1986 4runner hard start issue (video)
 

Hello! This is my first post on yotatech so I am sorry if this is somehow out of place... I picked up my 86 4Runner with 360000 miles on it.lots of little things have been done to it, but the two previous owners had taken good care of it overall. Now on to the real problem

All summer the vehicle has started just fine, but now that it's getting colder here in Oklahoma, the starting just gets more and more difficult as the temp drops. This morning I managed to capture a video of how the problem normally appears.

The engine, mechanically, is sound, and the only true issue is a bad timing chain guide. I have given it a complete tune-up (except for putting in a new coil) and the battery is an OK one...

Whenever the ambient temperature is exceptionally cold, it will be so hard to start that I will simply give up and drive the other whip...

I tested the cold start injector, and it is working and I am about to check the cold start timer as well.

Heres the video


What do you guys think???

Thanks

How did you "check" the cold start injector? The easiest way to do is to pull it out of the intake (with the fuel line still attached), put it into a suitable container, and crank. (Don't disconnect the fuel line. The "crush washers" are one-time use and MUST be replaced if you open the fuel connection.) Obviously, you want to do that cold, as it "tests" the CS Timer Switch as well.

Ok, I tested the switch when cold and am getting spray, but I've yet to test the timer switch and see the actual spray. I'll test it tmw when I have someone to help me out! I'll keep you all updated...

Ok, I tested the timer switch and lo and behold, the ohmage is 80 when it was 40*F outside (aka broken :P ). I'm going to get a used one off of ebay and put it in, but I will also see if I can rebuild my old cold timer switch/thermo. If I manage to rebuild it and get proper readings, Ill add some pictures here of how I did it. Crossing my fingers!

I think this is the source of my hard cold starts too. Mine is a bit closer to functional at 53 ohm at 60˚.

Yup my 92 22RE was doing the same thing last Spring, and it was the thermal time switch.

I bought Beck/Arnley from RockAuto hoping for a factory Toyota part. Sure enough it was an original Toyota part in a Toyota plastic bag same as ordering from a Toyota parts dealer.

https://www.rockauto.com/en/moreinfo.php?pk=482766&cc=1277939&jsn=387&jsn=387

This makes sense. The thermo-timer switch will shut off the cold start injector at that high of a resistance.

If the cold start injector thermo-timer switch reads incorrectly to the hot resistance, the cold start injector does not turn on when starting the engine form cold. The fuel mixture is too lean when only the regular four injectors are firing and it takes several cranks to get enough fuel in the cylinders to start.

The colder the ambient temperature, the richer the fuel mixture needs to be to start and the harder it is to start without an operational cold start injector.

The thermo-timer switch is the more failure-prone component for the cold start system.

I am glad you found the culprit! :wrench:

:safari:

I'm not sure that's your problem. The purpose of the Cold Start Timer switch is to allow the CSI to spray when cranking, WHEN it is cold enough. Even when it is cold enough at first, an internal heater in the Timer Switch cuts off the CSI after a few seconds of cranking, no matter how cold it is. The resistance check in the FSM tests a combination of the internal switch and the heater (a more useful test for HARD starting, which is not in the FSM, is to test STJ to ground).

If I understood your earlier post, your CSI opened (sprayed) with cranking when cold. So that part (the part that has to do with hard starting) is working.

scope103, seems you saw a logic error in my previous replies. I meant that when I used a jumper wire to the CSI, it had spray! When the CSI is controlled by the thermo switch, nothing happens (no spray). Sorry for the confusion :D

The CSI is just a coil; it has no polarity, so swapping the wires to the CSI should make no difference. (The two wires to the CSI Timer Switch have different functions, so reversing them will stop it from working.) Of course, any time you clean up hacked wiring, you could fix something (a bad splice?) that you didn't even know was there.

If Bloku has the Timer switch out (or even better if not, as long as he can get a meter on it), I would be very interested to know the resistance from STJ to GROUND, and the resistance to the body of the Switch. As I mentioned (and Rad4Runner points out in the linked post), there is no FSM spec for that, but that is the connection that actually opens the CSI.

If STJ to the body is open, you might have to put it in the refrigerator to get it cold enough. If still open, the Switch is bad (though I wouldn't know WHY it is bad).

I suggest testing resistance to both the body and to ground because Rad4Runner believes he has had issues with a bad ground connection between sensors and the water jacket. If you have continuity (any resistance less than about 200 ohms) to the body, but much higher resistance to ground, your Timer Switch may be good, but somehow not adequately connected through the mounting threads.

Ok, thank you guys! I went ahead and purchased the the switch after doing wiring checks. All the "checks" pointed to the thermo time switch. Bought the switch off of 22re performance - Website - and it worked great! No hard starts in any weather (coldest example was about 25*f). Seems it really was that easy.

Good job! :great:

The diagnosis was confirmed to be correct.

Thanks for posting your results.

:safari: