93 940 turbo

I have somewhat narrowed a problem down to either the fuel pump relay or the in-tank pump. I recently replaced the main pump and filter because it cut out a couple of times when tank got under 1/8. On a long drive it also stalled all together with over half a tank. I was able to start it 15 min later. Also, the cold start takes 3 or 4 cranks until the engine gets fuel. It was also whining louder than I thought it should. I replaced it, but still same problems and whining. I can here it pump just prior to starting, so I think the problem is in the other pump.

I have checked the faq page, but am still puzzled. There is mention of a fuel pump relay and a fuel injection relay (radio supression relay).Does the fuel pump relay control both pumps? If so, if its bad, wouldn't both pumps fail? What is the fuel injector relay's function?

I'm just looking for the best way to diagnose this. Some say listen for the pump running. Another said to pop the top of one of the relays and manually switch it on, but I'm confused as to which relay he's talking about.