camptappakeg69

Best upgrade I have done so far, I moved the fuel separator to the front bulkhead to make room for the return. Do yourself a favor and get rid of the merc regulator and get an adjustable with a gauge on it. I originally was going to return to the tank, but needed to get it on the water and didn't feel like gutting the whole interior to do it.

dereknkathy

this setup has fuel injection pressure in the fuel filter. so how can you use filter as a return? you are trying to put regulated down fuel into a filter that is pressurized to 45 to 65 psi.

dereknkathy

how about a T fitting right where the vent hose hits the tank? then put a loop in the vent hose up high to prevent returning fuel out the vent hole?

AllDodge

iTrader: (1)

Need to remember the first law of hydraulics (pressure exerted on a confined space is transmitted with equal force on all areas). Merc and others have run the regulator over pressure back to the fuel filter for a long time and continues to do today. Pressure can build to high levels in confined spaces but it take very little of a liquid to go from 40 psi to 2 psi when released. The motor is constantly using fuel, and returning a little fuel back to the filter (which includes, all lines back to the anti-siphon valve and up to the main fuel pump). A few cc's will drop the pressure to manageable levels.

Do agree going back to the tank is the best, but you don't want a pump to push so much more fuel then a motor can use even at WOT. Moving to much fuel, and IF the motor idles very long, or there is little fuel in the tank, the fuel will heat up. So 200 GPH for a motor which only can use 40 GPH can cause some issues

IMO

camptappakeg69

My system and the stock system did not have fuel pressure at the filter head. Filter head is before the new electric pump, which feeds filtered fuel to the pump. Pump feeds fuel to the rail which has a 10 micron filter before it enters the rail, then the other end of rail feeds the regulator where it bleeds the excess/ returns it to the filter head, instead if a return to the tank. Fuel has no pressure after it leaves the regulator.

Tractionless

I'd love to see some schematics of everyone's systems for simplicity's sake.

AllDodge

iTrader: (1)

Mine is pretty simple, tank, filter, pump, fuel rail, regulator, tank

GrannySShifting

Is your filter and pump mounted lower than your pickup in tank? Most electric pumps dont like pulling fuel uphill is what worried me. Looking to feed 900 or so hp per side, originally a VST MPI setup. I was thinking since theres no tank return, small inline pump mounted low on bulkhead to feed up to a surge tank with twin pumps in it, return from rail dumping fuel back into surge.

inline pre pump though wont be regulated. Neither is the factory mechanical pull up pump either though? Not quite sure how that works and the VST doesnt become pressurized at low fuel demands

AllDodge

iTrader: (1)

No not lower then the pick up, it's under the motor mount so that puts it just about even with the top of the tank give or take a tad

No Coast

Granny did I read your post right, your looking to supply 900 HP each engine with a modified MPI intake and modified VST pump system??