temperature gauge

[bobby5555]

Wondering if anyone has ever had this happen , on my 1981 spider . Last summer my engine would start running ruff if I drove under 40kph (25mph) for more than 10 min. Get to 80 kph and after a couple minutes all good. The engine was over heating due to a bad thermostat but the temp gauge never went over 190 so at first I wasn't sure what was happening. Any ideas why my gauge did not show the correct temp over 190. Is it possible the gauge never went over 190 in its life and now there is something holding it back from going over 190.
Thanks from a new member. Bob

[18Fiatsandcounting]

Bob, several possibilities come to mind, but first, a question: When you say the car was overheating, what do you mean? Radiator boiling over through the radiator cap? Steam coming out of the coolant reservoir on the passenger side? Or ???

-Bryan

[bobby5555]

Luckily no steam or anything like that. It just started running ruff as in no power and that smell when a engine get too hot. I realized the thermostat was bad when I touched the bottom of the rad and it was cold. Yesterday I grounded the wire going to front temp sensor to see if the gauge would max out and it did so I guess the gauge is not stuck. That temperature sensor switch must be bad. Still baffled why the gauge did not go past 190 when it clearly was overheated. Thanks

[ORFORD2004]

Still baffled why the gauge did not go past 190 when it clearly was overheated

Air in the system

[18Fiatsandcounting]

I'm assuming your '81 spider is fuel injected? If you truly do have cooling system issues (which it sounds like you do), then the temperature sensor for the ECU could be feeding "bad data" to the ECU and so your air/fuel mixture is way off, resulting in low power. The temperature sensor for the ECU is the one at the coolant outlet neck next to the radiator with a 2 pin plug.

Air in the system as Orford mentioned above, or a stuck thermostat (or installed the wrong way), or blocked radiator, etc.

-Bryan

[bobby5555]

Yes it is fuel injected, I think the problem was air in the system , The thermostat was bad and I have since installed a new one and added a filler t on the heating pipe. While refilling I jacked the front way up and squeezed the pipes. I think I got all the air out now. Our nice weather has since changed back to snow so I can't take her for a good run to see for sure. Thanks