High pitch noise (fuel pump) & dead gas gauge.
 

Just bought a '99 Blazer. Is it normal to hear the fuel pump running as a constant, high pitch noise? It's pretty loud and I don't ever remember having a vehicle which has had a loud pump like that. Also, the gas gauge no longer works (shows 3/4 or full tank constantly). I'm assuming the connector is shot but I'm wondering if the issues are related. The Blazer runs and idles fine (apart from 150k on factory plugs which will be gone soon lol).

I hooked a cheap pressure tester up to the schrader valve. The pressure starts at 61, clicks to 51, and then drops to zero within 4-5 seconds. The Blazer runs fine but as I mentioned, the gas gauge isn't working and I hear the pump on 24/7 while it's running (seemingly louder then I would expect it to).

The pumps are known for being loud and the fuel sending units are known for crapping out. Some have said their pump got louder just before it quit but mines been screaming at me for a few years now and I've got over 180,000 miles on it. I'll start to worry when I don't hear it.

Oh, and my gas guage hasn't worked for probably 5 years now. I just go by the trip odometer to know when to fill up.

This is a very common problem... the only way to fix it is to replace the whole fuel pump/gauge assembly unit that is in the tank. If you do replace it, don't buy a cheap one either, go for the AC Delco unit.

Ok. I wasn't sure. It's pretty loud though. With the gas gauge not working I'm thinking the top terminals are shot. I've got 153k on it and I'd rather not spend $400 on a pump right now (nuts).

Key on, engine off, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for 3 to 5 minutes after the pump shuts off. Excessive drop, like yours has, indicates a leak somewhere. If there are no external fuel leaks, the pump must be isolated from the rest of the system just after it pressurizes the system to determine if the leak is in the plenum or in the fuel tank.

Well, I examined the pressure gauge and I regret buying a cheap-o. Gas was leaking at the schrader valve AND at the gauge. When the vehicle was running, the needle was dancing a bit and leaking enough to be an issue.

I have no starting or running issues. I would imagine that if my pressure was dropping to 0 that I would have difficulty starting. I'll be buying a newer gauge soon. Any good ones out there?