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So, prior to installing a vacuum sensing switch at the outlet of the 10 micron filter
(the switch is wired to the ECM "water in fuel" contacts)
I had to decide on a set-point.
To determine current "normal" conditions
I tee'd in a vacuum gauge just before the LP pump,
removed the VST drain,
and then used YDS to run the pump.
The gauge was not sensitive enough to indicate any presence of "vacuum"
video of pump running "full out":
https://vid.me/ssDk
However, if I pinched the supply hose shut, the pump "pulled" down to ~6 inHg
video of pump running restricted:
https://vid.me/IIx3
It seems then, that even a very low amount of measurable vacuum would indicate an abnormal condition (presumably, plugged filter)
So I adjusted the vacuum switch to close at ~2 inHg.
https://vid.me/ggvG
(Although the absolute value is uncertain, given so little of the gauge's range/scale is being used)
(the switch is wired to the ECM "water in fuel" contacts)
I had to decide on a set-point.
To determine current "normal" conditions
I tee'd in a vacuum gauge just before the LP pump,
removed the VST drain,
and then used YDS to run the pump.
The gauge was not sensitive enough to indicate any presence of "vacuum"
video of pump running "full out":
https://vid.me/ssDk
However, if I pinched the supply hose shut, the pump "pulled" down to ~6 inHg
video of pump running restricted:
https://vid.me/IIx3
It seems then, that even a very low amount of measurable vacuum would indicate an abnormal condition (presumably, plugged filter)
So I adjusted the vacuum switch to close at ~2 inHg.
https://vid.me/ggvG
(Although the absolute value is uncertain, given so little of the gauge's range/scale is being used)