35 White Lightning

Does anyone have a pair of the Mercruiser Cool Fuel systems they want to sell my 1995 35 w 502 MPI's vaporlock so bad [email protected]

stevesxm

you can work around it very easily. i have/had the cool fuel system when i got my motors and the first thing i noticed was that merc routes the fuel return back into the filter. i thought this a terrible idea as it just put aereated and hot fuel directly lack into the fuel flow circuit. so the first thing i did was route that back to the tank directly. that lowered the fuel temps 20 deg in the fuel log. i never had a vapor problem ever. the other thing that i did routinely was , whenever i arrived anywhere, i would always open the hatch for a few minutes especially if i was traveling slowly in the approach. that got the under hatch temps down to something lower than the surface of the sun and allowed the intake manifold and fuel log to cool off and stabilize. between the two, i never had any vapor lock issues. on the race cars that were injected that we had to shut off during pit stops that were often then hard to start, i made a fuel log bleed. that was nothing more than a fitting to which i fitted a very very small carb jet that allowed the the log to circulate back to the tank. it was small enough to bleed off any " vapor" and allow the log to fill yet wouldn't vent more than 1 psi pressure at speed which we just compensated for in the map. it solved all the problems 100 %.
of course on those cars you turned the pumps on and they stayed on... not the "on for 5 seconds and off" safety circuitry that is in use now. . . on my boat the hi pressure pump starts and runs continuously with the ignition on. you can accomplish exactly the same thing by throwing away your vst and replacing it with a stand alone hi press pump and a stand alone adjustable regulator that you install on the "exit" of the fuel rail that then returns to the tank. that way when the pump runs, it " flushes" the fuel rail out thru the regulator continuously which would make your vapor lock issues a distant memory.

bcfountain

where do you run the return line?do you add a tee fitting at the fill hose going to the gas tank?and what pressure setting do you set the regulator?can you turn up the pressure and gain more power?

Shock Therapy

If you decide to go the cool fuel route, let me know. I just pulled off my cool fuel system on two HP500EFI's. I needed more volume with the blowers than the cool fuel could deliver.

stevesxm

i ran the returns directly back to the tank. my fuel tank access port has multiple inlets/outlets, some unused so for me it was a couple of fitting and a couple of hoses and no... more fuel doesn't necessarilly mean more power. if you want to screw around with the efi for more power you are talking about either dyno time with egts to make a new and more agressive fuel and ignition map or , in the alternative, egt recorders to do the map in the boat. there are people that claim to remap the stock ecu's from stock and , without any other modification to the hardware, get big gains but i have never seen that to be the case in the real world. the factory map, while admittedly a bit conservative isn't bad at all and will serve you well. more fuel isn't going to help you at all unless it is lean somewhere in the curve or if you change something mechanical that necessitates a greater fuel flow.