How many fuel filters do you have??

[CaptBobO]

Last year I bought a 2000 410 Sundancer that had the engines swapped out in 2005 with the Mercruiser 8.1S motors.
These motors have the Gen lll cool fuel filters but I noticed that I also have fuel/ water separators mounted on the bulkhead in the engine room.
Can anyone please tell me if you have both sets of filters for your engines?

Thank you

 

[Stee6043]

I've got four (4) total spin-on water separating fuel filters. Two on the bulkhead, two on the motors.

 

[paulswagelock]

Merc does not recommend external filters when equipped with cool fuel 3 modules. However, I have heard of several folks using that set up. Merc claims the extra restriction makes the pump overworked and fail earlier.

 

[CaptBobO]

Merc does not recommend external filters when equipped with cool fuel 3 modules. However, I have heard of several folks using that set up. Merc claims the extra restriction makes the pump overworked and fail earlier.

Yup!! That was exactly my thought. having too many filters might make the pump work harder than it has to.
I need to call Merc and see what they recommend for my engine.

 

[CaptBobO]

****UPDATE***
I emailed Mercruiser and asked them my question. Here is the direct response I just received. Looks like Ill be removing my additional inline filter:

The 496 engine with Gen III fuel cooler has a water separating cup within it and there is no need to add additional fuel water separator. We caution installers about adding too many filters as adding this, may increase the vacuum needed to draw fuel from fuel tank to the engines fuel pumps. We have a fuel vacuum spec of 2 in. Hg or less in all operating ranges. If more than 2 in. Hg vacuum is found, this may contribute to issues with vapor locking. This can also create performance issues as fuel could be starved from engine.

Bottom line is the filtration on this engine and water separating is adequate as designed and no need to add extra.

 

[CaptBobO]

After removing the auxiliary 10 micron fuel/water filter as recommended by Mercruiser, I tested the fuel pressure at the rail.
How does this look to you guys? Is this normal? It stays at 40 at idle, and if I give it a little throttle, it dips to 37 and back up to 40. Also, there is no load on the engine. Its just throttle. Thank you for you input!

 

[Espos4]

After removing the auxiliary 10 micron fuel/water filter as recommended by Mercruiser, I tested the fuel pressure at the rail.
How does this look to you guys? Is this normal? It stays at 40 at idle, and if I give it a little throttle, it dips to 37 and back up to 40. Also, there is no load on the engine. Its just throttle. Thank you for you input!

So far so good.
If you’ve got an extra set of hands, take it for a ride and record the fuel pressure under load. That’s the true test of the pumps and regulators ability to perform properly.

I realize that you didn’t report any drivability issues, just asking about the extra filters.

 

[CaptBobO]

So far so good.
If you’ve got an extra set of hands, take it for a ride and record the fuel pressure under load. That’s the true test of the pumps and regulators ability to perform properly.

I realize that you didn’t report any drivability issues, just asking about the extra filters.

Thank you. the drivability issue is:
Engines start fine.
Can drive around for an hour no problem.
While stern docking and going in an out of gear in short bursts, engine sputters and goes out. Ive changed out cool fuel filters, removed auxiliary filter and here is where I am now.
min thinking the engine was starving for fuel with two sets of filters. next on list if changing out spark plugs.
will take boat out tomorrow and test.