Dropped RPMS

I fear it's another epidemic, contagious poor thoughts beyond factory specs to about every engine builder.
It will never be found in any factory manual explaining a fine filter first.
Even here in the swamps, at the stills, we understand course filters first.

I did find that DDC secondary cartridge (filters that go into the metal housing) factory spec; 22 mic.
The finest factory secondary (spin on) filter is around 10 mic.

Old Detroits flow lots of fuel.
Old Detroits can near burn anything other than water.
High performance 6-71 would luv great fuel but what ever you are burning, it needs a lot of it flowing.

But I have been drawn into a side topic and digressed.

Please check the blower bypass hoses and install a pressure gauge on the last filter output rite before the engine.

That's not to bad but a great start.
Send a pic of the media (filter).

I use Paint to quickly downsize photos to less than 650 pix on my desktop.

Have you been running bio-cide to keep fuel clean? Once it gets algee may need to have fuel and tanks cleaned?

Why am I confused?

By the way; 10 mic filters would be crushed in by now.

I have the same problems with swampwater,
rum,
bourbon,
vodka,
diesel..

If my Detroits can burn it, I can drink it.

Modern, super high pressure, super fine injector tips, common rail pumps, super fast computer controlled injector valve require super finely clean fuel.
Yes, Mfg's are requiring finer filtering solutions.
None are recommending a change in filter schedules with finer first.
AND, Detroit's do not require these supper fine and expensive filter plans.

What I hope Skippy J is recommending with finer filter first is a temporary path until your ship's fuel and tanks are clean again.
It might be convenient to just change the first filter knowing it will be trashed quickly.

13 years ago I learned about snake oils. This is my aft fuel tank pick-up after my first use of these products.



If you have a dirty tank, get it cleaned and fuel polished by a real shop.

On my 12V71TIs, Detroit spec'd 30 mic and 16 mic. Always ran great.
I added a middle filter that was between 17 & 20 mic with a water bowl also.
Funny that that second water bowl was collecting water (Racor stopped using real fish oil).
Still ran great.
Then like a Stuff For Brains, I installed 4-5 mic (black filter) as a final secondary. Lost 300 RPM off the top.
Going back to the factory 16 mic this weekend.


Why I bring all this up? I think your secondary is rated around 20 mic.
Your cannon bore injectors are going to starve during your cleaning process running 10 mic primary filters.

Then you have vacuum and pressure gauges ready to be installed.
Without them we are all just guessing.

The 43 Post aft tank will siphon/gravity feed to the forward tank if the shutoff vales at both aft tank and fwd tank ends of the fuel transfer line are open, the aft tank has more fuel in it than the forward tank (higher physical fuel level) "and" the line/aft pickup already has fuel in it from running the transfer previously. I always keep the fwd tank transfer valve shut unless activly using the transfer pump (easier one to get to) so I know how much fuel each tank will take. I usually keep 100 gallons more in the aft tank as the boat seems to ride better that way.