Fuel Pump Roulette

[fork]

I have an Aeromotive 340 fuel pump installed with a separate relay for power. Please see the schematic below to see how I have it wired. I installed the new pump a few months ahead of installing a supercharger.

The day I put it the new pump in, the car would not start as quickly as it did with the original pump. With the original pump, I would press the start button and the engine would fire up immediately. With the new pump, the engine would turnover for an extra second or two before starting.

After I installed the supercharger, I would also sometimes hear the pump prime and sometimes it wouldn't prime. If it did prime, the engine would crank for a second or two and start. If it didn't prime, the engine would crank and crank and would sputter for another four or five seconds and then finally start.

This morning I turned the car on and I didn't hear the fuel pump prime and the engine just kept cranking. Tried it three times and no luck. I tested the relay I installed and it seemed to work fine. I thought the fuel pump was bad. With my relay installed, I am briefly getting 12V to the pump for about a half a second after I hit the start button but then it goes down to 0V. However, the pump does not prime in that time that it is getting 12V.

Before I went to go pull the fuel pump out, I reconnected the original fuel pump power wires back together. The fuel pump primed and the engine started just as quickly as it had with the original pump. I tried it again and the pump primed and started immediately again.

Does anyone know when the ECU sends power to the fuel pump to prime? Is it supposed to happen every time you start the engine? Is there any reason why the ECU pump relay would not provide power when it is connected to my relay (how would it even know)?

Last question: The Stillen supercharger instructions simply tell you to swap out the OEM pump with the one provided by Stillen (I don't know the size they provide) but they do not say anything about adding a new relay or heavier gauge wire. My multimeter shows 11A draw to the Aeromotive fuel pump. The circuit is protected by a 15A fuse. Has anyone driven around with a larger pump on the original wire?