It's a 91 f150. It just got out of the shop because I couldn't diagnose the ignition problem. The mechanic said everything looks ok but the vacuum pump may go out soon. I did some price research and its about a $200 part. What does this part actually do? Is the truck going to completely crap out when I'm driving if this thing goes out? If it's something I can live without can I buy a shorter belt and just bypass the pump? Thanks in advance.

 

Im not totally sure what the vacume pump does but i know that it pumps air into the intake manafold, the exhaust manifold or head (depending on your vehicle), and into the cat. The purpose of this is to make the truck apear as if its running cleaner. i have not heard of any options of a air pump delete kit or anything like that but i would keep looking. I dont know if getting rid of that will screw up the air to fuel ratios because, depending on the vehicle, if it pumps the air into the head then there may be less air, in the air to fuel mixture, if you were to get rid of the pump.

I.6.O.D

 

There ain't no vacuum pump on that F150, what ya'll got there is an AIR pump, which does absolutely nothing for the engine's proper operation, but it does help reduce emissions when cold by blowing air in the cats. So really as long as the pump don't physically seize it's all good regardless of how much air it actually moves, and if it does show signs of seizing up just use a shorter belt if you can (may have to route it differently tho) and bypass it. Do you have emissions testing in your area?

 

Yes I do have emissions testing in my area. My mechanic that I use I have used him for years and is one of the best in Springfield, IL. He said it was a vacuum pump...he said if it goes out my power steering or something may go out. And when I search on autozone.com under 91 f150 a vacuum pump comes up so there obviously is one on the truck.

 

Springfield has emission testing? I never knew downstate IL had areas with testing, I'll stick to the Champaign area if that is the case. I'll second what the others are saying, there is no vacuum pump on your F150.

EDIT: I stand corrected, there is a vacuum pump listed at Autozone for a 1991 F-150 w/5.0L engine! I wonder where it's located on the engine? Maybe it is a misprint and it's actually for a larger truck with 7.3L diesel?

 

Next time you talk to your mechanic, have him write down the problem on paper for you so you can remember what he said...

 

No surprise here, it is Autozone afterall.......

 

Well I'm going to take your words for it and say there is not vacuum pump. I'm a newbie to this old truck thing...I got it cheap and gonna use it for a work truck so I'm relying on all of you for your education and useful info

 

Well I ain't never seen a vacuum pump on an F150, at least not one installed from the factory. Ford put vacuum pumps on their diesel trucks to operate the vacuum brake booster and the HVAC system, but gassers make good manifold vacuum so there's no need for a separate pump. Your power steering on the other hand is a hydraulic system, and as such utilizes a high-pressure hydraulic pump that runs on Type-F transmission fluid, and not vacuum. So you see, even if there was a real vacuum pump in your truck, it would not be linked to you power steering in any way. Unless!!! Your truck uses a serpentine belt, it's one belt that drives all the engine accesories, including the AIR pump. It's a convenient setup but it has one major downside - if one of the accessories seizes up for whatever reason then the belt will overheat from slipping on it and will eventually snap, thus disabling all the other accessories. So in such indirect way it is possible for your AIR pump to disable the power steering when it finally dies, it will also disable the alternator and the water pump, making the situation that much more lovely

 

My 55 F100 had a vacuum booster pump on top of the fuel pump to drive the windshield wipers.

 

Cheaper at Advance...
Vacuum Pump by BWD - Part VDV20 - Advance Auto Parts

Doesn't show one for my '95 with the same engine.

 

I thought the same thing so I went to Advance Auto and Oreilly both of them list the pump too. Oreilly has a good listing by application of what the pump fits, no oil-burners listed...

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I hope someone can chime in and point out why it is used on gas engines from the 1987-1993 range and where it fits.

 

Bill...you're killin' me

 

Subford, but your '55 ain't no EFI - I do agree with you tho, vacuum pumps are the sign of coolness in a truck

That's the exact same thing that I have in my diesel, runs the brakes (well it used to) and the HVAC system. Same pump lives in Dodge and GM diesels (Hummers included), as well as apparently in some big trailers - there are slight variations in shaft length and diameter, but the essentially it's all the same thing. Never ever have I seen one of those critters in a fuel-injected Ford gasser...