Cool Fuel, VL and New Pump Discussion
 

Yada yada stuff (no real need to read), Merc and others have had Vapor Lock (VL) ever since fuel injection started. They route the over pressure back to the fuel filter and this is a bad idea. So Merc had Gen 1 Cool Fuel (CF) with a single pump port side. This did not help much so Merc adds a boost pump (low pressure) to feed the high pressure pump. Again this did not work, so they try Gen 3 CF and install both pumps in same container and use venturi effect to move cooling water thru the assembly. This helps but does not eliminate, and the cost of their special filter goes up yet again.

The fix is what manufactures like Indmar have routed their return lines back to the tank and this has eliminated VL.

Yada done
The Gen 2 and 3 CF produce the same pressure, and the control is from the regulator. Even the EC (Cat motors) use both Gen CF modules. The difference is if the boat has an Alpha or Bravo drive. The Alpha gets Gen 2 and the Bravo gets Gen 3. Since the regulator controls pressure and this is the main concern for EC or Non-EC to me this is the major issue.

The question; why wouldn't anyone remove the Gen 3 CF module and just install the Gen 2 with a regular canister fuel filter? What are the implications/concerns?

Current --- all wake boats and I mean all of them no matter of engine installed --- all mount fuel pumps in the gas tank --- zero cool fuel and zero VL and im in super hot water and air temps for the whole summer.. Some have installed this way for many years without issues.

Just don't see any reason why someone would leave Gen 3 on a boat once they have any kind of issue or just decide to replace the high priced no benefit system, or am I missing something?

That is probably right, just haven't found yet.
I'm still finding Gen 3 with 377 Scorpion Base and HO EC
https://www.mercruiserparts.com/scor...488-thru-1a092

PCM (Engines for Nautique and Centurion) do not have in tank pumps - uses lift and HP pump with an internal dump return in the FCC... no issues with VL... and easy to service

Okay acronym abusers, what is FCC ? Fuel control ..... ?

FCC = FUEL CONTROL CELL

Its like SB = SERVICE BULLETINS

MIS = Marine industry stuff

Cell...the link below shows a update kit from Nautique from an extinct older version - pump and filter are in one unit mounted top right (vertical on the front of the engine - short runs to injectors and return) and the lift pump

https://www.nautiqueparts.com/product/retro-fcc-kit/

the newer version is this they have been using the FCC for over 20 years for efi engines. and that is correct PCM in not tank mounted - its external. The FCC still needs to be serviced. https://cimg5.ibsrv.net/gimg/www.off...f3cd01ef97.jpg

To add to the discussion, not seeing why it even needs to be cool fuel at all, so long as the pump and regulator keeps pressure as specified by the manufacture

From my understanding, Cool fuel was developed for VL by dropping the liquid fuel temp in efforts to broaden the window before the fuel in the lines started to create a lock....

I called my former tech and he too, has never encountered an issue with VL in the Nautique system... as BUP said, it's 20+ years old, still in use and easy to service - even the FCC filter is a viable filter system vs. what collects in a cool fuel... this FCC system supports the big motors - XR7 and XS7 (550SC/hp) towboat

Pic from PCM website - red vertical canister that is under Alternator

https://cimg0.ibsrv.net/gimg/www.off...b8384fb9b0.jpg