Ron may remember what he used for temp switch, it's a furnace limit switch I'm guessing low 100s (130) it may be marked on the part
2 wires go to it small round disc with 2 screw holes opposite from each other
the idea was to have the blower turn on when under hood temps rise (usually hottest after the boat has been turned off)
the blower on was to help remove some of the hot air and introduce cooler air all in an attempt to prevent
vapor lock.............. an old issue but new (@ the time) to the marine industry where EFI was starting to become more and more popular
unlike your automotive EFI the fuel pump is in the fuel tank surrounded by cool fuel and also allowed to remain under pressure
on the marine side @ that time and still required by all (but one) is to have the fuel pump out of the fuel tank and the system has to depressurize
when the ignition is off, understandably, not many of us would want a hose rupture on our watercraft while our fuel system is constantly pressurized............
until you turn the key to start it then you want instant starting like in your modern car. the Marine Engine Mfgs understand this and try to keep the fuel pumps as close to the
point of injection as possible so the "lag time" between turning the key and actually running is minimal............. if the fuel drains from the pumps to eliminate the pressure when off
and you have high under hood temps, you have a high risk of remaining fuel in the lines around the engine to vaporize and therefore the pump has nothing to grab
vapor lock issues on EFI marine engines can do 1 of a few different things........
crank and crank and crank and not fire, having to let it sit with the hood up and try to re-prime the pumps an hour later
fire and run just long enough to get it in gear and away from the dock then die only to crank and crank and crank and not fire,
having to let it sit with the hood up and try to re-prime the pumps an hour later
What seemed to work the best for us in upper Midwest where we have a different blend of fuel every month was to reroute the fuel lines (approved by the engineer @ Marine Power)
from the tank to the low pressure pump
low pressure pump to the water separator
water separator to the high pressure pump
high pressure pump to the injection ( no change here)
you MUST keep the return line running all the way back to the tank
any fuel drained from the high pressure pump remained in the cool water separator
and pushed through by the low pressure pump instead of the low pressure having to draw from the water separator
with this setup I don't recall ever having a vapor lock issue
good luck
sorry of the long answer on an easy question
Dan T
