Minimum Voltage for Fuel Pump?

[WhalePirot]

I tapped the 12vdc IGN switched feed for my electric hydro boost pump. Often, both run immediately when I start the car. I have an intermitant no-start (no fuel pressure), even when the hydro boost doesn't kick on. I 'fixed' this before by replacing the FP relay. After a very short time, the problem is back. I wonder if the voltage drop when the Hydro kicks on, spikes the current thru the FP relay and began frying the new one.

OR, is there a minimum voltage for the FP to operate. I'd think, with such a strong cranking, that the FP had enough juice.

All I did to fix the no-start this time, was charge the battery. Previously, the engine cranked just fine, but would not start. ad

BTW, I am seeing a reluctant hot-start again.

Oh, the joys of a hot rod!

 

[redc4corvette]

All I know is the voltage is increased to the fuel pump by the computer as more fuel is needed at the engine.
You may have to run a seperate system for the other pump and kick the secondary pump on when you need it.
I think with two pumps on the same relay it will not handel the load and will burn out the relay or put an excessive load on the computer.

 

[WhalePirot]

I found that the car will start even with 8vdc. Turns out, a shop says the Optima battery is garbage; so quickly, too.

The ECM turns the fuel pump relay on/off with a 12vdc signal.