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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

Cold start problem??

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Old Nov 29, 2010 | 05:28 PM
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Cold start problem??

i have been having a cold start problem jus in the cold mornings it takes forever to start, so my first idea was to test the cold start injector time switch, i took my voltmeter and put the positive on terminal STA (power) and my ground on terminal STJ (ground) on the sensor, then at 22 degrees i got 53.4 ohms, does anyone know if the sensor is good or not? or what are the specs on testing it?
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Old Nov 29, 2010 | 06:05 PM
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it is 22 F
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Old Nov 29, 2010 | 06:56 PM
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Question

why are the ohms so high?, cuz it says 86f and below it should read 20-40 ohms, y is mine reading 53.4 ohms?
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Old Nov 29, 2010 | 07:17 PM
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no this is the time switch its on the left it was 22 F degrees and it read 53.4 on the sensor
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Old Dec 2, 2010 | 06:48 PM
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I tested the wires up to the cold start injector and I have 12 volts and I unplugged the coil and turned it over to see if the cold start injector would spray and it didnt, so I figured I had a bad cold start injector I bought a new one and put it on and it still don't start easily, it takes forever, and I am getting fuel up to the injector any ideas????
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Old Dec 2, 2010 | 09:47 PM
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What year is your truck?
On the cold start injector, the STA terminal is the hot ( 12v) and the STJ terminal is ground.

When you turn the key to start, power goes to STA, through the cold start injector( opening it and releasing fuel) and to ground through the Cold Start Injector Time Switch. When you do this you also send power to the heater elements in the cold start switch, which limits the time the injector stays open ( only a few seconds( depends on the outside temp). On some models the ECM can overide the cold start switch and keep the injector open longer. If the engine is cold and you dont have ground from STJ through the cold start injector switch, the the switch/ wiring is bad.

When testing, the engine has to be cold enough for the switch to be closed, if you dont do it quickly the heaters will open the switch.

Last edited by sam333; Dec 2, 2010 at 10:06 PM.
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Old Dec 2, 2010 | 10:21 PM
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Originally Posted by razed
< 10C (50F)= 30-50 ohms
> 20C (68F)= 70-90 ohms
Originally Posted by boostedyota
why are the ohms so high?, cuz it says 86f and below it should read 20-40 ohms, y is mine reading 53.4 ohms?
For what it's worth, my 1994 FSM says:
< 10C (50F) = 30-50 ohms
< 25C (77F) = 70-90 ohms
I doubt this is a difference that makes a difference, so it looks like boostedyota's cold start timer at least passes that test.
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Old Dec 2, 2010 | 10:55 PM
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So we know the switch is closed and resistance is close enough, but does he have continuity from STJ to ground?
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