Yamaha "F" filter question

[99yam40]

big question would be what size partials does the electric pump create?
what are the most abundant size the 40m F filter catches ?
and how much of what size gets thru to the injectors and gets caught in those screens?
Would going to a 32 m solve a problem with the injector screens plugging up quicker with the brush dust?

maybe Yamaha engineers found the answers to these questions and made the decision to change the F filter to 32m

[pstephens46]

big question would be what size partials does the electric pump create?
what are the most abundant size the 40m F filter catches ?
and how much of what size gets thru to the injectors and gets caught in those screens?
Would going to a 32 m solve a problem with the injector screens plugging up quicker with the brush dust?

maybe Yamaha engineers found the answers to these questions and made the decision to change the F filter to 32m

Why not make the damn thing serviceable?

[99yam40]

well, then they could not sell as many filters

[pstephens46]

well, then they could not sell as many filters

They would sell more if they put it on the schedule.

[99yam40]

They would sell more if they put it on the schedule.

very true, they could just put it in to replace after so many hours.
but if they made them serviceable, people would try cleaning them and end up messing up and letting a bunch of crud into places it should not go to

[pstephens46]

very true, they could just put it in to replace after so many hours.
but if they made them serviceable, people would try cleaning them and end up messing up and letting a bunch of crud into places it should not go to

Just to argue my good man......hp filter is serviceable..

[marchmadness]

So if there is no maintenance schedule for this so replace when it clogs up. I guess if it passes air it’s okay

[99yam40]

Just to argue my good man......hp filter is serviceable..

which one are you calling the HP filter, and what is its micron size?

as you can tell I am not up on your motor and all of its filters

[pstephens46]

So if there is no maintenance schedule for this so replace when it clogs up. I guess if it passes air it’s okay

Passes air? Ask Roscoe what his wife’s reaction might be. Air bad. Gas good. What in the world?

[oldmako69]

The F filter is an idiotically overpriced piece of plastic with a screen. It has been strategically placed to make its replacement about as much of a pain in the a$$ as possible.

My opinion only....the alcohol in e10 eats the liner of the fuel hoses downstream of the VST and this liner sloughs off and winds up as tiny bits of rubber in the fuel recirculation system, from the injectors and back to the VST HP screen and everywhere in between. Meanwhile, moisture present in the fuel rusts the internal metallic components of the HP pump in the VST. Those tiny bits clog injectors and create misfiring cylinders. Axe me how I know.

So, there are two things at work which will eventually ruin your day on the water, tiny metal bits of metal from the HP pump, and tiny rubber bits from the fuel line. The F Filter ought to catch both, but in my experience catches neither.

I would LOVE to replace mine with a glass "see-through" filter but I have been unable to find one designed to handle pressure. Most of the glass filters you see on small engines/motorcycles are on the feed or suction side and will not handle pressure. At least, that's the way my mind thinks when wrenching on these motors. I don't want to experiment with high-pressure fuel shooting out of a ruptured fitting under an engine nacelle while offshore.

If anyone has a suitable fuel filter that will handle pressurized fuel, please post it.

[fairdeal]

So, there are two things at work which will eventually ruin your day on the water, tiny metal bits of metal from the HP pump, and tiny rubber bits from the fuel line. The F Filter ought to catch both, but in my experience catches neither.

well, the F Filter doesn't see any 'recirculating' fuel -
just the one pass of fuel as it enters the VST through the float/needle valve.

It can see some pressure -
maybe up to ~14 psi if the 'relief valve' is working correctly.

The 'recirculation' via the fuel rail/pressure regulator/cooler
is 'filtered' only by the HP pump inlet screen

and anyone would agree that the surface area, and pore size,
of the HP pump screen used on the early F115 / F225
was a bizarre design selection:

much, much smaller and coarser
than was used on any engine before (EFI 2-strokes)
or after (F250, F150 et al)

[99yam40]

well that throws out carbon dust from the pump getting in the F filter and the rust.
so it only catches things getting into the fuel system after the main fuel filters or what is ripped loose from the inside of the fuel lines

[oldmako69]

[QUOTE=fairdeal;n214355]

well, the F Filter doesn't see any 'recirculating' fuel -
just the one pass of fuel as it enters the VST through the float/needle valve.

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You're right of course, my bad. I don't wrench on my boat all winter since I don't run it much and had forgotten the exact plumbing.

Regarding this filter, I have pulled and replaced them on each engine. Both were clean. Frankly, I don't see what good they do other than facilitate the 90 degree turn split in the line. The F and the first stage engine filters are never dirty on my engines, given that they are just a few feet from the Racors. The dirt catchers are the Racor and the HP pump screen.

But getting back to what I said earlier, I have had my HP pump screen fully clogged with a fine black mess that I can only assume is rubber from inside the fuel lines, given that the first stage engine filter is clean as a whistle. I cleaned it with carb cleaner (no sense in replacing a 40 dollar screen) and buttoned the engine all back up. Unfortunately, I was then greeted with a steady misfire from one cylinder. I presumed that to be a clogged injector given the crap in the screen. So I tore it all down again and replaced the injectors. What a pain in the ass those days were. First, the engine started running like crap and ruined a nice day on the water. Then, toss it on the trailer, tear it down to the VST, clean it and put it all back together. Relaunch the boat, find the NEW problem, recover the boat, tear it down and order a set of injectors, replace, relaunch etc. After that episode, I put about 40 hours of perfect run time on the engines, yet now that same engine won't run at speed. It will start and idle but starves for fuel at higher power settings. There are valid reasons that people sell boats.

I am making the assumption that the injector was clogged with a very tiny bit of that black rubber or rust from inside the HP pump that was puked into the fuel lines to the injectors.

[marchmadness]

So in old makos case replacing the F filter might have kept the vst from being clogged and injectors. I would think then changing to the 32 micron screen would be better

[99yam40]

not if the debris did not come from the tank side of the F filter.
fairdeal said the F filter is not in the re-circulation path. so no way to catch brush dust or rust from pump in the VST