QuestionTed,
I have a 1993 Toyota T100, 3.0L, 4x2, with manual transmission that will not start (mileage 180,000). I've been having trouble starting it for quite some time now (about 18 months) and it's been acting like a fuel delivery problem. I had a leak from the outlet line of the tank, but didn't want to take the tank down to fix it, because I needed the vehicle and the expense. In the interim, I replaced the fuel filter, thinking it may have been plugged. This didn't really solve the problem, but it got me through to when I could drop the tank. When I tried to start it cold it was acting as if it wasn't getting any gas. The pump came on as normal, but it wouldn't fire. It would eventually start after a few tries of pressurizing the system. The truck would run fine after it started with no problems whatsoever. Anyway, I finally got to do the fuel tank and found the steel line out from the pump sending unit to be corroded (as I expected) and not able to hold full pressure (which is why it was leaking). I replaced the line and the pump and put the tank back in. When I try to start the vehicle now, it will not start. I'm not getting the pump to come on at all. I'm getting power to main EFI relay and to the circuit open relay, but not to the pump. When I jump the circuit open relay to get power to the pump, the pump comes on but the vehicle still won't start. I've checked most every major EFI circuit, including the ECM, volume airflow meter, circuit open relay, cold start injector and its time switch and the TPS. I have good spark and good fuel pressure at the fuel rail (though I don't know what the exact pressure is). I've replaced the volume air flow meter because I didn't feel good about it (considering the mileage of the vehicle and a few readings). My focus initially was on the ECM, but I decided to check other components first and come back to that (which is what I did). Most all of the ECM voltage and resistance readings look OK, except for the TPS which looks a little high for resistance (voltage OK). My questions are: with your experience with these systems should I be focusing in on the ECM? Will a bad or even slightly bad TPS prevent the vehicle from starting? If I decide to replace the ECM, must I use one from another 1993 T100, 3.0L, 4x2, with manual transmission or can I use another similar ECM? I certainly appreciate your advice with this. Thank you very much. John
AnswerSince there is pressure from the fuel pump to the fuel rail and there is spark the next step would be to check for injector pulse, remove one of the injector connectors and with the key on check for constant battery voltage to one side of the connector to ground, if there is voltage connect a testlight across the injector connector terminals, crank the engine over and let me know if the light flashes, if it does the pulse voltage is good, do this and then let me know.
