gas cap, fuel cap, the clicky thing where you pump money into

the gas cap matters much more than you’d think. If you install one of those aftermarket metal caps or a locking unit, neither are vented properly (even though they say they are). Without proper venting it can actually cause drivability issues related to fuel pressure. Both carbureted and fuel injected trucks rely on venting for proper fuel pressure, if either isn’t vented right, it can cause fuel starvation since it’s creating a vacuum trying to get the fuel from the tank to the intake.

also the wrong cap, missing cap or your 30+ year old one with a bad seal can allow dirt, water and small woodland creatures into the tank and create havoc with your system.

Buy it right. Genuine Toyota part