Hodos

I've been battling a vacuum leak prob for a while on my 90z. I traced it to the actuator solenoid for the secondaries. It was coming out of the air port on the front. Thought it was a bad solenoid. New part arrives, install it and the vacuum leak is fixed. Amazed by my awesome mechanical abilities, I can't help but dance a little jig and drink some beer.

Next time I'm out driving, I wanted to liven the Beast up a little and punched the gas. Whammmie!!! At 3000 RPM I hit some rev limiter and have to pussyfoot home. The vacuum leak is back (same place) as well as the SES Code 61. Following the service manual, it looks like I need a new ECM. Anyone have some advice, before I tackle that bitch!

The car has less than 6k and as far as I know is all stock except the battery and some dumb alarm system that I quickly removed.

Thanks...

SAM/CH ZR-1

Can you hear the vacum pump runing when you turn on the key (without starting the engine)?

Did you check with the testlight if you have power at the solenoid connector?

Sam

Hodos

Yeah, the pump runs continuously. I've got the test light "on" with it going to ground, but not across the terminals. I've been able to operate the secondaries with a vacuum pump. The manual says there may be an open, but when I check for continuity from the terminal to ground, it's there.

Jeffvette

Bryan, shoot me a email I'm across the river in Washington. I'm busy for the next few nights but will have some time this weekend after tearing a 94 apart.

Hodos

Thanks for the offer, Jeffvette. It looks like I might be taking you up on that. I just don't understand what's going on right now.

How does this solenoid for the secondaries work? Given the term, I'm lead to believe either it's on or off. So, either I have a vacuum leak out the air port or the secondaries are open. I confirmed this by manually operating the solenoid. Is there some middle ground where the solenoid blocks vacuum entirely? I can't find much in the service manual on this.

Watching these sunny days pass me by is very depressing. I can count the number of them that we've had this year on one hand, if I forget about this week.

Jeffvette

The solenoid there is to act as the trigger for opening the secondaries. it receives the signal from the ECM to open up when certain parameters are met.

It then let's the vacuum out to open the secondary blades. Oncew the vacuum in the resevoir drops to a certain point, the vacuum pump in the front of the car picks up the slack.

I'll be over your way on Sunday if you want to meet up. Will be helping locobob with his starter, coilpacks and a few other items.

dallas916

Hmmmm....locobob has been pulling and replacing a lot of plenums lately. Sounds like a fetish to me.

Hodos

So, this is what I'm gathering so far. The switch is on the ground. Thus, there is always voltage to the terminal. Then when the computer says, "let's go!", it flips the switch and completes the ground. Secondaries are now opened by vacuum from the resevoir. In that aspect, my solenoid is working. When I manually ground the circuit
my secondaries open just fine.

However, when things are normal, instead of building up vacuum in the resevoir, it just goes out of the air port. This seems to be my issue. I have 2 solenoids that are doing the same thing, so I'm guessing it's not the solenoids' fault. If they are bad, then something is causing them to go bad.

There has two be positions on this damn thing. One blocks the inlet and the other blocks the air. I'm thinking in the normal position it blocks the inlet. This is probably spring operated with a plunger that seals the rest of the system (secondaries and air port) from the resevoir. I can only think that the spring is broken. I can hear the solenoid moving when I connect power to it. I'm about 5 seconds from breaking one open!!!

FYI - I'm mostly thinking out loud here...

The Lurker

Vacuum canister two way valve is bad most likely.

corvette1989bham

Could a "backfire" have caused the problem? LT5's backfire a lot causing vacuum leaks.

Hodos

How do I check this?

The Lurker

There are two vacuum lines that operate the secondaries, the one that initially forces a vacuum coming off the vacuum pump in the front right wheelwell. The other is the small line coming off the left side of the plenum. When a vacuum is applied to either line it should be able to remain with little loss. Since you know you vacuum pump runs all the time there is a problem. Remove the small line on the left side of the plenum and put you finger over it to seal it. If the pump stops then you know it's the check valve. If not then the problem is elsewhere.

Hodos

I broke down and tore into one of the solenoids. It was fairly straight forward. I was able to take out the spring, seal, plunger, and vacuum line. I cleaned it all up, hoping that maybe some debris got in there. It didn't help, so I put a small layer of silicone on the tip of the plunger (I let it dry before reassembly). It seals now and my vacuum leak is gone. I think it might be sealing a little too well, though, becuase the secondaries are having troubles opening. The SES light is gone now, so that's progress. I can rev past 3000 RPM as well. Yay for me!

I guess I'm going to order a new solenoid and see what happens. The engine did backfire when I first started it up a few months ago, so maybe that took care of the first solenoid. I don't remember any backfires after that, but who knows. Something happened to the second one, though.

The check valve seems to be working fine. Thanks for the help everyone.

415ZR1

I'm having a similar vacuum issue. Secondary won't hold vacuum, pump runs continuously. No codes. using a Mity-Vac hand pump, I've narrowed the leak to the solenoid. On the work bench, the solenoid will not hold vacuum when applied to either port with the other one blocked. Do hear air passing through the air filter on the back of the solenoid.

Have a new one on order...

jim barent

sorry i dont want to highjack the topic.
i have another probleem with the vacumpump.
mine was broke when i bought the car , i have repaired the pump en the vacumlines but now i have no current on the wiring to the pump.
does anybody what this is , al fuses are checked and okay
thanks

Hooked on Vettes

When the ignition switch is in run, 12 volts is applied to a 10 amp fuse and then goes to the vacuum pump motor.

The 10 amp fuse is located on the driver side plastic wheel well housing right below the front of the brake master cylinder. The fuse is inside a small black plastic cylinder shaped holder with a Orange and Blue wire going to it.

jim barent

aaaah perfect
never expected the vacumpump fuse in that place.
pump is up and running
thanks
jim

dallas916

ZR-1 people aren't just doctors....they are surgeons!