Compensation Tube

Roger - I have a 914 with the standard compensation tube with a tee for a manifold pressure connection tube.  I've gone through 3 manifold pressure sensors over several years because I eventually get the big red X on my Skyview display for manifold pressure.  It has sometimes been intermittent from flight to flight, and even during flights, but then will stay on.  Very recently I disconnected the sensor tube from the compensation tube and the sensor itself, to let things dry out for 1-2 weeks  When I reconnected it to fly, the sensor gave good readings for the first 1 hour leg of a short x-cntry flight.  But on subsequent legs I again had the big red X. I checked the compensation tube - it does not seem to leak, but was wet inside from carb fuel.  Perhaps the fuel is getting into the sensor too.  How do I correct this, or whatever might be causing the big red X?

Hi George,

I'm not sure why your having this MAP sensor failure issue.  Maybe RW can chime in.

Over the years I have seen small amounts of fuel moisture in the comp tube. Many owners have MAP sensors and don't have an issue. It may or maybe not be as simple as relocating the sensor itself up in a higher mount to prevent any liquid of any kind from getting to it. I've moved other sensors over the years including the fuel pressure senders up in a higher location and my issues on these planes went away. Just something to think of.

I also use an idle jet inside the MAP line at the tee you talk about and that stops MAP pressure pulsation, but because of the small hole it may also keep out any fluid moving down stream if the fluid is the cause.

Russ,

Have you searched McMaster-Carr?  https://www.mcmaster.com/products/fittings/shape~tee/system-of-measurement~inch/fitting-connection~barbed-2/connects-to~hose/?s=t+fitting