Can anyone tell me what this is.

 

Some type of regulated return system

 

Looks like a fuel heater to me.

 

I thought fuel heater too. But why in the world would it need two.

 

The element in the filter housing is prone to failure, and it isn't nearly adequate. Is yours still connected?

 

Yes it's still working

 

Sounded familiar, found a post regarding it from Y2KW57. LINKY LINKY

 

Looks like a fuel heater for a veggie/WVO system. Do you know the history of this rig?

 

From someplace reallllly cold.

 

It is a supplemental fuel heater. But instead of heating the fuel that goes into the engine, it heats the fuel being returned back to the tank.

This exchanger was designed by Racor, and was adapted by Ford and actually sold by Ford (has an official Ford part number) for the 7.3L. Ford even issued a TSB detailing the installation of this component, which Ford supplied with a mounting plate for the top of the alternator, the two hard fuel return rerouting lines, and the heater hose rerouting line, along with the requisite fittings needed to complete the install. Racor also sold the exchanger separately.

In the stock fuel system, the excess fuel rejected and returned by the regulator (technically, a regulated return, but it isn't called that in aftermarket parlance) does not get a chance to "heat up" in the heads before it is returned. Hence there is no mechanism to heat the fuel in the tank prior to it gelling and getting stalled before it can even be pumped.

Therefore, the two different fuel heaters are not redundant. The bowl heater heats the fuel about to be consumed, and the auxiliary heater uses engine coolant to maintain the fuel supply temperature prior to the fuel pump.