quote:

QUOTE FROM ANOTHER FORUM I'M ON - Not by me
This is long... but It will explain alot of things:

I have been on this board for a while, and have found many people that have a CPI system that is breaking and they have to replace it. For those of you that don't know the CPI system was used on engines from about 92-95. And is trademarked by a plenum cover that says "vortec" in orange and an intake that starts from the front left headlight. I have a 94 s-10 blazer and my cpi broke and i replaced it myself.

The CPI Unit is located inside the upper intake plenum. It consists of the cpi which is connected (integrated) into the fuel pressure regulator. To see the system, you must take off the upper plenum. The unit is located in the center of the intake, with 6 poppet lines/nozzles branching off of it.

There is 2 things that tend to break with this system over time. They are

1. Fuel pressure regulator: this is the most common thing that breaks. There is a diaphram inside the fuel pressure regulator that breaks and will leak gas into the plenum. The fuel pressure regulator is in the center of the intake on the passenger side. It looks like a gold cylinder.

2. Inlet/Return fuel lines: There are 2 fuel lines that connect to the cpi unit. They are on the drivers side. They will weaken over time and can get pinsize holes in them that will leak gas into the intake.

Common systems of these failing are: Bad idle, hard to start, shaky revs, low gas mileage, and most important i think is bad smell from the exhaust.

The best way to check for a failure is to remove the upper plenum. The plenum is the huge piece under the "vortec" plastic peice. Looks like 3 tubes going down on each side. There are about 9 or 10 bolts that you need to take out and also remove electrical things, etc. to get it off. I would suggest buying a haynes manual or chiltons manual. They explain it well. I am not a mechanical expert, and i DID this myself. It really isnt that hard if you take your time. Shouldnt take more than 30 mintues or so the first time.

If you do this, and get the intake off, look at it from the front. If 1 side of the intake appears clean, this will be where the leak is comming from. If it is passenger side, it is probably the fuel pressure regulator, if it is on the drivers side, it is probably the fuel lines.

*SORRY DEAD PHOTO LINK*

This is my intake above. As you can see the fuel pressure regulator has leaked and fuel has got into the intake and cleaned it, thats why it appears goldish. If no fuel has leaked, it should look all grimy, like the drivers' side in the picture.

There is also other ways to check for a leak, but arent as effective. One way is to disconnect the brake booster line and smell for gas. It comes out the back of the plenum and goes to the brake booster at the back right of the engine on the firewall, (if looking from the front.)

It is very easy to replace the CPI unit and fuel return lines. I don't really want to go into details, but if you need help, email me.

I would suggest buying your parts at [url]www.gmpartszone.com[/url]m, they have the best prices i found, and are very helpful. I wouldn't suggest gmpartsdirect.com. I orderd from them, and it was taking forever so i canceled, and they have horrible customer support.

The CPI unit gm part # is 17113673.
The fuel lines, called a "nut kit" are # 17112705
Prices are about $272, and $40 respectively.

If you want to go to the dealer, expect to pay $473, and $63. I've checked. If you want them to do the install, expect $700-900+. Rip off.

Its not hard to do it yourself, and i would strongly suggest doing it. I did mine for about $350 total (and i had the parts overnighted). Just need a socket set, screwdrivers, etc. Basic tools.

quote:

ORIGINAL: swartlkk

There isn't any other way for fuel to get into the engine other than through those lines.