Janitrol heater and front engine fuel flow

[mshac]

I run my P337H at about 12.5-13 GPH per motor (maybe a bit more for the rear), and see no change when I run the heater. I think (could be wrong!) the fuel that goes to the heater is unmetered, but its a fairly miniscule amount IMHO, at most .5 GPH. My buddy put an 8000BTU diesel heater on his sailboat last winter and it uses about 3 gallons per day. Heaters are pretty darn efficient.

[n86121]

I have had a shadin for decades, but recall eons ago when I did have Ye Olde Original Fuel Flow meters.

As I recall, they worked by pressure, to indicate GPH.

If you have a fluctuating flow into the janitrol, for example as it cycles on and off, perhaps that would induce some minor change in fuel pressure, which would show up on the original gauges as minor changes of variable fuel flow?

[B2C2]

Yes, they are pressure driven. They sense the difference between the fuel system pressure and manifold pressure in my T model. So its not a direct measurement of flow. I think that a pressure fluctuation on the fuel side due to the influence of the heater is what I am seeing. Because I am running LOP, any fluctuation is noticable as a power change. If I was running ROP, I think it would be much less noticable. I have JPI unit with fuel flow meters as well. Its harder to see this kind of wobble on a digital readout. The one case where analog beats digital.