DIY GEN III Cool Fuel
 

I was changing fuel filters on my 6.2's and took some pictures. If some of you out there have not done this yet it will show how easy of a job it is. Literally takes 5 minutes per engine. I actually think the Mercury engineers had the customer in mind when designing this thing!:D

The cool fuel module is where they put the heat exchanger, fuel pump, filter, and water separator into one package. I believe the 496 engines are the same as my 6.2's. Only change the fuel filters on a cold engine. Mercury recommends that it be shut off for 12 hours, but that seems a bit extreme...

Pic1 - Exploded view of the generation III cool fuel module.

Pic2 - The module is on the front port side of the engine below the alternator.

Pic3 - First dicsonnect fuel pump from the engine wiring harness. Turn the ignition key and operate the starter for about 5 seconds to release any fuel pressure. The filter cap is held in place by three screws. The only tool you need for this job is a 10mm socket or wrench.

Pic4 - After loosening the three screws (they do not come out of the cap) pull up on the filter cap handle to unseat the o-ring. Let it sit in this position for a few seconds to allow the fuel to drain out of the filter cup.

Pic5 - This shows the filter/water separator assembly. Hold the filter cup and rotate the cap clockwise to remove the cap.

Pic6 - This is the filter cartridge. It seats on a post in the filter cup.

Pic7 - Filter removed from cup.

Pic8 - Here is all there is to the kit.

Pic9 - Had a little debri from the fuel tank, but no sign of water.

Pic10 - Wipe out the inside of the filter cup. The paper towel shows the residue that was in mine.

Pic11 - Don't be tempted to use a screwdriver or some other tool to remove the o-ring from the filter cap. You risk scratching the plastic sealing surface. Just dry the o-ring so it isn't slippery and grab it with your finger and thumb and pinch/slide it to expose some slack.

Pic12 - Grab the slack and pull it off.

Put on the new o-ring and put everthing back together. Slowly install the assembly back in the module to prevent spilling fuel. Tighten the three screws. The manual says 53 in-lbs (a little past snug). Start the engines and check for any leaks.

BTW, my Formula does not have a fuel shut-off valve and I had no problem with fuel draining into the module while working on this. If you have a shut-off valve, use it.

That's it!

there is also another filter below the cup that you are showing. it looks like a shallow round tray and you pull it out with needle nose pliers. they are not cheap. Jim

I saw that in there, like a strainer and thought it was permanent. Mine looked clean. Do they sell replacements or is it cleanable? Didn't see anything in the manual about it. Thanks!

usually you replace them. p.n. 35-892665

how much?

Good information. I agree that the secondary filter (35-892665) should be replaced also.

I learned this the hard way (snapped a bolt off in the module), clean the bolt threads and apply thread sealant before reinstalling the filter cap. Also, don't pull the filter out unless you have a new o-ring for the filter cap. The o-ring swells up slightly and may not reinstall properly.

Merc service bulletin on Gen III Cool-fuel diagnostics;

http://www.marinepartsman.com/Mercur...2004/EN_06.PDF

Gen 3 fuel filters
 

has any one found these parts somewhere where they don't cost an arm and a leg. Mercury sells a kit which has both the dic orin and paper cartrige but its about $65.00 for a set . I need two everytime

The best price I have found is on ebay through Shipyard Marine. They sell the filter set (cartridge 35-866171A01 and tray 35-892665) plus o-ring for $56. I ordered two sets and shipping was $7, so $119 total.

http://cgi.ebay.com/ebaymotors/ws/eB...m=320625216814

Wish the 2006 cool fuel was like that. It only has the standard filter/separator. It sould have had another finer filter in the pressure system. I have already had one blockage that left me stuck and was a major PIN to fix.

You might want to check your application. Maybe someone left the primary screen out. Mine is a 2006 Gen 3 cool cell for 6.2 MX MPI. My son in law is for 2005 496 and his uses the same parts. I could see how someone might do that because it could get really dirty and the dealers don't tell you about it. They want to change it themselves because its so easy.

Hmm, mine is an 06' and has the two filters just as outlined

Steve

Thank you, great idea for the DIY!

http://www.offshoreonly.com/gallery/...s/DSC_0066.JPG
This is what I took out of mine and replaced with the kit. Shipyard is the best price.

