Just got thru rebuilding my TPI and installing new injectors this past week while I was home. Found one issue though that I cant solve. I have a vacuum line missing... It is the one that is in the rear of the mount that the coil mounts above. The front side has two male ends that run to the TB and EGR valve. When I got it all back together and was remounting the coil I noticed there was not a line on the back of the splitter. I had two barbed retainers on either side of the vacuum nipple like they were to hold a thicker rubber line instead of the little plastic lines. Any help and I would appreciate it, I gotta go back to Afghanistan on Tuesday and would really like to solve this prior to then! Thanks in advance! Oh yeah, 88 IROC 5.7 L98 with auto if that helps....

Picture would be worth a thousand words here, but let me take a wild shot in the dark....

The EGR valve vacuum solenoid has 2 vacuum lines going to it but 3 vacuum nipples. One line to the TB, one line to the EGR valve and a 3rd vacuum nipple that connects to nothing (the vacuum "bleed" port). Originally they had a little foam filter over them but that's usually long gone.

If this line up with what you are seeing then everything is normal- there is no vacuum line supposed to attach to that 3rd port. It's just supposed to be open to the air.

Go down and read my thread. it contains 2 different vacuum diagrams. the thread is called " (TPI OWNERS, I need a little help please. Hoses and lines issues.)TPI OWNERS, I need a little help please. Hoses and lines issues. " I had the same issues too. Does it help?

Damon is correct.

Here is a pic of my 86 IROC-Z EGR solenoid. It only has 2 vacuum lines. One goes to the EGR Valve and the other to the T connection that also connects to the little male nipple under that throttle body which also connects to the Cannister. Does this help? look at my thread and there are 2 diagrams of vacuum routes.

I had read your thread earlier but it didnt show the piece that I was referring to. One of the mods posted a really good pic but it didnt show the rear vacuum line.

I learned on the vette forum to always take plenty of good pics and usually keep a digital camera handy for when my memory runs low but I didnt have it out there with me. I didnt remember disconnecting this line when I was tearing it down but the mice had gotten a pretty good hold under the hood a couple of years ago and caused me a lot of headache so I thought this was something missing since then. Here is a pic I went out and took a little while ago after I got Damon's reply. It has a red vacuum cap on the nipple in the pic. I removed it shortly after the pic. So now its free to breathe... I still have a vacuum leak somewhere as it still idles up and down but at least its running a lot smoother.

One last tip, dont store your car with 10% ethanol gas... ask me why.....


Thanks for the help from everyone.

I tried to go back and edit the post but it wouldnt let me. Its the red cap in the center. you are looking at it from just above where the coil would normally be mounted. Its on the lower end of the bracket that hooks up beneath the coil. Towards the front of the engine are the two male ends that run to the TB and EGR. Again, many thanks!!!!!

I got 2 pictures of the part that you are referring to just above your latest post. Y should I not store with 10% ethenol?

yup thats your EGR solenoid. it doesnt need that little red cap.

Ill be right back in a jiffy, maby later. I got to help the wifey cook food. C ya in a little. My wife is treating me like this .

I dropped the tank in the IROC in October and installed a new fuel pump. Cleaned the tank and refilled with 93 octane. Had 10% ethanol on the pump. Added Stabil fuel stabilizer. Almost filled up a two liter Coke bottle with mule pee and water before the gas started going to the engine again last week. Luckily I had checked it prior to installing the new injectors.

Installed a new fuel tank on my 78 vette in November. Same thing, same results.

Boat was filled drained and refueled also in November for prep for storage. 3 days on the lake working on a new boat engine to get all the water out. I am trying the Marine Stabil this time to see if it will solve the problem. The ethanol attracts moisture from the air. My cars are kept inside out of the rain.

That sucks. Did you figure out the vauum lines?