I have a case where I am trying to troubelshoot a 1991 toyota 4runner with the 3.0 vs. The truck refuses to start.

Here is what I checked.

After listening to the engine cycle on all four cylinders during the start sequence, it sounds like all cylinder pressures were perfectly ballanced. alos, the engine start rpm sounded normal. Can see a little bounce on the rpm gage while in start mode.

Checked the timming. hand turned the harmonic to 0 TDC and opened up distributor to check rotor is pointing at #1 cylinder pin. It was. So that was good.

Checked the fuses to the ECM,IGN EFI and Open circuit relay. Good.

Checked the fuel flow to injecor rail. Cracked open the banjo bolt, cranked the engine and got fuel squirting out. Checked the return line going back to tank. Got no fuel return to the tank from the fuel pressure regular with or without vacume applied to fuel pressure regulator.

Checked spark on ignition coil. Recived good spark on the secondary circuit with about 1/4 inch above the gound of the fender.

Engine shows no hint at wanting to start. It did how ever, in one cycle tried but that was on one piston with a slight bump in starting rpm.

What bothers me is no return fuel is comming out of the fuel pressure regulator. While I have tested these on other makes and models over the years, that was only in a running vehicle. Not a no start. So I could be wasting my time in this case.

Checked the white/red and other wire comming out of ECU to injector banks with my digital meter for pulse Got a pulse on my meter for both banks at about 8 volts.

Whats left to check?

Invest in a set of those light up thingies they have at the parts places, you click em onto the plugs, and put the wires on the tool tops. they flash if you got spark. Cool things.