COOL FUEL?

rasbury

I'm looking at the service manual and looking at the fuel routing, it would not appear I have the cool fuel option? I have a 2005 350 MPI motor....my fuel line goes to a fuel water seperator on the left hand side of the motor (looking from the front) and then there is the fuel pump on that same side...looking at the manual, if I had cool fuel then the pump would be on the RH side by the "cool fuel", what the heck is it anyway?

F1100

Cool fuel is a fuel cooler unit usually used on return type systems.

DanD2

My old boat had the Gen III cool fuel module and it was not on a return type system. The module was located just under the alternator and housed the fuel filter 

frenchship

It is a system that cool the fuel so there is no vapor lock. Also has two fuel filter in the same unit.

F1100

On some diesels the actually use it to cool the ECU as well.... crazy as that sounds.

In most cases the thermal sink of the fuel tank volume is enough to not warrant fuel coolers. They can provide a slight boost in power if the fuel temp can be stabilized.

same racers even cool the fuel to low temps below ambiant even to extract more power

Robs_232

Ras,

I am attaching a link to a site showing Merc engine parts by categories. The page I am linking to is the page where you will need to choose your engine serial number. Click on your engine serial number range and you can look through all your engine parts. There have been some service bulletins regarding cool fuel on the 350 Mags. Also realize that if your serial number is close to a switch check the range above or below as there may be some carry over. I think that is the case on some of the pre-fuel separator filter you were inquiring about on another thread.

http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=350+MAG+MPI+ALPHA/BRAVO

I also use this site for my B3 drive.

Rob

raybo3

My 2002 342FV has it....... Hard to believe that a 2005 would not....

rasbury

I need to contact rinker and see if they can give me the serial number...the sticker on the throttle body you can't read it and I can't get to the back of the motor and see anything, any idea for someone to contact there? Thanks for the link Rob, I will save that as I'm sure that will ne helpful. I looked at the service manual about the cool fuel but did not see any filters- if indeed I have this, and there are filters there, no I really need another in line filter?

rasbury

I looked a the manual again, and I do have a fuel pump that looks like the one used with the cool fuel system, but I swear I do not have those other components which is why perhaps I have the in line fuel filter. I have the boat and home and putting it back in storage tonight but will take a look...and will take pictures! The fuel pump and fuel water separator are right there by the raw water pump. I also have a closed cooling system, not sure if that would make a difference but will look again tonight....really has be curious! When I look in the manual, I do not see any filters associated with the cool fuel but all of this deserves further looking into for sure...if I do have filters, then they have probably never been changed... 

Cableguy Greg

If you have a screw on fuel/water separator, then you do NOT have a cool fuel filter.

212rowboat

don't let that name fool ya... yeah, cooler fuel makes for more power in a big way (why else would drag racers sacrifice the weight of those things if they didn't?)... but methinks this has more to do with mr. coast guard... fuel return lines from the engine are illegal... little reservoirs of fuel under pressure w/ intent to 'cool' it, apparently, isn't... 

there are EFI systems (namely first and second gen mopar) that don't utilize a return, but that isn't the best way to do it... 

F1100

why would a return line be illegal?

I guess it depends what you consider "big" power (drag racers super cool their fuel, its not ambiant  cooled) Its not the same thing.

rasbury

well, had only a quick look but I really don't think I do. I have had the raw water pump out three times-there are no water hoses, no box/cover(could have been removed?). Fuel tank to spin on type fuel/water separator and then-well can't feel the line to the fuel rail. It does not seem to go up into a cooler that has water lines that the service manual I have. Perhaps as a closed loop it does it somewhere else in the cooling system-and 212, way over my head ...I guess with fuel under pressure you have to have a way to bleed off unneeded  pressure and that's fuel? Looking at the manual with cool fuel, I don't see where there would be room for any filters from the pump outlet to the cooling tube.....geesh

212rowboat

F1100 said:

why would a return line be illegal?

I guess it depends what you consider "big" power (drag racers super cool their fuel, its not ambiant  cooled) Its not the same thing.

five and one half ounces is all the 'allowed' spill if any line (hard or soft) severs as per USCG regs... a true (gasoline) fuel return would blow that out just releasing it's pressure.  even on a four banger or outboard..  many makers just recirculate w/o leaving the engines hardware, especially in outboards.

and I was referring to super cool.. ambient ain't helping much. which is why the notion of a 'cool fuel' on the mercs is something I ain't buying...