CIS Warm Start Issue - Cold Start Valve

[tkmoore]

Guys, I know I'm coming at this issue in unconventional manner but I'm working on a warm start issue on my 83 SC. I had WUR fixed and adjusted by a good shop last fall to fix cold start problem. Now upon warm start, car quickly dies if hot, or if semi cooled idle fluctuates up and down for a few minutes then eventfully idles stray as it should. I've not got access to guages right now to check pressures, but I've checked for vacuum leaks (seem to have none) and scoured the fuel lines for leaks(finding none). Studying my Bentley I started checking my Cold Start Valve system today. On warm start today car had same symptoms but as soon as I unplugged the CSV it idled fine. Does this indicate a bad CSV or is it likely the thermatic temp switch is telling the CSV to spray fuel improperly? I appreciate the help as I'm still learning about the CIS. Thanks,

[ossiblue]

Originally Posted by tkmoore

Guys, I know I'm coming at this issue in unconventional manner but I'm working on a warm start issue on my 83 SC. I had WUR fixed and adjusted by a good shop last fall to fix cold start problem. Now upon warm start, car quickly dies if hot, or if semi cooled idle fluctuates up and down for a few minutes then eventfully idles stray as it should. I've not got access to guages right now to check pressures, but I've checked for vacuum leaks (seem to have none) and scoured the fuel lines for leaks(finding none). Studying my Bentley I started checking my Cold Start Valve system today. On warm start today car had same symptoms but as soon as I unplugged the CSV it idled fine. Does this indicate a bad CSV or is it likely the thermatic temp switch is telling the CSV to spray fuel improperly? I appreciate the help as I'm still learning about the CIS. Thanks,

Could be either one.

Unplugging the CSV removed both power and ground circuits to the CSV so unless the valve was stuck open or leaking, it would provide no fuel. That solved your issue, but leaves you without knowing the culprit.

Next time, disconnect the wires from the thermotime switch, preferably just the red/black one. That is the ground circuit to the CSV, but the CSV will still be getting power through the yellow wire at its connector. If that fixes your issue, then the thermotime switch was the faulty part as it was not breaking the ground circuit, when warm, as it should.

If the issue remains, then either the ground wire that you disconnected is shorting to ground (allowing the CSV to operate)or the CSV is faulty and is grounding itself.

BTW, you can do an alternate test with a trouble light or multimeter. With the engine fully warmed, unplug the connector to the CSV. Connect one lead of the light/meter to a power source, and touch the other lead to the socket in the connector for the ground (red/black wire.) You should get no light/reading. If you do, the wire is still grounded and either the switch or the wire is faulty. Repeating the test at the switch itself (with the wire disconnected) will tell you if the switch is bad.

[T77911S]

the CSV should ONLY get power when starting. if the CSV has power after it is started then it is wired wrong. check to make sure you have the correct connector plugged into it.
the TTS could be working as it should.

just curious, does your fuel pump with the engine off and the key ON,

[boyt911sc]

Originally Posted by tkmoore

Guys, I know I'm coming at this issue in unconventional manner but I'm working on a warm start issue on my 83 SC. I had WUR fixed and adjusted by a good shop last fall to fix cold start problem. Now upon warm start, car quickly dies if hot, or if semi cooled idle fluctuates up and down for a few minutes then eventfully idles stray as it should. I've not got access to guages right now to check pressures, but I've checked for vacuum leaks (seem to have none) and scoured the fuel lines for leaks(finding none). Studying my Bentley I started checking my Cold Start Valve system today. On warm start today car had same symptoms but as soon as I unplugged the CSV it idled fine. Does this indicate a bad CSV or is it likely the thermatic temp switch is telling the CSV to spray fuel improperly? I appreciate the help as I'm still learning about the CIS. Thanks,

tkmoore,

You have been given sage advises by Larry and Ty. My only comment would be that CSV seldom breaks down and same with the TTS. You need to bench test them to determine if they contribute to your problem/s. Without knowing your fuel pressures, you are leaving too many unknown variables. Lastly, I have a suspicion that your fuel mixture is very rich and you have unmetered air. Without testing the integrity of your vacuum system, you are hoping that there would be no significant source/s of air leak. Which could be true but you don't know that for a fact. BTW, a good and honest shop does not mean that the technician who worked on your knows well about CIS troubleshooting.

People have replaced parts like CSV in the past to troubleshoot their CIS problems. Test and confirm that the suspected CIS component is defective before buying a replacement.

I have yet to find a non-working CSV in a CIS system. Well, I found one earlier but it was caused by an electrical issue. Keep us posted.

Tony