Good info on >>> WTB Electric Vacuum Pump 1990 ZR-1

[WB9MCW]

WYO69vette04-15-2007, 06:29 PM
I have been looking for a vacuum pump and got two replys on them. 1 for 299.00 the other for 400.00. What is the going rate for the pump or can the pump be repaired? The electric motor on the pump works fine but it doesn't shut off even when you close the vacuum lines? I thought of posing here instead of the c4 forum or should I post there also? Thanks

Bud

ittlfly04-15-2007, 08:09 PM
Are you sure you need a pump? Which side of the quick disconnect isn't holding vacuum? You need to pull a vacuum on each side. You may have a leak under the plenum or the vacuum hose itself between the disconnect and pump may be bad.

WYO69vette04-15-2007, 09:33 PM
I follow instructions from some members and disconnected the line going to the intake and closed off the line going to the pump and then also right at the pump, the pump continued to run but and with a vacuum gauge the pump doesn't creat a vacuum . I also used a hand vacuum pump and appears I also have a leak under the intake since I can't hold the vacuum using the hand pump. My luck both are bad. I don't know if you can repair the pump and don't know what the cost should be for a new or rebuilt one.

Thanks

Bud

WYO69vette04-16-2007, 01:43 PM
After looking everywhere I finally just broke down and bought the one for $299.00 off of the site we don't mention. It was the last one he had and the other 3 places I found them they wanted close to $400 for theres.
Thanks for the advice, I also couldn't find them off of the 06 Kodaic Trucks.

Bud

Here's an interesting little story.....
>
> Back at the turn of the century, I was assigned to packaging the GM
> full-size van HVAC system into a new, medium duty truck platform. While
> this concept made some sense, there was an interesting little paradox to
> make life interesting.
>
> The HVAC system had vacuum controls and actuators for everything but the
> temperature control door in the module. That was common practice way back
> in the golden age, way back before many of you could count. Not really an
> issue for a van, where there was a readily available vacuum source at the
> intake manifold......unless you were one of the small percentage of
> customers that bought a diesel. Turbo-charged diesels have pressurized
> intake manifolds, so a small vacuum pump was designed into the accessory
> drive and was belt-driven.
>
> But trucks built for medium duty are roughly 50% big block gasoline
> engines and 50% diesels. Plus the older version of medium duty's used
> electrically actuated HVAC modules, so none of the diesels had vacuum
> pumps designed into their accessory drives........Trust me, you don't want
> to know how much it costs to redesign an accessory drive on a commercial
> diesel engine. I'll bet you can guess where this is going!<g>
>
> Oh, woe is me, what to do, what to do......first was to make disparaging
> remarks about the Braniac executive that decided to use a vacuum actuated
> HVAC system on a commercial truck with 50% of them having no source of
> vacuum. While that didn't go very far towards solving the problem, I
> sure felt better!<g> Next came a shot and a beer....or two. Then came an
> epiphany! Uh, ZR1? Secondary vacuum pump? A couple of phone calls
> later, I was armed with the part number and ordered a bunch of ZR1 pumps
> to supply HVAC system vacuum on early prototype medium duty trucks.
>
> One thing about these pumps was that they didn't really have the best
> record for durability. They often became contaminated with water in the
> motor housing, that gradually led to corrosion and open circuits. Funny
> thing was that the motor housing was designed to prevent dust intrusion,
> not water. Yet pumps with no motor housing at all kept on pumping till we
> scrapped the trucks, while those with intact housings and a small pool of
> water in the bottom often needed replacement. Hehehe, we beat the cr*p
> out of those mules.
>
> A modified version of the pump was born, validated and released for
> production, with water drain holes in the motor housing. Another minor
> modification was made to the switch on/off points so the pump would
> continue its on/off functionality to elevations up to 12,000 ft. The ZR1
> version was rated to 10,000 ft. At higher elevations, the pump was unable
> to pull enough vacuum to reach the shut-off point and would run
> continuously. That might have been acceptable for the rare ZR1 spending
> extended periods at extreme elevations, but not for trucks that might
> spend much of their time there. FWIW, once the drain holes were added,
> warranty numbers on this pump improved dramatically.
>
> So, this means there is a slightly modified version of the ZR1 vacuum pump
> in current production on the Chevrolet/GMC Topkick/Kodiak with diesel
> engines, and it should be available thru GM SPO or at least thru a
> dealership that carries medium duty trucks. The mounting bracket is
> identical, as is the the electrical connector, which is a standard GM
> part.
>
> I don't have the new part number handy, but I'll dig it up tomorrow and
> send it to you. I know I posted this info years ago on the net, so if
> you're really in a hurry, you might be able to find it in the archives. I
> might even still have a couple in a box under my desk at work.
>
> BTW, F*rd did the same thing on their medium duty trucks with diesels.
> Their version of the pump uses a different electrical connector that's a
> standard F*rd part. They did not revise the switch points, nor did they
> add water drains, and "F*RD" is molded into the housing.
>
> Hope this helps....
>
> Tedster

Hehehe! Heard my ZR1Net post made it to the forum.

So after reading the posts about availability and price, just fer grins, I checked with GM Parts Direct. Lo and behold, the Kodiak/Topkick pump shows up as follows:


GM PART # 15198448
CATEGORY: All
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $147.72
OUR PRICE: $87.57

Knowing the contract price GM pays for production units, all I can say is that they are offering them at a reasonably fair retail price.

Tedster

PS: I used to have a dozen or so prototypes under my desk, but gave 'em all away.......but only to folks who stayed in the throttle long enough to actually notice the secondaries kicking out from lack of vacuum.

Old news. the vacuum pump only works for 91-95 cars though. The 90 has a different style connector.

[jonszr1]

it will work on a 90 if one changes the electrical connectors. i cut off the original connector and put 2 single female spade connectors and attached them to the 91 pump i bought . i did pop the fuse as i hooked them up wrong . switched the connectors put in a new fuse and its worked fine ever since.

[mbabbitt]

I just checked GM Parts Direct and that number didn't show up.

http://www.gmpartsdirect.com/

[WB9MCW]

Originally Posted by mbabbitt

I just checked GM Parts Direct and that number didn't show up.

http://www.gmpartsdirect.com/

Well doesn't that just figure!

Maybe the Tedster will chime in and find us the new correct #

[Hammer]

Try part number 94669091. $108 delivered from P & G Chevy. I just got one for my '91 and it bolts in and connects perfect. I believe these fit '91-up cars. Might be able to change the plugs for the '90's.

[WB9MCW]

Originally Posted by Hammer

Try part number 94669091. $108 delivered from P & G Chevy. I just got one for my '91 and it bolts in and connects perfect. I believe these fit '91-up cars. Might be able to change the plugs for the '90's.

Thnx for the update John -- $108 not a bad price vs. those $300-400 ones