Mine came right from the factory with no screens or filters except the separator. Engine is a 6.2 L. I had it all appart last summer due to unfound blockage that dropped the pressure to the rails. I expected to find screens in both pumps but there were none.

Broken Retaining Screw
 

Hello,
I read that you snapped one of the screws off in the cool fuel filter cup. I did the same thing, I guess I over torqued the screw. Anyhow, how did you resolve the problem? I cannot find a replacement screw without purchasing a whole new cup assembly for $118.

Were you able to find a replacement screw?

How did you remove the piece broken off inside the module?

Thanks, Rob

CoolFuel II can be un-cool!
 

This is a great post and information for 2004 and up Mercruiser engine owners. Great job Guys!
The older Cool Fuel systems had an obvious spin on canister fuel water sepersator and they tended to get changed often because they were very obvious and visible. In the newer engines with Cool fuel II this (very small) filter set up is sort of out of sight and almost hidden under a simple black cap on the unit itself and tends to get overlooked quite often by boaters on the newer boats.
A lot of engine dmage we see and others report recently stems from these filter not getting changed regularly and often enough and the resulting drop in fuel flow rate and pressure drops on the newer EFI engines tend to be very damaging and many times disaterous to the engines when "lean fuel" conditions appear. With no fuel pressure monitoring and a fuel pump/filter unit that is restricted from debris and water the damage to the engine under loads can happen very quickly!
The other thing to watch out for in these CoolFuel II units especially in salt water is that they are cooled with a simple raw water differential in line fitting in the raw water line and with the fuel assembly housing being cast aluminum the can after a period both clog and rot thru putting either overheated fuel in the fuel system or even worse raw water which will quickly wipe out the entire EFI fuel system especially with salt water! You can easily unbolt the double fitting feed hose and check the condition of the system. BE CAREFUL ! As this fitting tends to get corroded in place and the small light duty plastic o-ring connectors tend to snap off easily, requiring the purchase of a whole new raw water feed assembly.
Obviously, this kind of preventive maintenance is critical to keeping you so equipped Mercruiser engines operating properly and avoiding major engine damage.
Don't forget about it or feel it's not necessary, you will find out later how important it was!

Best Regards,
Ray @ Raylar

Kind of a dumb question - for the Gen III's, where does the water that's separated from the fuel go? Does it just collect in the bottom of the plastic cup?

Water in the fuel from tank will be sperated out of suspension by the pleated filter itself and remain in the filter housing around the outside of the filter and start up from the bottom. When the filter housing is full of water the high pressure fuel pump will start starving out and most likely the engine will stall. When totally overloaded with water some water laced fuel can get through and it will start raising havoc at the injectors and fuel rail.

Its also interesting to note that the new ethanol in fuels help water molocules pass thru the water sperating fuel filters and get into the EFI system and engine where they do addtional damage. Some 496's have expeirenced rusting inside the fuel rail which clogs the injectors and this rusting is being caused by excessive amounts of moisture in the fuel system after the fuel water seperators.

If you are getting your fuel at marinas or in the water fuel stations and you suspect a lot of water may be present you can install a much larger fuel water seperator in the system and they should have drain petcocks on the bottom where the water will collect and you can drain a small amount out to test.
Bottom line is to service your Cool Fuel III at least once before each season and then during the season as use hours and issues with water dictate.

Best Regards,
Ray @ Raylar

Pulled mine today and they were pretty scuzzy. Does this look alarming? Engines seemed to run ok. Just look pretty nasty. Probably 70 hours and a few years. [ATTACH=CONFIG]561300[/ATTACH]

the tan / brown paper filter brand new can come with black on it already out of the box. Some have no black on the paper filter media and some have black on it already straight out of the box brand new. most of your black in the pics came that way already brand new.

The new filter kits have 2 O rings to change out

And the big AND is some Merc Gen III have 3 filters internally. Just depends what you got.

A little bit of more info that is not mentioned is --- you dump the fuel from the basket in a clear jar to examine it closely for water and contaminates, If water in that basket sample --- you need to check your whole fuel system for water including the gas tank. FYI