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What is this port on the spider for?

ao.frog

Well Known Member
I'm wondering what the open port on the pics below is for? (Lyc IO-360)
It's marked "GAGE" so maybe it's for a fuel-pressure gage?

I'm using the fuel pressure sensor on the firewall according to the drawings, so no need for a gage port here.
If so, I guess I can just blank it out? (I have a suitable fitting)

 
Its for a fuel flow gauge that uses metered fuel pressure to indicate fuel flow. You can safely plug this port.
 
The benefit from using this port for the fuel pressure is that it shows when fuel starts to flow into the cylinders - so when priming its the best indication of when fuel actually starts to flow. It will also show the pressure of fuel delivered (which varies with throttle position). No pressure here means no fuel in the cylinders.

It can be plugged, but I think this is a more useful pressure indication than just after the fuel pump.

Pete
 
Service Port

Alf,
That fitting is a service test port. It is used to take a pressure reading, like your car mechanic would do to check the fuel pressure of your car's engine. You could remove the fitting and plug it. The PROPER thing to do, is to cap it with an AN929 cap. See

http://www.aircraftspruce.com/catalog/hapages/an929.php

The fuel distributor sees less pressure than what is seen at the fuel pump. The FI servo modifies [lowers] the pressure to the fuel distributor. Checking pressure here is done by a mechanic who is trying to diagnose a fuel injection problem.

Charlie
 
I got caught by this also

The somewhat interesting thing is that on the spyder under the fitting it says Guage. I missed that when I was asking questions.
 
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