The ST020 fuel cap is a vented filler cap for older 020 series chainsaw tanks. It has a black plastic shell with a ribbed grip, an orange center plate with a rectangular vent slot, an orange sealing ring inside and a T shaped wire tether on the outside that hooks over the tank rim so the cap does not get lost. Air moves in and out through the slot as the tank pressure changes, so the tank does not swell or pull in, the cap does not work loose, and the seal is not deformed by pressure. If fuel seeps around the tank seat or the cap pulls stiff, check the sealing ring and the vent slot first; if the grip ring cracks or the wire bends, replace the whole cap. This cap is made for the ST020 tank; the 021, 023, 024, 025 and 026 are similar models from the same generation, so compare the old cap size and the tank seat, or send a photo to confirm.

 FAQ 

Q1: What does the slot in the ST020 fuel cap do?

It vents the tank. Air moves in and out as the fuel warms and cools, so the tank does not pressurize and the seal does not flatten.

Q2: What is the wire handle for?

The T shaped wire is a tether. Hook it over the tank rim while refueling so the cap stays with the machine and does not fall or get lost.

Q3: Which chainsaws does it fit?

It is made for the ST020 tank. The 021, 023, 024, 025 and 026 from the same generation are similar, but not guaranteed to fit, so compare the old cap or send a photo before ordering.