I've got a FASS Platinum with only about 4,000 on it. With the weather turning colder here in PA, I've noticed the FASS seems to have gotten louder. Instead of a steady whine, I get the intermittent "whaa-whaa" sound too. As if the pump is struggling to pass fluid through. This pump is getting loud enough to hear over the motor with the windows closed.

I've noticed no loss in fuel pressure or performance.

Has anyone else had this problem? Is it normal for a pump to get a little louder over time?

 

no worries mine has done it for 5 years. its normal

 

Diesel fuel gets thicker and harder to pump as it gets colder.
Also sound travels better the colder it is.

 

Yep. It's probably cavitating. Are you one of the guys with a filter before the pump? What size are your inlet lines?

 

Yes, I have a NAPA Gold in-line filter between the tank and pump. I'm not sure of the line size since I didn't install it, a local diesel shop did.

I'm going to chaulk this up as normal at this point. We've had some 40-50* days and the pump is again back to it's whiney old self. There has been no sudden pressure drop or performance decrease.

I think what I'm hearing when it's cold, is sound waves coming up through
the bed and bed liner. Rail mounted pump under cold metal and plastic liner = strange noises.

 

Could be sound waves, I don't know anything about how that works.

There's guys on here that will argue with me, but here's how I see it:
The first place I'd be lookin' at is that filter, regardless off it's rated fuel flow. Rated fuel flow is at rated temperature. Diesel thickens as it cools (meanig it's harder to move - push or pull)and rated flow temperature is not 20*F and lower. Add that to the fact that fuel pumps push better than they can pull - especially electric ones.

You may not see a loss in performance or pressure but that does not mean the pump is operating correctly. Somewhere in your fuel system there is a valve that regulates pressure using excess fuel flow (return). The fuel pump flows much more fuel than the engine needs so you're PSI gauge won't register a difference until there is basically no return flow - pressure valve no longer has flow to regulate so the pressure drops. As far as performance, you can run full load at just a couple psi (at full load) so you won't notice anything there either till it's too late. In other words, your pump can have a pretty dramatic drop in fuel volume before you can detect it.
Now if you had an inline fow meter......

As long as you're fuel pressure is good, the only thing that's suffering (probably) is the electric pump itself. It really sounds like cavitation to me. The gears inside that pump will start to pit and it will wear out quicker than it was intended to.

Ever see an OEM system with a fuel filter before the pump? Nope. Just an inline strainer and sometimes not even that.

 

I figured that's where you were headed with that first post. I thought of this too. However, and this is the big one, FASS has a lifetime warrenty on their pumps. I bet big money that warrenty will be void if there isn't a pre-filter on the truck.

 

I won't argue with the warranty 'cept for one thought: define pre-filter.
I'd bet the fuel strainer that's good enough for Stanadyne, Bosch, CAV, Lucas and all the others is good enough for FASS... no?

 

....and there's a fuel strainer on the pick-up tube in the tank, right?

 

Exactly, so I'm thinkin' you're covered?