Vacuum pump
 

Still trying to learn the differences in the ZR-1 from the 96 LT-1 I have. When I turn the ignition on I hear the vacuum pump run and then shut off. How long should iut remain off before it kicks back on? Mine shuts off for a couple seconds then turns back on for about a second. The cycle repeats until I start it up. Is this normal or do I have a vacuum leak?

Re: Vacuum pump
 

I think you have a vacuum leak....once you start it up, plenum vacuum takes over. The faster the vacuum pump cycles (engine off) the greater the leak. The fact it does shut off even for a couple seconds means the leak is not extreme....but often kind of normal for vacuum lines that have become hardened with age. I think everyone has some vacuum leak more or less without knowing it. Plenum vacuum can easily compensate for small vacuum leaks such as that I think once the engine is running.

The Plenum vacuum source is that little connection center of Plenum on Drivers side. The other side of Plenum vacuum connection is Cruize and HVAC Vacuum.

If the vacuum pump does not cycle once the engine is running, that is an indication the Plenum vacuum can keep up with any small leaks. Now when Plenum vacuum drops at wide open throttle you still have sufficient vacuum with the vacuum pump keeping up with the leaks.

But I will check this out tomorrow when I fire the 91' up again :p
OOPS...that will have to wait until I fire up the 90'....I have no vacuum pump on the 91' :D

Re: Vacuum pump
 

Yep. Like Cliff said, the fact that it shut off indicates the leak isn't severe, And, aside from knowing it won't get better by itself, that much of a leak won't affect the operation of the Secondary Port Throttles (SPT as it is referred to).

The "Right of Passage" for any ZR-1 pilot is a plenum pull. So much stuff is under the plenum that sooner or later you'll want to do a "walkabout" under there. When you do, a Mitivac (hand-held vacuum pump from Harbor Freight (or the like) will come in handy to isolate the source(s).

P.

Re: Vacuum pump
 

That cycle time is way too short. The leak is too fast.

Here is some background on the secondary system on LT5s where the system is still in tack.
http://www.zr1netregistry.com/Inform...Diagnosis.aspx

First try checking that the pump itself is not the problem.
Do that by disconnecting the hose (be carful) and using your thumb plug
the side that runs to the pump. You can find a fitting on the
hose to do this where it goes over the two oil lines that
run to the radiator stack. The pump should run for a short time then
stop for as long as you plug the line.

If the pump runs again even with the line plugged then the diaphram on the pump has a hole in it.
Here is a pic of mine after I fixed it and fasioned a bracket to fit around it instead of glueing it back together.
http://zr1.net/forum/picture.php?alb...pictureid=1446

Re: Vacuum pump
 

Thanks for all the input. A plenum pull is definitely in my near future. It only has 12,000 miles and pretty sure the original injectors so they are on the list also. I have had the plenum off my 91 Z28 w/L98 for just about the same work and had the plenum off a 96 LT1 for cleaning and gasket replacement. Every coolant hose and vacuum line on the 96 was bad and needed replace.

Paul - Got a MityVac a while back. Sure was handy replaceing the rear end lube.

Scott - I'll check the pump today. Thanks.

Mike

Re: Vacuum pump
 

Vacuum pump diaphram checks out good. Guess I'll order a gasket set and pull the plenum. It needed to come off for a good cleaning anyhow. It may not be bad but it goes against my grain when it's not right.

Re: Vacuum pump
 

Gaskets and new fuel injectors ordered. Guess I know what my weekend plans are now.

Re: Vacuum pump
 

You might want to read up a bit:
http://www.zr1netregistry.com/Inform...m-Removal.aspx

Re: Vacuum pump
 

Scott - Thanks for the link. I have all the tools but the long T40. Also have a FSM. Off to a couple of my favorite shops to find a long T40. Maybe I'll luck out and find a tool truck.

Re: Vacuum pump
 

Got the vacuum leak diagnosed. Bad solenoid. I ordered one for a C2500 truck. Looks like the same solenoid but different mount. I'll try to swap the mounting bracket and see if it works. No other vacuum leaks and all the hard lines were in good shape. Not brittle like I'm used to.

