Engine External vacuum pump

Jimmer009 · May 20, 2022

So my set up is stock bottom end, speed master 2.02 190cc heads x303 cam with megasquirt.

My question is can I use a external vacuum pump for my brake booster (I'll just cap off the line from the intake manifold) to increase vacuum in the intake manifold???

I idle at about 50kpa and would like lower this number, closer to where I was stock. Is the brake booster a constant draw on the vacuum???

manicmechanic007 · May 20, 2022

Not a constant draw of vacuum
Only when you hit the brakes
Repeated application of the brakes depletes the reservoir (booster)
Quite a few cars and trucks have either electric or belt driven vacuum pumps these days
Good luck
I would run both intake and the pump
I would use one way valves on both supplies and between them as well

Jimmer009 · May 20, 2022

ok thank you.

junkyardwarrior · May 24, 2022

some of the early powerstroke diesels had a belt driven pump. Wasn't very big. I can see it being useful for the brakes, and it might even fit in the smog pump bracket. If you can find one at a JY, grab it and try it.

Diesels (at least then) didn't have any vacuum so they had to use hydroboost or a belt driven vacuum pump. I have a '95, my truck but my dad drives it since I'm working on his car for him. IIRC 94.5 through 97 were mostly the same as far as vacuum pumps. They ran the power brakes, 4x4 hubs, oh and also the a/c and heater controls. Should be plenty for a fox body I would think.

Some say that their early powerstrokes suffered from fade but that was a master cylinder problem, which mine had too-until I tossed a new/updated one on. I've been hard and repeated on the brakes intentionally and it's never once given me any issue.

7991LXnSHO · May 25, 2022

I want an electric pump and an tank. I need to do some research and figure out where to put them.

Jimmer009 · May 25, 2022

So I don't have a big enough problem with vacuum when I'm driving. My goal would just be to make to idle better. I do think a tank would be a good thing. But a diesel pump would be over kill. Thank you for the info and help.

7991LXnSHO · May 25, 2022

Jimmer009 said:
So I don't have a big enough problem with vacuum when I'm driving. My goal would just be to make to idle better. I do think a tank would be a good thing. But a diesel pump would be over kill. Thank you for the info and help.

This is not going to help your idle. Fixing any vac leaks and then carefully going through the Surging Idle Checklist will give you the best idle from your parts combo.

Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

www.stangnet.com

Jimmer009 · May 25, 2022

So the x303 cam has a lot of over lap. So no vacuum leaks. I was just trying to find a way to help it. But it is what is.

7991LXnSHO · May 25, 2022

Jimmer009 said:
So the x303 cam has a lot of over lap. So no vacuum leaks. I was just trying to find a way to help it. But it is what is.

I don’t know your level of mechanical aptitude and thoroughness as you are a new member.
So please let us know how you are sure there are no vac leaks. There are old school and newer tech ways to check. Please let us know what you did.

Even the old hard lines can be leaking by now. I recently found out my PCV valve was out of the grommet and was making my cam lumpier.
Pushing on the brake pedal should not cause your idle to change. If it does, I’d be checking the booster.

Jimmer009 · May 25, 2022

So I have a garage and lift and every snap on tool you would ever want. I installed the h/c/I myself. And just recently did the rear end gears with a track lok carrier. I also help out at a automotive machine shop on the side.

My PCv vents to atmosphere now but I the valve covers going to the throttle body. I just need to get another t and some vac hose.

but as far as a vac leak the map sensor on tuner studio is reading is what I'm going off of. Plus I have a lot of vac lines unplugged. Like the ac shut off at wot solenoid.

from a ton research and help here on I found that when changed plugs to the autolite 24's I needed to get autolite 3924's. As the reach is longer and I was fighting a misfire.

but I was thinking the brake booster was a constant draw of vacuum. So running it off of a external pump would give me more witch was my hope but not the case.

7991LXnSHO · May 25, 2022

If the booster diaphragm is leaking, it will throw off your tuning. If you block off the line and your tuner suite or a vac gauge reads higher, it’s a problem.

Jimmer009 · May 25, 2022

Thanks. I tryed that. My cam just don't a ton of vacuum.

90sickfox · May 29, 2022

Chevy Cruze has a vacuum pump that has the relay plugged to it. Very easy to snatch at a junk yard ( I have one in my car because of my xe282hr comp cam ). They are also on the doge caravans and just about all the newer v6 and 4 cylinder cars. I chose the cruise because it's easy to pull everything you need. There's even a vacuum switch and all the check valves on the hose going to the booster. ( tan connector ). Very easy to wire up and comes on when booster vacuum drops below 16in.hg.

Jimmer009 · May 29, 2022

That looks pretty slick. Any pics of your install??? I like the way it's a all in one set up. Relay and vacuum switch built right in. Thanks for info.

90sickfox · May 29, 2022

It's in my build thread.

manicmechanic007 · May 30, 2022

Damn straight looks real nice

Mustang5L5 · May 30, 2022

That’s pretty slick.

Engine External vacuum pump

Jimmer009

Member

manicmechanic007

Jimmer009

Member

junkyardwarrior

Well-Known Member

7991LXnSHO

wanna catch the space herp

Jimmer009

Member

7991LXnSHO

wanna catch the space herp

Help me create the "Surging Idle Checklist"

Jimmer009

Member

7991LXnSHO

wanna catch the space herp

Jimmer009

Member

7991LXnSHO

wanna catch the space herp

Jimmer009

Member

90sickfox

Wasn't a pretty sight...and I've got big hands

Jimmer009

Member

90sickfox

Wasn't a pretty sight...and I've got big hands

manicmechanic007

Mustang5L5

That is…until I whipped out my Bissell

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