My Topeak Joe Blow bicycle air pump stopped pumping air. Repair took about 30 minutes. That includes the time I spent eating a sandwich for lunch.
When an air pump stops pumping air, it’s generally because the rubber o-ring attached to the end of the plunger has worn out. If you can get at that o-ring and find the correct replacement part, repair should be pretty easy. Given that quality floor pumps run $40 and up these days, a little time spent in repair might be worth the effort for you. Plus, you can have fun getting your hands a little dirty!
There’s not much to disassembly on my specific model: the Joe Blow Sprint. You just need a 1¼ inch wrench to loosen the handle and a 4 mm hex key to remove the base from the bottom of the barrel.
Once you unscrew the caps and bolts, use a little elbow grease to remove all of the parts. Work over a clean surface to ensure you don’t lose any tiny parts.
For my pump, the o-ring is likely a little worn, but the real problem was beach sand in the bottom of the barrel! I cleaned the grit from the barrel, plunger and from the check valve at the bottom of the pump barrel, and lightly greased the o-ring.
Regular automotive grease — including lithium grease — reduces the life of rubber and plastic parts. To ensure maximum life, you should use a silicone grease inside of air pumps. In real life, though, very few people actually use silicone grease in pumps.
If you need to replace the o-ring, some bike shops have air pump rebuild kits that include o-rings and other small, breakable parts such as springs and valves. You might also bring your old o-ring to the hardware store to find a match. Finally, you can purchase a rebuilt kit online for a little over $6 from Jenson USA.
Cheaper pumps may have the caps glued onto a plastic barrel. These are not easily repairable.