Fuel pump issues - how to diagnose?
 

Driving home yesterday, came to a stop at a red light and a LOUD buzzing started to come from the front of the car.

I immediately thought it was the brake booster running, which was a problem when I first got the car - it would get stuck on. Fearing that it would burn out, I quickly pulled off the road to take a look.

Opened the trunk. No noise/movement from the brake booster motor. Verified it was not the oil cooler fan. Noise very clearly coming from fuel tank / fuse box area.

Thought it might be vent servos or fans, so played around with those a bit - nothing. Decided it was probably fuel pump noise, so I quickly came home. Took a look around rennlist and it seems fuel pump issues are reasonably common.

So the question now - what are my steps to diagnose that this is a fuel pump issue, and not the fuel pressure regulator, bad filter, etc..?

Car has been occasionally a bit harder to start lately, taking an extra crank or two. Since the buzzing has started, the car starts IMMEDIATELY.
Fuel filter was recently replaced.
Seems to run fine, even at high rpm - no power loss issues

If you jumper the dme relay so that just the pump runs you can turn on the pump and let it run without anything else running . If the pump sounds bad when it alone is running , then you need to find another pump soon .

Jumber instructions here:

http://www.adrianstreather.com/docs/...%20&%20388.pdf

Any FI service kit will have the gage and fittings to connect to the fuel rail and check the pressure and flow rate. If nothing else, that would let the pump flush out anything that may be causing the buzz.