The thing in the picture is a vacuum check valve.

One end goes to the rear of the plenum on the passenger side.

The other end tees off and one side goes to the cruise control. The other side goes inside the car to supply vacuum to move the heater/air control doors.

 

Well that would indeed explain why neither the cruise nor the vents work !

I followed the hose and one end is indeed connected to the thing in front of the front driver-side wheel (plenum?), and the other one just hangs loose. I'll try and find where it connects !

 

loony, the plenum to which we refer is the top of your engine, where the runners to the manifold attach. that is the source of your vac line.

what you refer to is the gas recovery cannister.

as I said in a previous post, one single vac line controls doors under the dash -vents- and cruise control, also gas (fumes) recovery. if that one vac line is open at the source, which is the tube in the plenum, it is a vac leak and affects engine performance, rough idle, for one.

 

Oh I see, sorry about the confusion, I'm still getting used to the technical terms...
I'll definitely take a look and check where it should be connected. (this car's a mess! :p)

 

The vacuum line going to the front of the car goes to the vacuum tank (the globular thing in front of the wheel well).

The vacuum check valve gets its vacuum from the plenum. The vacuum line connects to the side/bottom of the plenum on the passenger side. It's in front of the distributor. There are two vacuum connections there, side by side.

 

Thanks for all the info guys, it's really nice of you to take your time and explain all this

This is what I found on the fsm:


Uploaded with ImageShack.us

Should it be connected to where the second "hose" is written ?

I've taken a look earlier and found a small orange tube nearby that was connected to nothing so I hooked it up to the vacuum check valve but that probably wasn't it seeing as though.....the car refused to start afterwards it just cranked and cranked but refused to start so I assumed I was wrong. I'll continue looking.

As Joe suggested, I'll also take a look at the plugs, see if the gap is correct. These are NGK fr4gp plugs rated at a 0.035" gap; should I leave it at that ?

 

read post #65. he explained where the hose outlets from the plenum are located. you are on the wrong end of it. locate the SOURCE of vacuum before you worry about the connections to it. if you find the EGR valve and fuel pump regulator you will be close to the vac source(s).

the plugs are maybe ok, but I would have to verify.

I don't see any orange tube in your picture.

 

Alright, thanks for all this info. Won't be around the car for a week or two so I'll keep you informed of what I find !

 

to be deleted

 

Hey guys, just thought I'd share the final outcome of all this

My father took the car to an experienced Vette mecanic (who is far far away), because we couldn't seem to figure it out ourselves.

It turns out that the timing had been indeed been messed up, but corrected thanks to all of you. The second thing wrong was really, really dumb, and I felt like an *** when he told me where it all came from: the first mechanic had mixed up two wires :X I thought I had indeed seen something wrong but when I had tried correcting it the car ran worse !

I'm getting the car back on saturday, can't wait to drive it like I used to ^^

The mecanic mentioned something else: he said the car had a little blue smoke in the exhaust, and that the valve cover joints (I'm not sure about the translation) were probably starting to wear out (and incidently that it cost about 3 grand to fix it...so he recommended just checking the oil now and then :p)

Thank you all for your precious help, I really appreciate all of what you did to help us out !

 

Sounds like valve stem seals. Nowhere near $3K.

 

But doesn't it imply cracking open the block to replace those ?

 

Just valve covers, rockers and valve springs.

 

Oh okay, good to know

 

The hard way to do this is to remove the heads. The easy way is to do it with the heads on the engine, which is obviously way cheaper.

To replace the valve stem seals you need a tool to compress the valve springs and a tool to hold the valves in position while you're doing that.

There are two types of valve spring compressors. One is a lever that attaches to the rocker stud and presses down on the spring retainer. The second type clamps on to the spring and screws down to put pressure on the spring retainer. The idea is to allow the keepers to be removed from the valve stem.

There is a tool that pressurizes the combustion chamber by screwing into the spark plug hole. You apply air with an air compressor to hold the valve in place while removing the keepers from the valve stem. I have also heard of stuffing rope into the combustion chamber to hold the valves, but that technique seems pretty iffy to me.

When I did mine I turned the engine over until the piston was at TDC for the cylinder I was working on. That way there is no possibility that the valve can drop into the cylinder.

There are two types of valve stem seals. Basically it boils down to the cheapies vs. the good guys. As I recall they were neoprene vs. teflon (I don't remember for sure). The price will tell you which ones to get...

 

Thanks for all of the info, it sure seems like a hard job !
I hope it doesn't come to this...

 

Naw, I've done the "rope trick" a few times with out a hitch. Just make sure the piston is at TDC.

 

does this tac wire have to be disconnected in order to adjust the timing,,positively?

 

Absolutely yes. The EST wire advances the timing from computer instructions so in order to set base timing it HAS to be disconnected.

 

And when that kid kicked the front bumper with the GTO Ferrari in reverse gear trying to get the mileage odometer down too........
I wish my 90 coupe odometer would display, along with the digital speedo & gas gauge... lol...is it a difficult job to remove the instrument cluster ...to get rebuilt...and where...thx....the tach reads high & pegs out tooo early...thx