car sometimes won’t start. replaced fuel pump. still the same. I know it won’t start until I hear the fuel pump kick on. So If i don’t hear it I have to turn the switch off and on until I hear the fuel pump kick on. Sometimes it might be 10-20 minutes until it goes. Been doing this for years and nobody can figure out why. One mechanic said throttle body sensor and another said I need another computer. One more mechanic said I need to take the car to a dealer to have the computer rebooted. Starting to not start more frequently. Any ideas? Car is a 1997.
Check the wiring to the fuel pump relay, if good, swap the fuel pump relay with another one (usually there are at least 2-3 relays of the same type you can swap around to test) if starts, replace relay. Also could be a sticking fuel pressure sensor, should be on the injector rack, fuel is under high pressure even when vehicle is turned off, should be tested & replaced by professionals.
It is a matter of sherlock holmes, trace the voltage when in failure mode to find the weak link. Rule 1 is to clean all connections. Sounds like a bad ignition switch could be a source of the problem.
I have seen people run HOT wire to fuel pump with a switch that you turn on when you start it and turn it off when you stop.