Why multiple fuel filters?

[vetplus40]

I have been reading a few threads where folks talk about having multiple fuel filters and I am trying to learn why multiples would be needed. As near as I can tell, my 2014 3.0 liter Mercruiser MPI only has one combo spin on type fuel filter/separator on the engine. Do different types of engines need more that one filter? Just trying to learn. Thanks

 

[alldodge]

One 10 micron filter is all that is needed.

In the early years the fuel pump had a filter which were a stone type, then went to paper. The pump filters where not that great, but better then most. The carb also had a small filter behind the fuel line connection. Other times people would cut the steel line and install a see thru filter (bad thing to do).

 

[vetplus40]

I have contemplated installing(winter project) a new spin on with a clear bottom portion for visibility and a drain petcock. I'm not sure if I can get one that will attach to my OEM mounting assembly, or if a aftermarket will be required. Still researching.

Why was using a "see through" bad?

 

[alldodge]

clear bottom portion
Why was using a "see through" bad?

They are not USCG approved for inboards or I/O and are dangerous. If something happens insurance may deny claims

 

[Lou C]

They are for outboards or mounting outside the engine compartment. However, if you want a bigger capacity filter you can get the Racor style with a metal bowl that also has a drain plug on it. I tried one and the hassle of getting the bowl off the old filter made me go back to the standard Sierra or BRP filters I have been using for years. Plus with the bowl whether its metal or plastic there are additional points where it could leak (gasket between the filter and bowl, and the drain plug itself). The filter is bigger and the bowl can hold quite a bit more water. I'd use the standard filters and dump it out into a mason jar at the end of the season. If it looks clear with no layer of water on the bottom, then you got all the filtering you need. Here's mine from the Sierra filter:

 

[Bondo]

I have contemplated installing(winter project) a new spin on with a clear bottom portion for visibility and a drain petcock. I'm not sure if I can get one that will attach to my OEM mounting assembly, or if a aftermarket will be required. Still researching.

Why was using a "see through" bad?

Ayuh,..... You've already got the best fuel filter there now,....

Just keep a spare on-board, 'n change it often, in these ethanol days,......

Once a year may, or more likely not be often enough,.....

I buy mine at my local Napa,..... # 3225,.... yer's is probably the same one,..... fits every Merc I've ever looked at,....
# 3226 is a shorter version of the same,.....

 

[vetplus40]

They are not USCG approved for inboards or I/O and are dangerous. If something happens insurance may deny claims

Good to know. I saw a pic of one on another site that had a little section on the bottom of the canister that was clear and had a petcock as well. Looked like a cool design. That said, I certainly don't need any potential insurance issues.

 

[vetplus40]

Ayuh,..... You've already got the best fuel filter there now,....

Just keep a spare on-board, 'n change it often, in these ethanol days,......

Once a year may, or more likely not be often enough,.....

I buy mine at my local Napa,..... # 3225,.... yer's is probably the same one,..... fits every Merc I've ever looked at,....
# 3226 is a shorter version of the same,.....

Mine takes an oddball filter(odd pipe fitting size) than I have only found at a Merc dealer. That said, the ethanol reference is a good point. I may need to start running less E10 fuel and more 100%.

 

[jimmbo]

If your boat blows up, and you’re on it, you may not be around to worry about ‘Insurance Issues’

 

[vetplus40]

If your boat blows up, and you’re on it, you may not be around to worry about ‘Insurance Issues’

Very true.