2007 Ion w/ 2.2 liter engine.

The gas gauge wasn't working, so I dropped the tank and replaced the fuel pump/fuel level assembly. The engine cranks over fine, but it won't start.

The 15 A fuse for the fuel pump is fine. I removed the fuel pump relay and shorted the two contacts in the fuse panel that go to the relay's contacts. The fuel pump kicks on, and the engine starts fine.

I replaced the relay. But that didn't fix the problem!

When I turn the key to the ON position, I can hear the fuel pump kick on for a few seconds, and then it turns off. But the car just won't start. Any ideas?

 

I just went out there again. I turned the key to the ON position, and the fuel pump kicks on for about 2 seconds. I push the schrader valve on the fuel rail. No fuel.

I override the relay, and allow the pump to stay on for 20 seconds. I push the schrader valve on the fuel rail. A tiny bit of fuel comes out.

So now I'm thinking it's not an electrical problem. It seems like there just isn't much fuel pressure.

Could the new pump be bad? Or maybe the fuel filter is clogged?

It's a Delphi FG0915 pump:

https://www.rockauto.com/en/moreinfo.php?pk=3977622

Update: I bypassed the relay again. Fuel pump stays on. Car starts and runs perfectly. I let it run for a couple minutes. Shut off car. Remove relay bypass. Reinstall new relay. Turn key to ON position. Pump comes on for a few seconds, then turns off. Engine cranks but won't start. It really seems like low fuel pressure. I wonder if the new pump is bad? I just placed an order for GM part number M100177. Which means I have to drop the tank again.

It acts as if pressure is bleeding off very quickly. Like there's no check valve in the fuel pump.

 

I wouldn't be surprised if the pump is bad. I've had numerous bad delphi pumps over the last few months. Delphi is the OEM for GM.