Fass Fuel System

Just like these guys calming 9mpg, what a crock of BS, then they tell you there doing this and that, like one guy, took his clutches out of his fan for better mileage, what a joke................

 

The Fass system doesn't replace the gear driven mechanical pump but aids it so it doesn't have to suck the fuel.
The Fass system only provides approx. 15-23 psi fuel pressure to the pump and removes small amounts of air out of the fuel system.
Factory oem only puts on the necessary pump. Some factorys do pump on the Davco filter system but it was out available for approx. 10 years before factorys started installing it as a primary fuel filter.

 

That's not a bad idea, I was assuming just the fass alone, I know if you have a lot of power, then yes I would have a pusher pump....

 

The oem mechanical pump can run as normal when not powering the fass system. I have my fass system on a switch and don't run it all the time, just during certain times like when fueling, climbing hills, and starting.

 

Now apply that retort to Davco.

FYI, my truck doesn't have one. Why didn't the factory put one on, if they're so great?

And my cousin's DD15 does have a factory installed Davco.

 

Every single item on a truck is an option, they bring in stock trucks built cheap so you will buy them. I worked at a dealership and owners would spent thousands of dollars on fancy stuff, to look cool to other drivers, but not a thing under the hood, or to help with aerodynamics.
Just a thought!

 

That is what FASS claimed several years back. In reality the FASS will not bypass when the "rubber" gets hung up. They had a problem with this occurring. You may be causing your pump to work harder to pull fuel thru the FASS. Why would you not run it all the time?

 

I go by a fuel pressure guage.
I do not run it all the time because I think there is alot of the time, it does very little if any good.
I wouldn't think it would cause the mech. pump to work harder since it already works against a releif valve but it very well could be. Now I'm gona have to get me another guage to check that out. Guages can tell so much more than we can feel.

 

You are so right - gauges and instruments are way more accurate than our brains. What I had in mind was the restriction on the suction side of the mechanical pump. Is it harder for mechanical pump to pull fuel to itself when the FASS is off and therefore a restriction? on the suction side or no difference. You would need to put a fuel filter restriction gauge between the FASS and the mechanical pump. You would also would need to be able to read the gauge when the truck is under a hard pull needing the maximum amount of fuel. I perhaps have overstated my thought. I just want to be clear. It will be interesting to see what does happen. Please keep us posted. I know for a fact that an Airdog is a significant restriction when it is not running. But they never advertised that it would bypass in the event of a failure.

 

On my last truck 8PN I had the fuel preporator airdog. I installed a compound gauge, vacuum/pressure, the gauge was installed between the airdog and the mechanical pump. With the switch on about 15 pounds pressure. With the switch off very little restriction like 2 inches vacuum. Ashcroft is who made the gauge. That being said this is what I put on my 6NZ. Racor 3150R with the 3238 10 micron filter 150GPH