Fuel pressure sensor

[fabjab]

Not being somebody that have spent my life inside car bonnets, this might be a bit of a stupid question. What will fuel pressure tell me?

Setup is fixed pitch prop, carburated, mechanical fuel pump plus electrical fuel pump for takeoff and landing.

There is no specific pressure port for fuel pressure on the engine. Where is a good place to connect pressure sensor?

 

[dynonsupport]

Fuel pressure gives you an indication of the health of your fuel deliery system. If your fuel pressure goes low in flight - for example - time to turn on your electrical pump because your mechanical pump may have failed (or you're seconds away from running out of fuel). Before takeoff, you'd be able to use the fuel pressure sensor to ensure that your electrical pump is working. It will normally show an increase in fuel pressure when turned on.

Normally there is a port on the engine for the fuel pressure sender. We're not engine experts, but in the flow chain you want the sensor after both pumps. Maybe some forum reader/builder has thoughts? This is definitely a good question for a mechanic too.

 

[meljordan]

You don't say what engine you are running, but if it is a Lycoming, there is a fitting that screws into the mechanical fuel pump output port that has two AN connections, one for the fuel line going to the carb (or Fuel Injection) and a second that allows connection to the fuel pressure sender via a line. This part is available from Aircraft Spruce, but I don't have the catalog here, so I can't give you the part number. Of course you can always just run a tee on the line between the fuel pump and the carb and get the same sort of arrangement. In most systems you want to read the fuel pressure at the input to the carb or input to the fuel servo so you can see past every thing in the system like filters, gascolators and fuel pumps. I agree with the Dynon response that fuel pressure is valuable information. Also, setting an alarm on the fuel pressure is a great way to get a heads-up before it gets very quiet when you forget to switch tanks.

Best Regards,
Mel Jordan

 

[Ron B.(Guest)]

Another expert, with maybe a stupid question. With high wing tanks only (no fuel pump) carb. of coarse on lycoming , would a fuel pressure sensor be able to read such a small pressure, to be of any help?
Thanks Ron

 

[dynonsupport]

I don't think that fuel pressure is normally measured in aircraft that have no fuel pump at all. The measurable pressure, though, would be on the order of 1ish PSI. It would register (barely) , but not vary a whole lot unless you saw a blockage in the line.

Note that the way our probe package pricing works, you'll want to buy a complete sensor package and simply not use the fuel pressure sender. Buying the sensors/harnesses a la carte would end up increasing the overall cost a bit.

 

[frank hinde(Guest)]

If it were me I would no way rely on gravity to provide the fuel pressure (unless the FAA has its Certifed teeth in your business). I know it works but with so little pressure it would take very little restriction to stop the flow altogther...e.g a partially plugged strainer, sticky needle valve in the carb etc.

Think about it a 4 foot elavation is only roughly 1.03psi at the carb...If it were my airplane i would stick two Facet fuel pumps in parallel to jack the pressure up to about 5psi...Model 40105 are the ones you want...The 106's are a bit higher pressure and will give you closer to 7 to 8psi at the carb. Both of these pumps are good to 30GPH I think.

These pumps should be available at your local autoparts stroe and you should wire them from two independant electrical sources.

As mentioned above though fuel pressure really is an essential piece of infor, especially when you have a nice audible alarm feature for low pressure.

Hope this helps

Frank

 

[fabjab]

I am just about done with the installation and have decided to not install the fuel pressure sensor for now.

The manual states that I can turn the DISPLAY parameter ON and OFF (p38). I do however not see such a function in the setup? It has been a long day, including calibrating fuel levels, so maybe the fumes just got to me?

Blue skies,

Carl.

 

[dynonsupport]

In the menu system, go to SETUP|GLOBAL, then scroll to "INFO BARS CONFIG" and set the info bar that is currently set to fuel pressure to "none".

 

[fabjab]

Yep, got that sorted out, but what about the display on the fuel computer page?

 

[dynonsupport]

You're right - today there is not a way to remove it. This looks like a bug, and we'll get it fixed in a future software release.