I'm trying to get my new vaccuum gauge to work with my newly installed OM616 in my vintage Land Rover. Currently it's hooked up to a 'T' in the vac line that comes directly from the vac pump to the brake booster. The other side of the same 'T' goes to a manual vaccuum actuated shut-off switch for engine shut-down. As it is set up right now, the guage won't read anything until I activate the vaccuum shut-off switch. Upon hitting the button on the switch, the gauge will quickly react and then die back down to zero as the motor quits. I just happenned to notice too that the manual vaccuum switch is also in a way that when I barely push on the button (not enough to shut the engine down) the guage will read god and strong and accurate as long as I hod the button down part way.

I obviously would like the guage to read vac pressure under normal operating conditions (ie. NOT just when shutting the motor down!). Can anyone recommend a different installation of the gauge line? Perhaps to the other large line going into the vac pump (from the air filter?)???

Thanks!

I'm puzzled. Seems to me the gauge should work in that location. Why isn't there vacuum going to the input side of your shut off switch at all times? Seems like the behavior you describe should be happening between the shut off switch and the shut off valve. It won't work in the air filter line since that is the exhaust for the vacuum pump.

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when running:
the shutoff valve is vented to atmosphere through the key switch = no vacuum possible on this circuit.






Have a great day.

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It sounds like you've got it teed in the wrong side of the switch - between the switch and the shut off valve.

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