Cash tanks for twin Merc 2.5's

[Toffen]

Hi!
I hope everyting is fine in sunny US! Here is the worst winter since 1968, and its still snowing...
I have bought two Merc 2.5 EFI SS engines 2002 models (280 hp with 260 electronics) for my Phantom 25.
I have been reccommended to install two cashtanks (smaller fuel tanks of 5 liter each) between the fuel tank and the engines, and double sets of fuelpumps. Have anyone of you experience with this set up? And do you know if any dealer selling the cashtanks, or should I get someone to make them locally?
Cheeeers and thanks, Toffen G

[Towndrunk]

I just run the return line into the same regular gas tank.

[timebomb1]

Yep, low pressure fuel pump from the main tank to the aux tank. High pressure fuel pump after the aux tank, with the return from the efi rail back into the aux tank. Keeps the high pressure pump always primed, no matter what type of water conditions. There also need to be a set of filters. One before each pump. High flow pumps and fitlers, 3/8 fuel line works the best.
The tank I have was built to fit the boat, so have one fabbed up with NPT/AN fitting bosses welded into it.
Mock one up with 4 or 5 inch pvc pipe and end caps to see how everything will fit. Good luck Gary

[Toffen]

Hi!
I have run a Promax 300 with a Torquemaster lower unit since 1999 without any gearfailure. I have shifted gear at normal idle (600 rpms) without any problem.
I will use twin 2002 Merc 2.5 EFI SS engines this summer. I have seen that someone starts the engines in gear. Does this make sense anymore with a 2002 Sportmaster lowers? I will use props with Flo-Torq II hubs.
Cheeeers, Toffen G

[Daytona19]

It makes sense to start in gear. It keeps them from slamming into gear and will help prolong your gear life. I have a 2.5 merc and never did this before this unit but all who have 2.4's, 2.5's and 300 x do this in our boat club. Also the small gas tanks are a good thing and I didnt have one in my daytona when first bought but I sure did after a summer of running and actually had it stop a few times because the fuel would run away from the tank pickups under decelleration (spelling ???)So by adding the small tanks you will eliminate this, it can cause a lean issue by not having them and fry a motor.

[Toffen]

HI!
Thanks! Engines back home now, ready for installment. :rollside:
Cheeeers, Toffen G

[randy77zt]

i had a mirage with a 260 and always started in gear.the promax computor slows the idle down when shifting but the 2.5s dont have a technically advanced ecm.they wont idle as slow either.for the surge tanks some people use a very small fuel cell because they usually have threaded fittings allready welded on.the 300 pm basically has a surge tank mounted on the motor.automotive gas tanks on modern efi cars have baffles or a sump to keep the intake pump always submerged even if the car is cornering hard.most boat tanks are not enginnered for efi.so i well enginnered fuel system will save the motors from lean-out on rough water.my talon 22 i just bought has a 300 pm on it and i suspect the fuel pump might be going out.merc wants $700 for the high pressure pump.it might get something else instead.

[Toffen]

Hi!
What kind of fuel pumps are recommended to use?
With my PM 300 SVS I used a Holley pump feeding the engine's own Mercury fuel pump. Since I will use surge tanks, I presume I have to use two different kind of fuel pumps?
Starting rigging next week. Looking forward to sun and ocean swells. Its been one of the hardest winters down here since 1968...
Cheeeers, Toffen G