1990 Celica GTS Cold Start Problem

[Bossard]

My Celica has a 5S-FE engine. As soon as it goes down to say 60 degrees or below it really is hard to start. The colder it gets the harder it is to start progressively. I think it is the cold start injector or cold start injector time switch not working because if I spray a small burst of starting fluid into the throttle housing through the butterfly plate it kicks right off. There is a relay block in the engine compartment with a lid with markings. One of the markings says fuel and there is no fuse or connector plugged in where that fuel marking indicates inside. I wonder what this is for. My other Celica with the same engine has a two pronged copper connector where this one has none. Does anyone know if that could be the connection for the completed circuit for the cold start injector time switch?

[93celicaconv]

Old post, but did you ever get your questions answered?

I have a 90 Celica w/the 4A-FE, and 91 Celica w/the 4A-FE, and a 93 Celica with the 5S-FE. Only the 90 has a cold start injector system. Is it possible Toyota eliminated this method to improve cold startability after 1990?

Anyway, my 90 Celica had the same problem. I got copies from a service manual from a Toyota dealer to help diagnose the problem. My testing indicated the cold start injector time switch was bad. I found a used one in a salvage yard, put that in, and the problem was resolved.

If you still have this problem, there are some simple test procedures you can do to determine if the injector itself is bad, or the switch. Let me know if you still have this problem.

[Bossard]

Yes I still have the problem. I am glad you asked!

[93celicaconv]

These are the steps I would take to figure out if your cold start injection process is working properly or not.

First, check if the cold start injector time switch is working. Disconnect the pigtail from the cold start injector time switch. There are two electrical prongs in the cold start injector time switch. Using an ohm meter, check the resistance across these two prongs. Resistance should be between 20-40 Ω with coolant below 86°F, or between 40-60 Ω with coolant above 104°F. If the resistance is not within these ranges, replace the switch. If OK, reconnect the wiring pigtail.

Second, if the switch tests good, check the wiring harness. Engine must be cold. Disconnect the wiring pigtail from the cold start injector. With a 12VDC continuity tester (light), from the wiring pigtail, connect one lead of the 12VDC continuity tester to the pigtail "NOT" involving the black (ground) wire, then connect the other lead of the 12VDC continuity tester to ground on the engine. The light should be out. From the driver’s seat, make sure you have clear visibility to the 12VDC continuity tester light (or have a 2nd person watch it). Turn the ignition key past the run position, to the position just shy of turning the engine over (if it turns over, that is fine too). The light should come on and stay on until the key is released. If this works, then the wiring harness and the cold start injector time switch are all functioning; reconnect the wiring pigtail. If this doesn’t work, but the cold start injector time switch tested good, you have a problem in the wiring harness.

Third, to check the cold start injector, disconnect the wiring pigtail. If you are fortunate to have a short piece of a 2nd wiring pigtail for the cold start injector from a salvage yard, with 6” or more of wiring, this will help a lot. Plug the 6” long wiring pigtail into the cold start injector. Ground one wiring lead to an engine or chassis ground. Connect the other wiring lead to the +12V terminal of the battery. You should hear a click sound. Try this repeatedly to ensure you are hearing a clicking sound. If you do, the cold start injector solenoid is working. If you don’t, replace the cold start injector. If you hear the clicking sound, hold the 2nd wire to the +12V terminal of the battery (solenoid should open the injector), then have a second person try starting the engine. As soon as the engine starts, remove the wire from the +12V terminal of the battery. The engine should have started quickly & smoothly. If it did not, then the injector itself may be plugged. Replace the cold start injector.

Hope this helps. If you have a salvage yard around that has a number of early 90’s Toyota’s in it, you should be able to find a couple of used parts, once you determine what you need.

[christine_lives!]

Seems silly to ask, but have you ever had your battery and alternator tested? If your battery isn't holding enough charge, it'll make cold starting a real pain in the ass.

I'd also look for cracks in vacuum hoses. Any leaking air attached to the intake manifold will also make starting a pain in the ass.