Anyone know what the name of the part that pushes the button to starts the car when you push the clutch in a 1990 Toyota pickup?

Seems like the cable is broken (only a few strands left & stretched). Remove the cable & check it out. Probably needs to be replaced.

PUT A NEW MASTER CYLINDER AND BRAKE BOOSTER ON 1990 TOYOTA PICKUP AND BLEED BRAKE AND YOU HAVE TO PUSH ALL THE WAY TO FLOOR TO STOP WHAT COULD BE MY PROBLEM?

your transmission and spark plugs

There will be a switch on the clutch pedal bar under the dash somewhere. When you push in the clutch the pedal touches the switch and completes the circuit. It may be out of adjustment, or just worn out. You can either replace it, or remove it, and pigtail the wires together. Although, if you do that, be aware that it will start in gear, clutch out, and could be a safety issue.

Push the clutch down while you are looking at the switch, it is right at the top of the clutch pedal. My bet is that there is a gap and the pedal is not engaging the switch. The sheet metal on the fire wall probably gave way. Check it out, then you can reinforce the firewall that the clutch safety switch is mounted on. Good luck. I just had this happen tonight. Much quicker then tracing wires.

Check the setting of the clutch safety switch on your clutch pedal.

There is an adjustment for the clutch pedal under the dash where the push rod goes thru the firewall. There is only aprx. 1/2" of adjustment so be careful when making an adjustment, if your clutch is slipping then you need to shorten the throw of the push rod.

check the brake switch, you might need a wiring diagram to see exactly how the wiring is, but that is a possibility or it could aslo be the flasher

CLOSE BLEEDER SCREW AND PULL PEDAL BACK UP MANUALLY. CONTINUE BLEEDING THIS IS COMMON AS YOU LET THE PRESSURE OFF AND CYLINDER WONT PUSH BACK UP.ONCE YOU GET BLED SHOULD WORK FINE

sound like a vacume leak get a can of carb cleaner . with the engine idling spray around the intake and base gaskets if the idle changes you found your leak cure the leak cure your problem