how con you tell if the thermo time switch is faulty on 78 280z


Asked by Jul 21, 2013 at 02:09 PM about the 1978 Datsun 280Z

Question type: Maintenance & Repair

car is running rich

4 Answers


I have an 80 280zx and my thermotime switch is broken. I've replaced the fpr and the csv and she'll crank after sitting for a while (like a day). But she dies if I let her drop below 700 rpms and hitting the gas does not matter. She will not rev back up if she drops that low. It may be different for a 280z vs a zx, but I've gone through every single possible cause and I keep coming back to my thermotime switch. The ECU isn't getting a reading from the switch which is causing my car to run rich but then die. She runs rich because the ECU believes that the car is cold, so it gives it extra fuel. Then, (I believe) she floods out. I don't know if this answers your question, but I've found that it's sometimes better to have someone in a similar boat offering their two cents. :) Good luck!

1 of 1 people found this helpful.

The ECU doesnt adjust the mixture via the themo time switch. You can delete it and affect nothing but cold start ease. I took mine out a long time ago along with the extra injector and the car runs and starts great. The thermotime switch merely turns on the extra injector when the temps are cold. The ECU reads temperature and adjusts mixture from the water temp sensor. I would check fuel pressure, fuel filter, ignition, timing.

3 of 3 people found this helpful.

i replaced the distributor and it cleared up the rich running and hard starts


On the drivers side by the foot rest there is a box [Electronic Control Unit]. You can detach from that the 35 pin connector to check the continuety of your connectors and harness. Everything from your Air Flow Meter to your thermotime switch. Down load the shop manual for which pins to check. GaZet- 30yr member -Ga Z car Club

2 of 2 people found this helpful.

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