Worth mentioning for you fuel injected owners

[Turbofiat124]

This maybe common knowledge but thought I'd mention it in case this happens to anyone else and to save you some time. I've been chasing a re-occurring problem for like three or four years and thought I had it fixed but apparently not.

Knock on wood, I think the problem has been corrected.

That coolant temperature sensor that goes to the fuel injection system on my 1980 Spider has given me a fit more than a few times since I've owned this car. It's mounted in a vulnerable location. It's not really the sensor itself but the connector. It's hard to tell with the hood closed but it comes close to the hood and I've wondered if that has anything to do with it. I've replaced the connector twice I know of. Also coolant can leak onto it and corrode the connectors and send a fake signal to the ECU.

I can't remember the exact order but here are some things I've encountered.

The sensor itself was leaking between the brass and plastic. This caused the engine to start overheating at red lights and once the car started moving, it would not cool back down. I found it by wrapping one of those blue shop rags around the sensor and seen where it was soaked. So I replaced the sensor.

A couple of years ago I was chasing down this misfire that would come and go. They always say, "check the ignition first". Well I did. I replaced several ignition components and even swapped distributors from a spare engine. Then I discovered that with the hood up, the car would idle fine but with the hood shut, it would misfire and blow black smoke.

I finally discovered this:

https://drive.google.com/file/d/1d9dvaI ... sp=sharing

So after replacing the connector, I thought I had the problem licked. Not so fast!

Then the car got to where every now and then it would just stall at idle for no apparent reason. Usually within a couple of seconds after starting the engine. It also got to where it would may take 10 seconds of cranking before the car would start. The car wouldn't stall going down the road but didn't seem to run all that smooth at times.

I thought it was water in my fuel from where the car sat over the winter. But seems like "bad gas" seldom turns out to the be case.

I considered the ignition switch going bad.

So the other day it was suggested to check the coolant temp sensor. Well I just replaced it along with the connector a couple of years ago. As I was wiggling the connector, I found I could make the car either stall or idle rough. As hard as these connectors are to get on because they are designed to make a tight fitting, the replacement connector does not fit as tight. But when checked against an old Bosch sensor, it's tight so it must be the replacement sensor.

Somehow it was "plugged in" but was not making perfect contact causing an intermittent connection.

Apparently I did not have the connector plugged in all the way. My guess is the sideways rocking motion of the engine while turning the engine over was what was causing it to be hard to start. If this sensor does not get a good reading, it will cause the engine to run too rich. So the rich mixture was probably what was causing the engine to stall and hard to start.

Symptoms I've encountered from this bad connector:

1) Won't start (mixture too rich)
2) Starts and idles but blows black smoke out exhaust and fouls spark plugs
3) poor fuel economy
3) doesn't run smooth or low power
4) hard to start or stalls for no apparent reason

Coolant can drip onto the sensor causing a higher resistance sending a false reading to the ECU.
Wires could be almost broken causing an intermittent issue. Such as in my case.

A friend said he relocated the sensor to the cylinder head in place of the overheat switch by modifying the overheat switch. This is on my "to-do" list. Here is yet another option. I ordered one of these adapters. The 1/8" NPT threaded hole will still have to be drilled and taped for a 12 X 1.5 fitting but might be easier than modifying the overheat switch.

https://www.ebay.com/itm/Oil-Pressure-S ... 2749.l2649

[Jon124]

This is good info, thanks.
You mention the potential interference between the coolant temp sensor and the hood, so I’m wondering if your sensor is installed incorrectly? The temp sensor is supposed to be on the bottom side of the coolant T, and the bleed plug on the top. When I got my car it was as you describe with the sensor on top, and also had a broken connector. When I was fixing this I discovered the PO actually installed the coolant T upside down so the restricted port was towards the radiator instead of thermostat, causing the engine to always run hot.

[Turbofiat124]

This is good info, thanks.
You mention the potential interference between the coolant temp sensor and the hood, so I’m wondering if your sensor is installed incorrectly? The temp sensor is supposed to be on the bottom side of the coolant T, and the bleed plug on the top. When I got my car it was as you describe with the sensor on top, and also had a broken connector. When I was fixing this I discovered the PO actually installed the coolant T upside down so the restricted port was towards the radiator instead of thermostat, causing the engine to always run hot.

No, it's installed with the sensor on the bottom of the coolant tee. I just wonder if the wiring somehow touches the underside of the hood and the constant rubbing back and fourth chaps the wires over time.

Someone posted how the wiring is supposed to be secured and routed to prevent this but I can't see to find it. Seems like it goes through a metal band that goes underneath one of the timing cover nuts.