1980 Fi runs really rich

[forzaphil]

I think you're right Chris. I will order a new Coolant temp sensor and throw it in there. I think I have read that i will need to burp the coolant system in order to remove the air that will inevitably enter when I change the sensor. If anyone else has any suggestions for things to remember feel free to shoot them my way. I will report back once I have done this. Thank you to everyone that has been so willing to offer advice. This forum rocks!

I hope soon to once again be taking afternoon trips such as this...

[meangreenspider]

Did you ever figure out the problem? I am having very similar symptoms but car seems to run fairly well at operating temperature except for backfire when downshifting. It seems there is a lot of unburned fuel. At cold start engine idles fine but sputters and blows blue smoke out exhaust as rpms increase. After a short time car seems to run ok. I pulled a plug today and it was very black, plugs have 1500 miles on them. Any ideas?

[forzaphil]

Definitely! I had started a couple threads related to my problem and must have not put the answer to my struggles on all of them (after a year of troubleshooting i got a little disorganized...)

The culprit to my problem ended up being the Fuel Pressure Regulator on the fuel rail near the injectors. I had checked it with a pressure gauge and it seemed to check out (35 PSI at idle) and appeared to do its job; as I opened the throttle it would raise the fuel pressure slightly, So i figured it was in working order. What i didn't realize is that when i would open the throttle pretty wide (when my problems would begin) the valve within the fuel pressure regulator would stick somehow, and basically block off the fuel return line completely, causing the fuel pressure to rise and rise and rise. When the mechanic finally stumbled upon the problem, his gauge was PEGGED AT 100 PSI.

A simple way that i learned to look at it, (in retrospect obviously ) was to monitor fuel pressure and spark at the plugs WHEN THE PROBLEM EXHIBITS ITSELF (I felt like such a dumb for monitoring fuel pressure without actually having recreated the problem) Figure out a way to hook up a cheap timing light where you can see it as you drive, as well as a fuel pressure gauge. If one starts to act funny, it will show up there.

However, if your problem is temperature related, (as in, once the car heats up the problem goes away) then i would point you to the Coolant Temperature sensor located in the coolant tee at the front of the block. Otherwise, check the resistances of your AFM. If you need help figuring out how to check those, go to Bradley Artigue's Website. The coolest PDF you will ever read in my opinion.

http://www.artigue.com/fiatcontent/book ... 124_MM.pdf The fuel injection section starts on page 38, but all of it is really interesting.

Have you started your own topic? There are a ton of really knowledgeable people on this forum. Long Response, I know...

[meangreenspider]

thanks, I appreciate the very quick response.