Non-operating Secondaries Repaired

[QB93Z]

Ever since I bought the yellow 1994 ZR-1 back in May, the engine at full throttle felt weak and "surged".

Using a Tech I, I determined that the secondaries would open and then shut again after a few seconds and a code 61 would be set. One of the causes of code 61 is when the secondary actuator solenoid is energized but secondary vacuum drops too low. When this happens the system shuts the secondaries.

I finally had time to pull the plenum and track down the problem and correct it. It turned out to be: 1 a vacuum leak in the secondary actuator vacuum system, 2 a bad secondary vacuum check valve, and, 3 a frozed vacuum pump.

The vacuum leak was caused by a replacement check valve (on the left below) somebody installed that had the inlet tubes too small to hold the rubber connectors:
http://i407.photobucket.com/albums/pp152/QB93Z/Misc/0625091724.jpg
I bought the replacement check valve at Advance Auto Parts for about $3.50. It is made by Dorman.


The vacuum pump appeared to have gotten wet inside (I pryed the cover off to see if it was repairable) and was frozen. I replaced the pump by ordering from Sport Chevrolet using the replacement part number I found here on the NetRegistry Forum (94669091). The pump is a prefect direct replacement for the OEM part:
http://i407.photobucket.com/albums/pp152/QB93Z/Misc/DSC02202.jpg

After putting everything back together, the secondaries seemed to work once, but then failed to stay open again. Trouble shooting with a vacuum gauge indicated a bad check valve.

So, another plenum pull to replace the brand new check valve.:confused:

Now everything works great. The car finally pulls hard like a ZR-1 should!:dancing :cheers:

Jim

[Jagdpanzer]

Well done Jim! and thanks for sharing.

[FU]

Tough fix. Glad to hear the car is running fine :wave:

[Scrrem]

Wow Jim....You are DA MAN!!!

Rich

[ZZZZZR1]

Wow Jim....You are DA MAN!!!

Rich

I agree.... :thumbsup:

[secondchance]

Good to know vacuum pump is still available.
Thanks.:thumbsup:

[Kb7tif]

Its pretty rewarding fixing this stuff isn't it.:thumbsup:

On mine I had a Bad throttle linkage.

[GOLDCYLON]

Great post up Jim. :thumbsup: How much was that pump. Maybe its time for a spare in the parts crib. GC

[QB93Z]

Great post up Jim. :thumbsup: How much was that pump. Maybe its time for a spare in the parts crib. GC

GC, The pump cost ~$140. I bought the pump from Sport Chevrolet in Silver Spring, MD. They have a great Parts Department there. John C. is one of the parts guys who spends a lot of time helping us track down parts. We also get a "club price" but I don't know how special the deals are.

BTW, My Quasar Blue 1993 was originally sold at Sport Chevrolet, so I feel like it is homecoming everytime I drive down there.:)

Jim

[tomtom72]

Nice fix, Jim!:thumbsup:

On that vac pump that went bad. Mine went bad also so I bought that pump and was going to have to cut the OE plug off to use the new pump. I took my pump apart as it had seized up solid, and the overload heated up the plastic plug enough to transfer plastic onto the spade terminals & still didn't blow the fuse!

Anyway, they are simple and mine fell victum to water thru the air intake. I used a long hose and added a filter and made a loop in the hose to trap water. I check it every month and so far no water. I think the filter, facing down, has done the trick. It's been about two seasons of use and so far so good. The motor responds well to contact cleaner and a rust penetrator and a toothbrush. I had to clean the grooves in the commutator as they really were packed with rust. They are repairable if you don't mind spending some time. To make it easier to work on the motor parts, I unsoldered the power leads to the brush block & the pressure switch. Just thought I'd throw this out there for anyone who might be curious.

:o sorry for the hi-jack Jim!

:cheers:
Tom

[Aurora40]

Good to know vacuum pump is still available.
Thanks.:thumbsup:

I don't believe a direct-replacement 1990 pump is still available? If I recall though you can splice the connector and use a later one, or take the guts out and put them in your original housing (as long as that's not part of the problem with your original).

I haven't done this, but recall hearing it.

[QB93Z]

Tom,

Not a hijack, this is a forum! :thumbsup:

I investigated my failed unit and decided not to attempt repair. Good for you that you were able to restore yours.

The 1990 vacuum pump has a different electrical connection than the one I bought using the part number above (94669091). I don't know if there is a source for the 1990 style vacuum pump.

Jim

[Jeffvette]

Tom,

Not a hijack, this is a forum! :thumbsup:

I investigated my failed unit and decided not to attempt repair. Good for you that you were able to restore yours.

The 1990 vacuum pump has a different electrical connection than the one I bought using the part number above (94669091). I don't know if there is a source for the 1990 style vacuum pump.

Jim


1990 Pump is different. It uses just bare spades for the electrical connector. Best solution is to cut off the pump connector harness and wire in the weatherpack connector that is for the 91-95 cars.

Jim, should have called me on the pump.

[ZR-1nce removed]

Wow Jim....You are DA MAN!!!

Rich


I agree Jim is Da man!

I'm sure he will post pics soon of the small project that he helped me with last week!

Darrin

[tomtom72]

Jim, thanks for not taking me the wrong way!

I'll try to restore yours if you want to send it to me ( or I can send my courrier service, ZR-1 Overnite ) to pick it up....for the next NCRS judging session...if you like.;)

:mrgreen: