Aloha everyone.
So I switched out the fuel pump relay. Didn't seem to help. I took the old fuel pump relay and put it into the main fuel relay slot and left the new relay in the fuel pump relay to test the main relay. Results are inconclusive so far on that.
Haven't gone out and bought a fuel preasure tester yet. I tried using the tire gauge and just got a nice spray of gasoline all over, so I might have to just spend the $50 for the real gauge.
One other idea that came to mind that I want to bounce off you all. Could I possibly have a bad Vehicle Speed Sensor? This is what it says in the service manual:
The vehicle speed sensor is located on the side of the Transfer box adjacent to the parking brake. The sensor provides road speed data to the ECM. The ECM in turn detects vehicle movement from the road speed input and ensures that idle air control mode is
disengaged. ***Should the vehicle speed sensor fail in service the ECM idle air control would become erratic.*** The sensor also provides road speed data to the
electric speedometer and cruise control ECU.
So if that could make the idle air control messed up, could that be my problem? Something else to note is that my cruise control also does not work. (never worried about the cc not working because I live on a small island.)
A second alternative to consider: the throttle position sensor. Again the service manual:
The throttle position sensor is mounted on the side of the plenum chamber inlet neck and is directly coupled to the throttle butterfly shaft. The throttle position sensor is a resistive device supplied with a voltage from the ECM. Movement of the accelerator pedal causes the throttle valve to open, thus rotating the wiper arm within the throttle position sensor which in turn varies the resistance in proportion to the valve position. The ECM lengthens
the injector open time when it detects a change in output voltage (rising) from the throttle position sensor. In addition the ECM will weaken the mixture when it
detects the throttle position sensor output voltage is decreasing under deceleration and will shorten the length of time the injectors are open. When the throttle is fully open, the ECM will detect the corresponding throttle position sensor voltage and will
apply full load enrichment. This is a fixed percentage and is independent of temperature. Full load enrichment is also achieved by adjusting the length of
the injector open time. When the throttle is closed, overrun fuel cut off or idle
speed control may be facilitated dependant on other inputs to the ECM.
The throttle position sensor is ’self adaptive’, which means that adjustment is not possible. It also means the throttle position sensor setting is not lost, for
example, when throttle stop wear occurs.
So if the throttle position sensor depends on resistance to function properly, could the copper wires that are exposed coming out of the TPS cause a change in resistance when exposed to heat and thus not allow the TPS to function properly? It looks like the rubber coating of the wires has become hard and brittle after 15 years.
Sorry for another long one and thanks a lot for your comments or ideas.
Eric