The other day I did a search on how to wire my FASS so that I am getting 12v to it. There was a post that said you can use the ASD (Auto Shut Down) relay for the hot and ground it at the frame. So now I have a hot wire from the ASD relay going straight to the FASS with it grounded to the frame next to the FASS. Hooked up the old way into the LP harness, I could not hear the pump at idle. Now that it is re-wired, I hear a loud "humm" from the pump.
My question is after doing this is should it have made the FASS louder? Other than it being louder, it seems to be running perfectly.

Thanks

 

The FASS company told me that the FASS was not designed to be run at reduced voltage. On the pump feed, the best that I have been able to pull off as to how it works is this. The hot wire of the harness turns off and on with the sequence for start and run. The ground wire from the harness sets the resistance to ground to give the low start voltage and the full run voltage. So the relay system that fires off the fuel harness give straight 12 volts on the hot side but using the ground from the PCM still cuts the voltage for start and run. The difference is that you are using full 12 volts that should be proper for the FASS system. It is getting full 12 volts at all times, hence the hum is different and louder.

 

what is the advantage to running FASS like this?? i would be interested in switching mine setup...

 

Depending on the system, the FASS with the voltage cut may not be able to pick up fuel and push it past the air. On 12 volts I don't have to fill the filters to pick up fuel. With the harness it is touch and go if you get air in the line. How to tell? Does your fuel pressure gage kick right up to full pressure or hang around three to five pounds untll the engine is running a few seconds?

 

when I turn the key it jumps to between 5 and 7 then falls to 0 as I wait for the 'wait to start' light.. crank the key and jumps right up to 15...

 

See mine is lower that way and a problem. With the grounded fass and 12 volts, it will jump to 15 and then drop to zero. The problem comes when trying to prime it, when you bump the starter without the engine running you get the reduced voltage, in my case it was about 3 pounds only and could not prime right. This is dependant on the PCM function. Grounding it cuts the PCM out of it. Just don't ground the hot wire...

 

hmmm... I've had no problems with mine so I guess I'll just leave it be..

 

Thanks for all the input. I figured that the new sound was due to the increased voltage but just wanted to make sure it was not hurting anything.

 

If you are powered by the relay system provided by FASS, you can cut the ground wire a few inches from the pump and solder a connector to it to ground it to the frame. Just tape the harness back up and you will have 12v power. Mine operates much better with the ground direct. Then the PCM only kicks the relay.

 

I made my own relay going off the ASD that you had mentioned in a previeous post. I do have it grounded to the frame by the pump.