Got all the way down to the starter moter and found a rats nest... literally. He chewed the insulation off the purlpe wire (starter relay?) The drain hole was clear though. He stayed to the forward end of the cavity and none of his "furnishings" made it to the back. I guess he didn't stay long though because I cant find any other chewed wires and no evidence of bones.

Last night I pulled the radiator and did the clean and inspect. Pretty bad but it didn't have any overheating issues. Better safe than sorry though.

Got a 6" T40 Torx from Amazon and it was delivered today. Worked great getting the two bolts off the plenum. Thanks again Scott.

Clean and reinstall everything with new injectors, o-rings and gaskets tomorrow. Hopefully I'll have it back together for a test drive tomorrow sometime.

Re: Vacuum pump
 

Great Job! I would suggest one addition to your punch list. Build a cooling air intake screen. Over at the NetReg site in the maintenance section there should be a write up on the how to.

Basically, I went to Home Depot and bought two pieces of gutter leaf guard, a roll of fine mesh fiberglass screen material and some plaster repair washers. I took down the center air dam, and the support bracket that holds that splitter thing across the middle of the radiator air intake opening. I used the clips on the gutter guard to make one long piece from the two small ones. Then I wrapped it in the fiberglass screen material so the seam is toward the inside of that air channel. I used the bolts for the air dam section and that center splitter bracket to hold it in place and just put everything back. Just don't forget to clean the screen every week or so so the air can get to the radiator.

:cheers:
Tom

Re: Vacuum pump
 

I agree with Tom. Put some sort of screen in there. Worth it's weight in gold. Keeps crap out and easy to clean.
There is a article with instructions on:
http://www.zr1netregistry.com/Home.aspx
Once there put your mouse over INFORMATION
then TECHNET then click on COOLING/HEATING
Once there find the article "Cooling-System--Radiator-Screen"

You can try the link below but if it's broken use the above info to get to it.
http://www.zr1netregistry.com/Inform...or-Screen.aspx

Re: Vacuum pump
 

Thanks for the recommendations. I'll put the screen in both my ZR1 and the wife's 96. The PO had hit a bird and a few other insects large enough to carry off small children. It was a pretty big mess. Off to get the solenoid, spark plugs. and what ever else I can find at the parts store.

Re: Vacuum pump
 

Got the solenoid and pulled it from its housing and installed it. Same exact issue. I pulled the solenoid back out and hooked my hand held vacuum pump/gage up and sure enough, It slowly drops vacuum just like the original one. So, I pulled the solenoid apart and it's just a pintle held in place by a spring. If I press on the back of the pintle a little, it holds a vacuum like a champ. Maybe a stronger spring but then I may have an issue overcoming the spring when it needs to activate. Going to get another from a different chain tomorrow and see if it acts the same. I'll take the pump to the store and test it before I buy it this time. I may also work on the old one to see if I can get a better seat. Maybe some lapping compund and a slow speed drill with the pintle in the seat.

If anyone has an ideas regarding this secondary solenoid , throw them at me.

Other than that everything was smooth sailing today. Cleaning took the better part of the day but the valley is clean and back together. Put some liquid insulation on the starter solenoid wire the rat chewed up, installed new gaskets for the cover in the valley, installed the new injectors from FIC, replaced all the fuel rail seals, changed the spark plugs (#8 was as much a pain as I've read but the whole evolution wsa much easier than an LT1 or an L98), and put a new belt on. Will put the plenum on after I figure out this solenoid issue and fill it with coolant.

Re: Vacuum pump
 

It's been a very long time (12-14 yrs) since I reworked the secondary vacuum lines and stuff in the V but seems to me I stretched it a bit, changed the check valve and cleaned out the vacuum reservoir while I was in there. And I turned the actuators around (they looked crooked) and bent the L bracket on them to pull straight. (used mity vac tool to test)
I haven't had to work on the secondary since (except the pump)
Out of curiosity I just went out and turned the key on. The pump rand 6-7 seconds then nothing. (waited 2min to see if it'd leak down).

