Cold Starting

[mholmes]

My son's car is a bear to start when it's moderately cold. It will immediately fire up run for a second or two and then die. You can re-crank it but it will die again. This will go on for at least 3 tries before it will stay running. Needless to say with the recent cold spell that we are having this is causing major problem. Is this a bad cold start valve? Has any one else experienced this? Need help asap plz. Thx.

[sblake01]

The fact that it fires up immedaitely makes me think that the cold start valve/thermotime switch are okay. Sound more like it's not retaining enough fuel pressure and having to fill up the fuel rail before it will stay running. This is usually caused by a bad check valve or leaking injectors,

[mholmes]

Injectors are new. On the firing up, it usually turns over for 3 - 4 seconds before it cranks.

[sblake01]

Take a look at the check valve and make sure it's not letting the fuel flow back.

[deadflo]

Stephen you may be right but the symptoms do remind me of my 79 when the cold start was not working. Try disconnecting the cold start injector and see if it does the same thing. If so you may need thermotime switch or the injector.

[DatsunZsRule]

Stephen you may be right but the symptoms do remind me of my 79 when the cold start was not working. Try disconnecting the cold start injector and see if it does the same thing. If so you may need thermotime switch or the injector.

I'm glad to hear a new Cold Start Valve solved your problems deadflo but thats odd. :surprised reason I say it's odd is because usually when you have a faulty Thermotime Switch/Cold Start Valve thats malfunctioning, it will run fine when the engine is cold, then when the engine warms up to a certain degrees and the Cold Start Valve is suppose to "disable" and it fails to do so is normally when you notice the problems because it causes it to run way to rich when warm.

Anyway In addition to the replies above, I'd also make certain there are no vacuum leaks as well as making sure there are no fuel leaks anywhere.

[deadflo]

I believe in my case the valve wasn't supplying any fuel to the intake. It was leaking on the top of the valve at the connection.

I just disconnected it, and have never replaced it. My car will usually falter at one or two start attempts when cold, then start and run fine.

[DatsunZsRule]

I didn't know your Cold Start Valve leaked. In that case then yes, you would have problems with it when cold. Not safe either :nervous:

[Wade Nelson]

then when the engine warms up to a certain degrees and the Cold Start Valve is suppose to "disable" and it fails to do so is normally when you notice the problems because it causes it to run way to rich when warm. .

If I'm not mistaken, the cold start valve ONLY sprays fuel when the engine is being cranked. The 30 second time-out the Thermotime switch provides to to prevent flooding the engine during extended cranking." Perhaps Zed or someone else can CONFIRM this is how the CSV/Thermotime operate. (in theory...)

[Zed Head]

That is my understanding. I think that the mechanism of how the thermotime switch works is similar to the AAR except that instead of a bimetal strip closing a valve it opens an electrical switch. The thermotime switch looks like the ground for the CSV in the wiring diagram. The bimetal strip heater in the switch and the CSV get power from the same source, and the ground for the CSV runs through the contact side of the switch. Heat from the engine can also open the thermotime switch, just like the AAR.

Looks like DZR might think (or thought) that the CSV stays open when the engine is cold.

You realize that this is a zombie thread from 2007?...

[Wade Nelson]

You realize that this is a zombie thread from 2007?...

Oh yeah, but I assume others doing research (like I was) will benefit from corrections to the archive.

And the 60-100 ohms is just the resistance of the heater coil, so it looks like the CSV operates on full B+, a question

I asked in my private message to you.

Lastly, for anyone actually DOING research and encountering this thread, the CSV should, per the EFI "bible" spray for a maximum of 9-12 second.

[Captain Obvious]

The CSV operates on full B+, as does the thermotime switch. (Ignoring relay and switch contact drops of course.)

Neither the thermotime switch or the CSV get's any power at all unless the key is in the "START" position.

The thermotime switch will open from engine heat OR it's internal heater, whichever reaches trigger temp first.

(Haha. That's my zombie input. :ogre: )