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Manifold pressure filter


Well-Known Member
Feb 9, 2014
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My manifold pressure comes from a fitting at the bottom rear of #3 cylinder head. This is directly below the fuel injector, and I think fuel gets in the line every time I prime the engine to start. As a result, every 15 or so cold starts the filter in the line plugs with gas residue and the gauge becomes laggy. I'm getting tired of pulling the filter to clean it out with acetone. I'm wondering if there is an alternate source of manifold pressure that won't cause this problem. Or perhaps there is a special fitting for the port in the head that minimizes it.

Engine is a stock Lycoming parallel valve IO 360 B1H and the sender / filter is for a Visions Microsystems 1000. The filter is a fine mesh of some sort built into the fitting that screws into the sender. (It's very fine - after cleaning it takes about 2 seconds to push a ml of acetone through it with 40 psi.) I assume it's there to dampen the pressure variations. I've been told it's not really needed, but removing it would just let the gas residue into the sender which is much more work to clean out than the filter.

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