Re: Vacuum pump
 

Well, Scott... Obviously, your damn pump broke again!! Time to realize the benefits of "going camando" where secondaries are concerned, and get rid of the troublesome things!! (Course you'll have to live with instantaneous throttle response, and clean secondary valves...:sign10:)

Re: Vacuum pump
 

:sign10:

Re: Vacuum pump
 

Going Commando, lol...

Re: Vacuum pump
 

Here is a link to a thread I posted on the radiator screen: http://www.zr1.net/forum/showthread.php?t=20178

Re: Vacuum pump
 

I like that way it turned out. Very clean looking.=D>

Re: Vacuum pump
 

Went to look at the other solenoid. Did the exact same thing. Leaked down from 12" vacuum in about 7 seconds. The original one in the car was better than that so I didn't buy it. I checked the rest of the secondary vacuum system and it held 12" for 5 minutes with a drop of less than .5". I'd say the rest of the system is good. The resevoir also checked good.

I think the problem in the solenoid is a metal pintle on a metal seat and a good seal without a decent amount of pressure is difficult at best. If anything contamination gets in there, it'll leak worse.

Scott - I also flipped my actuators and one wouldn't open all the way. Turned it back around and it was fine.

RacinFan - Screen looks great. That poroject is on my short list.

Car is going back together. I'm having withdrawal sysmptoms already.

Re: Vacuum pump
 

You can't just flip it. you have to flip it and bend the L bracket such that it pulls straight. The problem with leaving it where it "looks wrong" is that one (next owner or me if I forget) would be tempted to flip it later.
Every time you look at it, it's going to look wrong.
Now mine looks correct and opperates correctly.

This being backward/upside-down is all fairly well understood and there is testimony from the facory workers as this being the way the factory installed them to opperate without stickintg. That there is no doubt to.
My hack/change/modification/kludge to the system is to avoid confusion later by removing the visually upsetting alignment.
Leaving it looking funny but working ok is just fine for most I think.
Each to their own.
Some (few) even see fit to rip out the entire system because it's too hard for them to keep working properly. I think that's pretty funny.:-D

Re: Vacuum pump
 

Scott - You sound a lot like me. I didn't like the way they looked. Even though I can't see them, I know they look wrong. Next time I pull the plenum I'll "fix" the actuators. Getting ready to fill the coolant then a test start. Reading the coolant fill solutions to make sure I don't have any gotcha moments.

Re: Vacuum pump
 

I think the concensus is to leave the actuators the way they are as they are set in their ways. Now if you install new actuators you might set them so they pull straight......just saying what I do ;)

Secondary Canister Installation TIPS

Re: Vacuum pump
 

Finished putting her back together. No codes, no leaks and no abnormal issues/sounds with no go backs! Let the coolant and oil get up to temp then test drove it. Wow. Original plugs and injectors were a definite problem. Runs smooth and the power comes on smooth and fast. I used to have a 2001 Z06 and this is just as fast and the LT-5 sounds better in my opinion.

Dynomite - I used your coolant filling procedure. Perfect first time. Thanks.

Now if I could just get the ABS working she'll be 100%.

Thanks again Scott, Tom, Dynomite and RacinFan83 for being a sounding board. This is the third time going to the bottom of the top end and I still learn things every time. Cars are back in the stable. Now it's time for an adult beverage or three.

Re: Vacuum pump
 

I wanted to provide an update to the vacuum solenoid issue that I was dealing with in case someone finds this in a search. I went through 3 solenoids that were similar in form, fit and function but were housed in a different mount. All the solenoids leaked down at various rates and caused the vacuum pump to kick on from 3 to 10 seconds. I then ordered an AC/Delco solenoid part number 1997222 I found online. It holds a vacuum with no leaks. So in my experience, the newer solenoids do not hold a vacuum. If you can find a NOS part, that is the route to go. If anyone finds a new solenoid that does not leak down, please let me know. I would much rather spend $25 vice the outrageous price of an NOS part.

Re: Vacuum pump
 

Yes, either fix them or leave a note with a tie wrap near them that explains the issue. The way they look is a magnet for your eyes. It's like seeing a picture frame that is unlevel. One's inclination is to just straighten it. But in this case you have to fix it correctly by flipping and bending the L bracket then testing.

I'm glad to hear she runs again. Study well on the ABS before jumping in.