Engine vacuum question


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Old 01-17-19, 03:07 PM
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Engine vacuum question

Is reading supposed to be same at all locations? I get widely varying numbers, 23 mmHg at brake booster, 15 at multiple tubing connector, and even zero at the vacuum inlet of fuel vapor purge valve solenoid.
 
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Old 01-17-19, 03:11 PM
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Vacuum will be different at different locations.
The brake booster should be actual/full manifold vacuum.
The vapor purge valve is a controlled vacuum and will change according to computer requirements.
 
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Old 01-17-19, 03:26 PM
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Thank you much for the answer. I did the test because of zero reading from the EGR Vacuum Solenoid inlet. Is this also a computer controlled vacuum?

My vehicle is 1997 Ford F150 pickup. According to the youtube video for 2000 Ford Ranger pickup, the person felt vacuum with his finger from the hose. The hose kind of stuck on his finger.
 
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Old 01-17-19, 03:30 PM
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I would expect to see some vacuum from the purge valve as soon as the engine is started or shortly thereafter. If you don't see any vacuum you'll need to find what controls it.

Many vehicles have a vacuum road map on the ID sticker under the hood that can be followed.
 
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Old 01-23-19, 09:09 PM
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Vacuum lines deteriorated from age and were losing vacuum. Just ordered vacuum hoses and connectors online. Thank you.
 
 

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