FASS noise, low voltage

[STSchroeder]

I can't find the post that talked about low voltage and FASS noise. When truck is started and grid heater cycles the FASS gets real noisey, then cycles off very little noise. I have checked the fuse and cleaned all connections. Is the wire on the FASS too small for the distance run? Is the FASS drawing too much amps? Everything works fine after grid heater is through doing it's thing. OPINIONS?

Steve

 

[tractorface]

I would not panic but bigger wire is nice

I upgraded my FASS harness to 14 gauge wiring, I believe the new FASS harness has 14 gauge wiring as well. I am of the opinion that the standard 18 gauge wiring is too small. 12 volts does not "travel well". I could back this up with some simple calculations using ohm's law but not sure that would help and don't care to spend the time. As for noise it is directly related to tank restriction from my minimal expierience. Trucks like mine with just a 1/2" pickup in the tank and no OEM tank module have really quiet FASS's on them. There is no way you can tell mine is running when the truck is running. You really have to listen when you bump the key unless you just changed the filter. With that said I can see where the voltage drop would cause the pump to "struggle" with its task and be a little louder. My wiring change was brought on by the badly corroded fuse before the FASS. I was simply going to eliminate it from the harness when I saw how bad the wire looked I decided to make the change. Bigger wire = less resistance which is a good thing here. Just to give you an idea the DC current resistance at 75 degree C for 18 gauge wire is about 8. 45 ohms per thousand feet while 14 gauge wire is 3. 26 ohms per thousand feet. Not sure what the current draw is on the FASS but cutting the wires resistance by over 50% can't hurt. FWIW 14 gauge wire is the largest that the OEM Deutsch connectors on this circuit will accomodate. The crimper is not cheap, Any CAT Generator technician should have a set on his truck. Many of the connectors on the CATs are Deutsch brand. Hope this helps.

 

[STSchroeder]

Fass

Thanks the for input. When I put the FASS on I pulled the tank and bypassed the factory pick up with 1/2" pipe and hose all the way to FASS. I could see there was no way through the factory pickup. I'll try the 14 guage or try FASS for updated harness.