I can't find the fuel pump relay in a 1993 Toyota previa.

When you turn the key, the fuel pump pressurizes the system and then waits until the engine is running. 3 Seconds is about right.

The Fuel Pump Relay is shown in the link.

https://www.google.com/search?q=1993+toyota+tercel+fuel+pump+relay+location

https://fuseandrelay.com/toyota/tercel-corsa.html

....

Normally fuse blows off if more current passes through it than what it is designed for.

Probably it is worth checking what original fuel pump fuse amps requirements and have the same installed.

Also check the relay if there is a relay set for the fuel pump.

Good luck

The short will be in the fuel pump.

CHANGE THE PRESSURE REGULATOR TO THE FUEL PUMP,AT THE HARNESS UNDER THE HOOD NEXT TO THE BATTERY

FUELPUMP WAS REPLACED AND STILL WONt PRESSUREIZE

try running an injector cleaner thru the system.
you may have a dripy injector.

Fuel pump relay is in the engine compartment left side fuse block

I would change fuel filter any way only £6 delivered on ebay then i would start looking at glow plugs and relays first check to make sure glow plugs are getting a live feed bad side glow plugs are located under drivers seat side of engine so not easy to get at unless you remove seat carpet and engine covers

Electric. All fuel injected vehicle must have an electric pump.