Manifold Pressure problem

We have just over 200 hours now on N364SJ RV-7 "Miss Sandy".
Problem MP started acting erratic. 0-5psi then drops to zero.
Checked fittings from #3 cyl head up to MP sender on FW. Replaced loose 45 deg elbow(.040) at cyl head with brass male/female (1/8NPT, .040)and added the 45 back on end to accommodate 1/4" line back to sender. Used red Loktite on Pipe threads being careful to keep out of fitting orifices.
Also stuck my head under the panel and checked the little 1/8 flex tube for brittleness/cracks etc. No joy, so I suspect the MP sender. Just looking for someone who has experienced these symptoms who could confirm (before I spend another $58 at ACS) os send me in the right direction.Thanks for any help.

It should read 29.9 (sea level) engine off, not zero. Not a leak problem; either wiring or sender.

Here is how you can test the MAP sensor:

http://www.youtube.com/watch?v=B8EVhFc5Yqw

MP

Thanks guys, Ill check it tomorrow

Manifold Pressure

It was the guage...and reads OK now except on radio Transmit it goes to full
scale even after installing a grounded shield around wire run! Looking at a better shield ground? or why RF is getting into MAP & possibly Ammeter. no other instruments affected. Suspect when Nippodenso alternator failed due to a shorted diode, it spiked the H*** out of Van's guages. Oh well, we will ponder the situation and figure out the root cause...