Thanks for the quick response, Alex. And thanks for correcting me on the Pin #'s. Indeed, 86 is connected to the ECM. I just turned the key on for the first time today. The fuel gauge worked, but it did not prime so I shut it off immediately to do some probing. I had enough ground at Pin 85 to light my test light; however, there was a voltage difference. From the positive battery terminal to Pin 85 measured 10.9 V. The battery from terminal to terminal measured 12.2 V. Everywhere else I've compared voltage has been the same as the battery. That seems a little suspicious. I turned the key to On again and after about 3 or 4 seconds, the pump spontaneously primed. After that, it would prime immediately every time I turned it on just like it has done before. I measured the Pin 85 voltage again to see if it was different - still 10.9 V. I could not locate G105. Could you tell where it is in relation to some of the components?
Also, I wanted to mention that while I have not confirmed it, I suspect that when this issue is occurring that the fuel injectors are not being signaled as well, which I think may explain why using a jumper at the relay operates the pump but does not work to get the truck started.
Thursday, July 25th, 2019 AT 4:02 PM