No or low spark #4 and #7 plugs

[secondchance]

Originally Posted by DTZ ZR1

I will be changing out the injectors, I believe that they are stock. It does not look like anyone had the plenum off. The factory plug wires are still on. I figured on changing the packs and wires too and anything else that might be bad.

Jerry's gaskets come in two different thickness, Which would be better?

I am trying to clear my schedule so I can start on it this weekend. I do not think I could wait three weeks to drive her again.

It may be wise to have a couple of vacuum check valves and also make note of which hole plenum bolts was removed from and clean the bolt threads before reinstalling them. It's pretty easy to strip the threads in the injector housing.

I replaced all 16 injectors 3 months ago and the result was astounding!

[Z51JEFF]

Originally Posted by Jeffvette

His car does not have that as the EVAP system is in the front of the car.

.........................................Never mind

[DTZ ZR1]

Thanks for the info, I will be careful with the bolts.


DT

[tomtom72]

DT, I have a 90 so I would like to pass this possibility on to you as a fwiw. This relates to the fuel lines and block at the right rear of the plenum. The two fuel lines that come up from the frame go to a block w/ two T45 torx bolts. That block is the start of the under plenum fuel rail system.

On my car the lines at this block were in the way of me getting the Torx bit squarely on the last plenum bolt. Bleed the pressure off, and loosen the two t-45's on the block enough so you can swivel the lines enough to get on that plenum bolt squarely. You could just remove the two lines from the block if you like. Either way, the lines maybe in the way of the last plenum bolt. I don't know if it is just my car, it could be. Just thought I'd mention this as a caution.


Tom

[jonszr1]

have the same issue on both my 90 and 92. i just pull the fuel fitting and be done with it .

[ZR1Vette]

There is no way to get to the last torx bolt for the plenum without moving the fuel rail feed line... I would strongly recommend removing (not just 'moving') entirely (very easy to do). If you bung up the fuel line they are NLA and are rare as hens' teeth.... I know...my feed line had a defect and was lucky to get one from Kurt White.
Here you can see the line disconnected and just sitting in place and the torx bolt clearly accessible... also shows the extrusion defect (red arrow) which allowed fuel to seep thru the line and drip onto engine>>>

Originally Posted by ZR1Vette

There is no way to get to the last torx bolt for the plenum without moving the fuel rail feed line...

Michael, every car is different. Some you have to remove the pipe or at least undo the screw a little bit. Other cars you don't. If you do remove it check the o-ring as they are always destroyed. Also make sure you have bled pressure out of the rail, either by using the schrader valve or letting the car sit for a long period of time.

[DTZ ZR1]

Brothers, I have taken the Plenum off, it took about 2.0 hours. I had some help from my 10 year old son and 12 year old daughter. I am trying to get them interested in cars. Daughter loves Vettes and son likes Mustangs, enough of that.

Tom, I did remove the fuel lines, made things easier.

The ignition module plugs were interesting to say the least, can not wait until I put them back on.

I do have a question, how can I tell if I have the original injectors? I attached some pics for you all to look at and see if there is anything else I need to check. I was really wondering about the secondary actuators.

To remove the injectors do I need to remove the fuel press regulator? I am going to remove the coil packs bracket and all for cleaning purposes. What about the crank case vent valve cover, should I remove that too?

Again, thanks for all the info.

DT
[ATTACH]Zr1Plenum 027.jpg[/ATTACH]

Zr1Plenum 023.jpg

Originally Posted by DTZ ZR1

Brothers, I have taken the Plenum off, it took about 2.0 hours. I had some help from my 10 year old son and 12 year old daughter. I am trying to get them interested in cars. Daughter loves Vettes and son likes Mustangs, enough of that.

Tom, I did remove the fuel lines, made things easier.

The ignition module plugs were interesting to say the least, can not wait until I put them back on.

I do have a question, how can I tell if I have the original injectors? I attached some pics for you all to look at and see if there is anything else I need to check. I was really wondering about the secondary actuators.

To remove the injectors do I need to remove the fuel press regulator? I am going to remove the coil packs bracket and all for cleaning purposes. What about the crank case vent valve cover, should I remove that too?

Again, thanks for all the info.

DT

DT, to remove the injectors, just remove the fuel lines going into the junction block and then undo the 4 mounting bolts going into the injector housing. Then pry up.

You probably should remove the coil pack grounding plane and the starter as I can see the crap in the V of the block. You need to clean everything around the breather box before removing it, then find a solvent tank or just use brake kleen on the breather box itself. You'll have to remove the secondary linkage to get the breather box out.

The injectors are originals.

[tomtom72]

DT, looks like mine when I pulled the plenum. What a mess I had from loose cover bolts. Listen to Jeff.

AutoZone, I guess any parts store, sells the hard vac line in small spools along with the connectors so you can actually make a new vacuum spyder if you feel the need. The stuff bends & can be shaped with a hair dryer.

I'd r&r the wires and coils. The box cover bolts are proly finger tight like mine were. All the mess was in my valley and my baffle box was clean, oh, the cover hoses maybe all hard and some where here is a thread about which radiator hose to use to make them. I used 19 lbs for them going back in with an circle pattern. Don't know if that was right, but mine hasn't leaked since.

Test the actuators, they should either start to open at 8" Hg(?) and fully open by 12" Hg(?), and the movement should be smooth & linear. Yours look like mine did, I think they are in upside down which is okay if they still hold vacuum and have smooth movement leave them in that position as the diaphrams have taken a "set"....which you don't want to mess with....or you can buy new ones, but they need to be tested as the springs on some were installed wrong and they don't move freely if installed correctly. Sometimes you have to put them in upside down to get them to work smoothly.

Not to spend your money, but I would r&r all the injectors at this time, JMHO. Don't forget to check all the ground connections at the back of the block. You can see them easily now. Get a tube of dielectric grease and some star washers, and r&r the grounds, clean them & use the Di-electric and a star washer going back. The grease works well to service the rubber gaskets on all the electrical connectors and a dab in the pins is good also before plugging them back together.

Another caution: if you take apart the horn from the T/B for cleaning reasons....Do Not Use Carb Cleaner! Use Throttle Body Cleaner Only in the T/B. You do not want to ruin the DAG inside the T/B as it seals the butterflys against the T/B bores to close off stray air bleeding so the IAC can do it's job. Oh, and clean the IAC pintle & bore too. Don't be alarmed at the amount of liquid oil in the intake tract, that's sop for an LT5. Catch can is a good addition for that situation.

You're doing well, and the helpers are a great crew!


Tom