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post #3 of Old 11-01-2019
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Re: Racor fuel vacuum guages

Here's a method to assay the correct 'when to change out the damn filters'.

Install a vac between the engine lift pump and the last filter in series. You can add other vac gages between each filter for greater control/observation.
All filters newly installed
Run fully warmed engine with trans in forward and boat securely tied to dock.
Run engine at WOT- wide open throttle ... as you slowly close the tank valve ... until the engine begins to 'stumble'
Record the vacuum reading at 'stumble'. Multiply that number by .85 (leaves you 15% of reserve in case Murphy comes calling.)
Periodically 'test' the engine and the vac gage at WOT ... if the vacuum is approaching that .85 value ... its time to change filters.

If you want to get fancy, install an electric vac switch (12vdc wired to an alarm) between the lift pump and the vac gage. with its set point adjusted to set off an alarm at the .85 value.
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