XR950 PRO Fuel Cap Not Tightening or Opening Properly

If you're having trouble with your XR950 PRO gas cap not tightening down or feeling stuck when you try to remove it, the issue might not be with the cap itself. This engine uses a ¼-turn bayonet-style fuel cap, which can feel different from the typical screw-on types.

Here’s a closer look at how it’s supposed to work and what might be going wrong if it's still not fitting right—even after a replacement.

How This Fuel Cap Works

The Briggs & Stratton XR950 PRO engine comes with a bayonet-style cap that:

• Has two locking tabs underneath.

• Seals with a gasket (rubber or cork).

• Inserts into matching slots in the fuel tank neck.

• Locks into place with a short twist — about a ¼ turn clockwise.

It does not screw on like a bottle cap. If it’s working right, you should feel a firm stop when it locks. To remove, turn it back ¼ turn counterclockwise and lift.

Common Problems (and What to Check)

Cap won't tighten down or feels loose:
This usually means the locking tabs aren’t dropping into the tank neck slots properly. Dirt, misalignment, or damage to the neck can prevent the cap from seating flush.

Cap won’t come off easily:
If you can’t lift the cap after turning it counterclockwise, the tabs may be catching under the lock ramps — or the tank neck might be damaged or deformed.

Still struggling after replacing the cap?
If the cap was replaced and it still won’t tighten or release properly, the threads or locking slots on the fuel tank neck are likely the culprit — not the cap.

Next Steps

If you've already tried reseating the cap, cleaning the area, and carefully aligning the tabs, and it's still not working, the tank itself may need inspection or replacement.