1998 Ford F-150 - smoke test question

where is the best place to hook into do a smoke test on my truck

Look on an EVAP hose that has a service port.


IF (and that is a BIG IF,) your 98 F-150 is anything like a 99 Ranger, it is on the drivers side- just above the front fender in front of the master cylinder. Look for the service port like in Tester’s pic.