On 2007-08-12 08:20:15 -0400, "Roger Long" said:
In 38 years around boats with auxilliary engines, I've never actually
experienced a clogged fuel filter so I'm curious what the first signs are,
at least for slow build up as opposed to the fuel line suddenly sucking up a
mess that's been kicking around in the bottom of the tank.
I would expect that slowly developing problems would first show up at
maximum RPM and fuel flow and that the engine would continue to run properly
for a time at lower power. If I make it a practice to bring my engine up to
full RPM at least once during every run, I should first see a failure to
reach the usual number, perhaps accompanied by some smoke due to the
injectors not getting enough fuel for the rack setting. Backing off to my
usual cruising fuel flow, which is about 60% of WOT, should give me plenty
of running time to get to a place where I can safely change the filter.
Next year, I'll put in a vacuum gauge but, in the meantime, will this
strategy work?
We had it happen once, just after we filled up the first time for the
season, about July. Seems there was lots of junk on the tank sides and
we were using the finest Racor filters. Engine started losing revs; got
a few seconds if I advanced the throttle, but then it died.
Changed the filter and cleaned out what I could, but the second clogged
in a couple of minutes' full power.
Not having a third filter (then) I brushed off the filter, cleaned the
bowl, and tried at reduced throttle. We could pull maybe 2000 (out of
3600) but that was enough to limp along at 4-5 knots to a "must"
rendezvous about 50 nm away. After those hours, we found out that we
could pull full power, and the primary (on the engine) filter was still
clear. We now carry a "coarse" filter as a third backup.
Oh, and I'm sure you realize that a dirty prop can drop the revs
significantly, so do your high-speed tests after you've powered for a
bit after a week or two away.
--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
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