I was having the same problem last week with a new fuel pump,so I decided to check the relay and fuse,they were good so after climbing in the trunk with a test light,my problem was the ground wire for the pump that plugs in under the trunk area.
After stripping an inch or more of the insulation from the wire I could touch it to one of the pump cover plate studs with the engine running,and the pump would increase its speed.
I made a temporary fix by cutting the pump ground,soldering a lug on the end,and attaching it to the trunk floor after grinding the paint off.
There is a write up about rewiring the fuel pump,but I haven't tried that method yet. Maybe this fall when in-car temps are below 90.
After stripping an inch or more of the insulation from the wire I could touch it to one of the pump cover plate studs with the engine running,and the pump would increase its speed.
I made a temporary fix by cutting the pump ground,soldering a lug on the end,and attaching it to the trunk floor after grinding the paint off.
There is a write up about rewiring the fuel pump,but I haven't tried that method yet. Maybe this fall when in-car temps are below 90.