Fuel Temperature & Injector Pump

[KingNuzz]

I have a mechanically injected 6.5 and am setting up a coolant loop heater in the fuel tank to prevent gelling with biodiesel blend in winter. The truck has 180-190 degree thermostats and '97 cooling upgrades; see signature. The temp guage seems to run around 150-160 under normal use. I occasionally tow a tractor on a flatbed trailer with a towed weight around 9,000 lbs. I live in upstate New York, with temps as low as -30 and as high as 95 degrees

My question is: During summer use, would the coolant-heated biodiesel or blended fuel be too hot for the injector pump or injectors? If so, I should have a valve or shutoff thermostat. I've read that the newer electronic engines with high pressure injection systems rely on fuel to keep the pump cool. How does the Stanadyne pump handle "warm" fuel?

Thanks.

[tom.mcinerney]

King--The '94-2000 6.5L are fitted with a fuel filter assembly incorporating an electric 100Watt heater that is thermostatically regulated to heat fuel from below 40* to about 80*F. The volume of fuel in the tank is relied on as a heat-exchange 'sink' to cool an electronic module attached to the pump, that is, prevent it getting too hot. My guess is you wouldn't want your diesel fuel to rise over about 120*F, but that only a guess. The apt cutoff would depend on the viscosity and flammability of the particular fuel. Large stationary and marine diesels burn stuff that's waxy/rubbery/tarlike at room temp.
Not long ago i saw an advertisement for a thermostat designed to be used to maintain fuel at {if i remember correctly} about 80*F by regulating flow through an engine-coolant/diesel fuel [liquid/liquid] heat exchanger. These are commercially available.