Is there a relay switch on 1998 Chevy blazer fuel pump?

No, the 1998 Chevy Blazer does not typically have a separate relay switch specifically for the fuel pump in the same way some older vehicles did. The fuel pump is controlled by the PCM (Powertrain Control Module) which uses the relay internally. The PCM receives signals from various sensors and determines when to activate the fuel pump circuit. While there's a relay involved in the process, it's integrated into the vehicle's overall electrical system and not a stand-alone component easily accessible for replacement like older designs. If you're having fuel pump issues, it's best to diagnose the problem with a scan tool to check for fault codes from the PCM.