I know you said you have 8V at the pump but where are you taking the ground from on the meter? I have 20ft lead I use to ground straight to the battery and if the voltage comes out OK I check with the meter at the fuel pump ground. Trucks in particular have problems with bad grounds near the pump since they are often exposed to harsher environments.

Does it have a security system/light?

I worked on a Dakota that randomly would trip the security system and the fuel pump wouldn't fire up.

Not saying it's the problem but when I have a no start on anything newer than 1980 I start with the security light and see if it thinks it is stopping a theft. BMW's disable the ignition, some cars will disable the fuel pump. My wife's new compass disables the starter.