Vacume pump question.
Thread Starter
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Senior User
Joined: May 2008
Posts: 387
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From: Bald Knob AR
Vacume pump question.
When I start my 90 model up with the controls set to A/C it takes about 15 to 20 seconds for the vacume pump to build enough vacume for the controls to switch and start blowing air out the vents. Is this normal or is my pump getting weak?
Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
How are your brakes?
When the vacuum pump gets real bad, you will only get air out of the defrost vents and you will be standing on the brake pedal to slow down.
But it does sound like you pump is getting weak or you have a leak in the vacuum system.
When the vacuum pump gets real bad, you will only get air out of the defrost vents and you will be standing on the brake pedal to slow down.
But it does sound like you pump is getting weak or you have a leak in the vacuum system.
Postmaster
Joined: Apr 2008
Posts: 4,802
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What he said, you'll get hard brake pedal well before your HVAC starts feeling the effects of a failing vacuum pump. I know for sure the HVAC of your truck does not have a vaccum canister, so that gets ruled out, and if brake assist is good I'd suggest looking for a vacuum leak as well.
Thread Starter
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Senior User
Joined: May 2008
Posts: 387
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From: Bald Knob AR
Same thing with the brakes. When I first start the truck it takes about 20 seconds before I have power assist to the brakes. After that they work like they should. If I pump the brakes 4 or 5 times the pedal will get hard until the vacuum catches back up.
Postmaster
Joined: Apr 2008
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Okay then, vacuum pump it is. Runs for like $100 or so from the parts stores, dunno about the dealers but I ain't never been rich enough to shop there anyways 
If you wanna hydroboost, now's the time, then you won't be needing new vacuum pump.
If you wanna hydroboost, now's the time, then you won't be needing new vacuum pump.
New User
Joined: Jul 2009
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Mine went bad not long ago. Only could brake by down shifting it was terrible. Anyway you can tell the pump has gone bad by taking the belt off of the pulley and spining it by hand. It should be as hard to turn as the flywheel on a lawn mower engine. Be warned though that the pulley does not come with the new pump, you need to by a puller or have a shop pull it off and press it on to the new pump.
