T&T: Fuel filter monitor - Vacuum gage vertical location

[BillEGates@aol.com]

> Cummins Owners: Just a note to let you know that my idea about putting 
> vacuum gauges on the engine between the engines lift pump and the engine mounted 
> fuel filter was a bad one. I lost the port vacuum gauge first after 9+ hours. 
> The Starboard went after 18+ hours. We only lost one gallon of fuel into the 
> engine hold each time, both spills were contained 100%. I suspect what 
> happened was that when backing down, the Boshe Fuel pump offloads and sends 
> pressure back into the incoming fuel line. This destroys the bellows inside of the 
> gauge and the fuel pours out.
> 
> From reading literature from Flowscan, they recommend "Fuel pulsation 
> dampers be installed in some installations" I have a feeling this is one of them.
> 
> So, don't do what I did. It sounded good but just didn't work. But, if I 
> would have installed shut off valves..... Maybe next year.
> 
> (Cummins Replys) Information for you on your fuel filter gauge....The lift 
> pump actually puts a slight positive pressure on the system so you should not 
> put a vacuum gauge in a pressurized system or you will get failures as you 
> described. Racor and Fleetguard both make vacuum gauges that I would install 
> on/around the Racor filtration system that I think you have on the bulkhead of 
> your 46 Maxum. I would not mount it next to the lift pump as it might see 
> spikes from the pumping action of the lift pump giving you an artificially high 
> reading. The fuel line from the pump to the Racor system will act as a buffer 
> to minimize the pumping action. Almost all of the time the Racors will plug 
> long before the engine mounted fuel filter so it is more important to know 
> when to change the Racor filters than the engine mounted one.
> 
> 
> What I did was to put in two vacuum gauges on each engine, I thought that by 
doing so I could see which filter, primary or secondary was getting clogged, 
nice idea, bad practice. The positive pressure from the fuel pump blew up the 
very small, very weak bellows inside of the gauge and allowed diesel to flow 
out, into the bilge. By the way I still have the ports blocked off with a plug, 
and have opted to "change both" when a problem arises. When doing so I "cut 
apart the filters," and have found the 30 micron Racor, is always plugged, the 
2-10 micron Fleetguard, mounted on the engine is only slightly dirty.

Captain James Clausen
MV Summer School



Date: Sat, 10 Feb 2007 21:22:06 EST
From: Trainman484848@aol.com
Subject: Re: T&T: Fuel filter monitor
To: trawlers-and-trawlering@lists.samurai.com
Message-ID: <d55.1de76e5.32ffd7ce@aol.com>
Content-Type: text/plain; charset="us-ascii"

A pressure gauge piped into the system between the secondary filter output
and the injection pump works to a degree. Your final filter has to be on the
pressure side of the delivery pump (most are) Unfortunately this method may 
not
give you early warning it all depends on the volume of the delivery pump and
the amount of fuel used and returned in normal operation. The two gauge 
system
(a gauge on the input and output side of the final filter) works a little
better but still has the same draw back.

In my opinion the best way to determine the condition of the fuel filters is
to go to the 2 micron primary then your vacuum gage will give you a good
indication of the condition of your filters. Of course there are strong 
opinions
about that just take a look in the archives.

Brian Palmetto FL