300r External Fuel water separator?

[zyphyon]

3B098123
2021 300r

So I've had my boat for about a year and I've come to a point where I was going to change out my external Fuel water separator (sierra 18-7945), however I have read here that I do not need the external if I have the under the cowl fuel filter (8m176313) is this accurate? If so what are my options? I am thinking of just removing the external fuel water separator rather than bypassing the one on the outboard.

I assume that if what I have read is accurate, then I have been running the engine in a lean state, would I see any performance changes by removing that extra filter?
TIA

[Capt James]

I am running both filters. But the external Mercury one wouldn't fit, so I have a traditional spin on external filter and the mercury internal filter. I doubt you'd see any fuel starvation issues running 2 filters or performance issues.

[EuropeanAM]

You should have only ONE filter on these engines. When an external filter kit (should be equipped with Water in Fuel Feature) is installed, a bypass fitting should be installed on the engine.

[zyphyon]

Thanks I’ll go head and remove the external one as it has no sensor or anything just a screw on filter

[21xTriton05]

Thanks I’ll go head and remove the external one as it has no sensor or anything just a screw on filter

EVERY saltwater rig down by me has an external 10 micron RACOR or similar, and I've never had an issue with fuel delivery.

I have one on my Triton and never had issues either. NO, it won't void warranty either

[EuropeanAM]

EVERY saltwater rig down by me has an external 10 micron RACOR or similar, and I've never had an issue with fuel delivery.

I have one on my Triton and never had issues either. NO, it won't void warranty either

Perfectly acceptable- as long as the engine filter bypass is installed.

You're correct that it won't "Void the Warranty" (as there is no such thing). IF the engine fuel supply is restricted, any costs related to that (or damage due to running lean) is not covered under Warranty (under warranty exclusions- could also potentially be viewed as improper installation).

Of course- keeping filters changed regularly (and fuel system CLEAN) would prevent virtually any problems related to it.

[velvetskilett]

That is odd to hear as I looked at at least 10 different bay boats over the last 4 months with v8 mercs and not one dealer said anything about needing a bypass as everyone had an external spin on type mounted in the rear compartments or bilge. Do you have the part number for the bypass or a picture of one?

[EuropeanAM]

8M0152433 is the bypass tube to replace the original (in-cowling) filter. If a dealer looks up the recommended filter kit for the V6/V8 product (in boat), this part is a component of that kit (as is a filter, hardware, fittings, and wiring for water-in-fuel warning).

It's also good to note that while a water separating filter is an excellent thing to have- leaving the ORIGINAL filter in place may considerably delay your warning that there is water present (as an in-boat filter may trap and store a fair amount before any gets to the engine filter that has the warning probe in it).

Shown in the V6/V8 Rigging and Accessories guide (which dealers should be using when rigging engines).

[21xTriton05]

The filter on the engine is so small it's almost a joke. (Itll hold about the volume of a coffee creamer cup). By the time the water alarm goes off, every engine I've serviced had a VST full of water and then you have to take apart the whole fuel system for cleaning. Because who doesn't try to restart an engine when you're miles from the ramp after it stalls...The point of a boat filter it to catch a considerable amount of water and you're "supposed" to check them before each use. The separators with the clear bowl and a drain valve are the way to go. Merc may reccomend a lot of stuff but I've never had fuel delivery issues or a four stroke run lean because of a Racor.

[EuropeanAM]

Rob- I agree with you on that one. However: If you're rigging a boat with a Racor, why not use one with the Water in Fuel feature, and take the extra ONE MINUTE to install the bypass elbow (which literally costs less than $5 currently)?

That engine-mounted filter is not a water separator- it's simply a filter that has a water-in-fuel warning. Filter works QUITE well as a filter (but would be hard-pressed to separate 3 ounces of water).

[zyphyon]

Don, since this keeps being brought up it has me second guessing my life choices about just using the under the cowl filter only.
I see you have posted the number for the bypass elbow, so my two part question is.
The filter I had was the sierra 18-7945 ( I kept the housing just incase) if I wanted to swap that filter to a racor with a drain could I just the same housing unit and just screw on the new racor and if so which racor should I go with? And question two is, how do I go about hooking up the "water in fuel feature" to the external filter once I bypass the under the cowling one?

Or would It be better to install the bypass elbow and the racor and not worry about the "water in fuel feature"?

[EuropeanAM]

I don't have cross references for Racor, as what I recommend is one of the kits that already HAS the water in fuel sensor in the filter, and comes with the harness to extend the connection from the engine to the new filter.

Parts Department can assist with selection of an appropriate kit for this purpose.