95 Volvo with m11 motor, truck won't start without ether.

You need to check for air in fuel and restriction first. Get a clear line between your pump inlet and tank and look for milky appearance or a lot of bubbles. Can also put a hose on the return side and run into a bucket of fuel and look for excessive bubbles in the bucket. Restriction gage at the pump inlet, 0 to -30 in is best to use. If a lot of restriction is found keep plumbing the gauge back toward the tank till you find it.

If no gauges run out of a bucket and see if it starts.

Also need to check fuel pressure at the fuel pump. There should be a compucheck fitting at the inlet of the gear pump. You should have 25 psi in under 6 seconds. If the gauge moves very slowly or takes longer than 6 seconds to build pressure the pressure regulator is stuck.