inside of the valve). Any degreaser should be able to soften deposits, and a scotchbrite pad or wire brush should remove any further deposits on the valve. Once the valve can move freely, it is operational.