REFLECTOR: Fuel Flow Sensor

[Jim Sower]

I've often wondered how to do fuel flow on a regulated/bypass system.  I 
settled on the scheme you have described.  My fuel flow sender is not 
supposed to be downstream of high pressure pumps so that fits right in 
with putting it upstream of the sump.  The scheme I mean to implement 
also has a single feed from the right strake to the sump and a Facet 
pump to transfer from the left strake to the right strake.  I'm thinking 
that the worst that could happen is fuel flow jumping around a little, 
and I can't think of a reason why it should to this.
Let me know how it works ... Jim S.

NMFlyer1 at aol.com wrote:

> I have a question on my fuel flow sensor placement.
>  
> My setup is a little different than most Velocities. My 173 FGE has a 
> 2-electric fuel pump manifold with an inlet line, engine line, and 
> regulated return line. The regulator keeps the engine pressure side at 
> 25psi, the rest "T's" back in before the inlet line but after the filter.
> My fuel Injection is on TOP of my aluminum V-6. All the plumbing is on 
> the cabin side of the firewall except from the bulkhead fitting to the 
> fuel servo.
>  
> The instructions on the flow sensor say that it needs to be placed 
> with the wires in the "up" position, and that a "reasonable" straight 
> section of tubing proceed the sensor inlet.
>  
> It also _recommends_ that it be placed after the fuel pump(s).
>  
> I don't have a reasonable area where I can meet all the requirements 
> and the recomendation that it be after the pumps.
> I can place it in front of the sump, 6" downstream of the sump elbow, 
> with a straight run after that meets all the requirements. The flow is 
> then up to the fuel filter, through the recirculation "T" and to the 
> pump inlet. What it does not do is place the sensor after the pumps.  
> I do believe it is far enough away from all the pumps/recirculation 
> line and filter to avoid any turbulence that would confuse it.
>  
> Since the recirculation takes place after the sensor, and returns 
> after the sensor (and well downstream), It measures the amount of fuel 
> that leaves the sump. This should equal the amount of fuel that the 
> engine is using (barring a big leak!).
>  
>  I can not think of a reason that would require the flow sensor be 
> after the pumps in my setup, unless there is some flow concern that I 
> am missing.
>  
> The exit line from the pumps runs upward from the pumps, through the 
> pressure sensor "T" and to the firewall bulkhead connector.
>  
> Any input would be appreciated.
> Kurt Winker
> 173 FGE.... bending fuel line.
>  
>
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