1988 2.8 Manual
A few weeks back my 88 cruise stopped working. No big deal – right?
Most of the time it’s the switches at the peddles that get out of adjustment. So the other day I thought I would fix the problem and go for a spirited spin to check it out. I did so with no luck but I did enjoyed the drive any way. Got home and stated to dig a little deeper. Pulled both switches off the peddles and opened them up. Easy to do because the covers on the switches just snap on. Could see nothing wrong but got my meter out and they both checked out OK. Next I went back to the Vacuum Servo to see if everything looked OK back there. Noticed that allot of the hoses were not in the best shape. Replaces them and off for another drive. No luck on this fix also. This is not my first Fiero and on my 87 I had the stalk go bad so of course I was pointed at that. Pulled it from the Colum and pulled a heavy string along with the plug for ease of installation once checked out. Got it on the bench and sure enough 2 of the wires did not have continuity. Replaced the wires and all checked out fine. Put the switch back in the car and around the block I go. Again the cruise was not functional. The next thing I checked was the vacuum release switch. This sits below the Vacuum Servo with the red connector. Pulled it out and got my battery charger out. Connected a couple of test leads to the charger, plugged it in and tested the switch. Engaged it held vacuum fine so back in the car it went. All this time I have been referring back to Oliver Scholz
http://www.fieros.de/en/main.html article on his web page that I found a great source. Anyway, the next thing I checked was the vacuum, or as I found out, the lack of it. No vacuum at the servo ??? The vacuum is drawn from the plenum. It’s the fitting on the plenum next to the distributor. Started the car and pulled the hose off to find plenty of vacuum. Traced this hose over next to the PCV valve. There 2 rubber hoses that come from the right of the plenum and cross over to the trunk wall. There they attach to metal lines that run the length of the trunk wall over under the servo and to the fuel tank evaporation tank. That’s the black plastic can next to the air cleaner. The small metal line is the one that carries the vacuum over to the Vacuum Servo. This line has 3 openings. The end from the Plenum, the one for the servo the end that goes to the fuel tank evaporation tank. So I plugged the servo opening, undid the line coming form the plenum and attached a clean rubber hose to end that goes to the fuel tank evaporation tank. Put the hose in my mouth and could not blow thru the line? This would mean that the metal vacuum line was blocked. Never heard of that but sprayed some WD40 down the line and let it sit during lunch. After lunch a used compressed air and blew the line out in the opposite direction of the vacuum. Sure enough, crud came out the other end and the line was now open. Plugged all the lines back to the correct configuration and off I went around the block again. This time the cruise worked great. I have worked on allot of cars thru the years but have never seen a metal vacuum line clog before. Must have been carbine that built up in the line is all I can think of. Hope this helps other sometime down the line.
