Had a no spark problem with our 85 camry. Diagnosed around several potential problems, finally replaced the ECM. Bought ECM from online vendor with a warranty. New ECM restored spark and finally started car. Had to turn over for a long period and finally got to start by priming into the intake manifold. Thinking we had a fuel delivery problem, tried cleaner for injectors, changed fuel filter, but car continued to be hard to start, particularly after sitting overnight, etc. starts well after running. When starting, turns over endlessly until finally fires once or twice and then starts and runs ok.
Took car to toyota mech and he advised cold start citcuit in the ECM was not functioning. Have now acquired another ECM as a warranty replacement - same result. Car won't start when cold. Looking into the wires to the cold start injector, where do these wires come from. Tried to check continuity of same colored wires found behind the glovebox, don't get ohm readings that make sense when wires are not connected. Any clues what else to check or how to trace the wires to the cold start injector?

 

Cold start injector consists of the injector and injector timer. The injector timer body is plumbed into the engines coolant system exit manifold. The timer operates when the coolant is below a certain temp.

The injector receives 12v DC power by being wired to the starter motor wiring circuit that powers the starter solenoid relay coil (small black wire connected to solenoid).

The ground connection of the injector (green wire) runs to one terminal of the injector timer. When the timer is running the green wire is grounded to complete the injector circuit allowing it to operate.

A separate wire (black for auto trans or black/white for manual) connects to the same starter motor circuit running to another terminal on the injector timer. 12v DC power to this wire activates the timer.

The timer has a common ground path for both circuits via the timer body.

The above circuit is NOT connected to the engine computer in any way, totally independent. Operation is based on coolant temp and 12v DC power going to the starter solenoid coil when ign key turned to start.

 

We bought the car a couple of years ago, it "came with" a jumper wire to activate the starter because apparently the switch does not always engage the starter. With the key on, the jumper wire will start the car; however what you describe seems to indicate the problems are likely related. I wonder if the cold start injector could be bad, but if it were the only problem, seems priming would work better than it does. Is it common for the key switch to go bad? Any ideas on the most likely cause?

 

A mechanic told me the cold start side of the ecm was not functioning, but if cold start is not related to the computer then was he feeding me a line or what?

 

The injector and injector timer receive DC power when the starter motor is engaged and the coolant temp is below approx 95F.

The issue could be the injector, timer or wiring. There is only one injector for cold start operation. This injector is separate from the fuel injector each cylinder has.

Can not speak for the mechanic opinions. The cold start injector was eventually replaced by using the individual cylinder injectors whose injector timing was varied for cold start operation by the ECM.

The injector would be on the intake manifold.

 

We have located the injector and tested it, seems to work ok. The mechanic took another look at the car and advised the cold start injector timer was bad, so we have replaced it; not with a new but one from another camry (86) also had a spare from the junk yard. The spare seems to make a difference although still hard to start. Will try to clean the injector or see how it fares over the next few days. He also advised the igniter was bad, the car does start and run, so could the igniter be bad? I expect if it were bad or intermittent there would be times of other problems, dying etc?
We also have a problem with the starter, occasionally it will not engage but only click, as I am aware this is an indication of low battery or bad starter solenoid; however, we traded the starter onthe other car and still the 85 occasionally only clicks. It makes me wonder if the cold start problem could be related, since you indicated the start circuit provides the power for the cold start injecter? We disassembled the battery terminals today and found no problems so cleaned and reassembled. Any other ideas?

 

Igniters typically work or they don't. There is no way to test them.

Had starting can also be caused by general ign issues such as bad distributor cap, rotor, plugs, ign coil.

As to the clicking.

Sometimes the battery cable terminal end connections to the cables can start to fail.

Or the battery cable between the battery and starter solenoid can increase in ohm resistance causing lack of available current at the starter solenoid connection.

Or a bad battery ground cable or connection to the chassis.

If you have jumper cables, when the clicking occurs use a cable to start bypassing the large battery cables such as cable between pos battery and solenoid, between neg battery and chassis.

If still problems jump the cable between the pos battery and starter motor terminal on the starter solenoid to bypass the starter solenoid.

There is also a electrical cable between the engine and chassis. Make sure this cable is in place and in good condition.

Clicking is generally a sign of a poor electrical connection. The common cause is the starter solenoid electrical contacts but you replaced the complete starter.

The other common issue is corrosion at the battery cable terminal connections.

As to the injector.

You can remove the starter injector and with electrical wires still connected test it by engaging the starter. Fuel squirt out of the injector. During the test suggest you disable the engines ignition system so the engine will not start and have container to catch the fuel.