Cold start valve

[MrGreenJeans]

This is a follow up to my starting gremlins post where I mentioned my cold start valve causing hot start flooding. I did some further testing and here’s what I’ve got so far.

According to the WSM manual, which apparently is wrong, there should be 0 ohms on both terminals when cold. Seems like what most get from a functional switch is 30 on one terminal and 0 on the other other, which is what I get. When hot it’s 142 on the G and 70 on the W and 70 together

Looking into the wiring I’ve got two yellow wires from the 14 pin. One goes to the switch and one to the valve. There’s a brown wire coming from the switch to the valve which is connected to a ground wire that goes to the ground point by the cam cover. The ground wires go into a blue connector that looks not stick to my eyes.

I then checked continuity first looking to see if I got a beep going from G to G and W to W on the connectors to the switch and valve which I did, but what I wasn’t sure about was that I get continuity no matter how I tested the ends of the connectors and the ground point. I am a novice with this DMM but trying to learn.

Does this tell anything about why the valve might be spraying when the car is hot?

[MrGreenJeans]

Dr Bob - you mentioned in another post checking to see if one side of the valve goes to ground momentarily. How do I use the DMM to measure that?

Also is there an easy way to disconnect the starter so I can do checks with the key in the start position without actually cranking up the car. I would imagine if I pull the starter jumper I would also not get voltage to the valve

[dr bob]

This is a bit of a head-scratcher for sure.

Is the brown wire you describe actually brown-with-white-tracer? If so, that connected wire to cam cover ground is what's keeping the injector open whenever the starter is engaged regardless of the switch hot or cold. If your symptom has the cold-start injector open whenever key is in start position, lift the connected wire from ground, let everything cool before testing again. Guessing that was a hack to get more starting fuel added while starting on cold starts, but not needed on warm/hot. It functionally bypasses the switch in the thermo-time switch.

The cold-start valve only has the opportunity to open when the 50 circuit (yellow wires at pin 14 under the hood) are energized with key in position III (start).

The thermo-time switch is performing a digital function. When the coolant temp is high, the resistance through the thermo-time switch goes high/ no continuity to ground. Meanwhile the resistance through the little heater element in the switch should stay relatively constant. That should be the yellow wire that feeds the starter solenoid, the cold-start injector, and the thermo-time switch internal heater.

The injector should show battery voltage on one side with key in start position. The other side through the thermo-time switch should be at or very close to ground potential when the temp is cool/cold. It should show battery voltage when you've been cranking long enough for the heater in the switch to open the contact, or when the coolant temp is warm/hot, and you are energizing circuit 50 from key in 'start' position.

Testing the thermo-time switch installed and in-circuit can be a little tricky. The heater in the switch itself will open the switch contact in not very much energized time, well before the coolant temp is high enough to open the switch on its own. This is seconds not minutes You can use something like bio-freeze spray to force it cold again while you test, or even just compressed air or ice/cold water with care.

You can energize the 50 circuit safely without cranking by disconnecting the yellow wire at the starter solenoid, and isolating it to keep it from grounding accidentally.

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I worry when I see Scotchlock-style splice connections on almost anything in a car. In the cold-start injector and the thermo-time switch wiring, I'd have to trace some of those wires to try and figure out what the intent is. I speculated it's to get extra fuel while cranking. Without tracing the wiring that's only speculation.

[MrGreenJeans]

It’s not a brown wire like a the grounds are. I guess it’s more of a purple wire and it is spliced with that block to a black wire that goes to ground. Following the current flow it all makes sense other than the black wire.

So I gather from what you’re saying is that black wire was added at some point. I’m going to disconnect that and see what happens!