Cold start valve firing/cycling on and off constantly, even with the motor hot. I've never Seen one fail like this before.

TPI setup, 1985 style, happens to Not be on the 'vette, but on the alternate transportation 1978 pickup truck. Long story there, but I wanted it to be interchangeable with the car, and it is. Essentially a 100% "stock" '85 TPI system, the only real modification is an oversize throttle body. No AIR or EGR, but the cold start is there, which is the issue.

Anyhow - it began acting weird and running strangely a couple of weeks ago. At the moment I'm driving the thing nearly every day while the 'vette is "trapped" at home - it's Mud season here in the hills of western Massachusetts and I live on a dirt road. Not pretty, but improving - another couple of days and I hope to be back in the Car.

Symptoms were similar to leaking injectors - seeming rich at idle, particularly when first starting it cold. An unstable idle (to the point of stalling, occasionally). No codes, no indications of anything out of whack while monitoring the scan tool. Once warmed up and running down the road would usually seem to Run fine, but stopping and hoping for it to Idle was an adventure. It Felt like a two cylinder miss, and sure enough cyl's #6 and 8 were Apparently the "weak" ones when doing a plug wire check, although it wasn't a Spark issue. Nor compression. One thing I Did find - the fuel pressure would drop off right away when the pump stopped running - making me think leaking injectors (or whatever else, like a bad pump check, or regulator).

I was thinking vacuum leak, and or leaking injectors on those cylinders. Then, yesterday, I was messing around with an (unrelated) under dash electrical upgrade and had the ignition switch on/not running in a quiet garage. I could hear Something cycling on and off under the hood, sort of a Relay switching sound, but quieter.

Turned out to be the cold start. Just always cycling on a 5-6 second on/off period. As long as the power was on, and even with the motor fully warmed up.

I've never seen one of the cold start Switches Do that, before now. Weird. Does explain the problems, I'll find out today of all of the driveability issues are actually cured.

 

Wow, sounds like time to ditch it. Better check your oil for gas.

 

It's about to happen anyhow - the reason I was under the dash was to sort out wiring for a new electronic speedometer, part of getting ready for a complete driveline swap in this old thing. Replacing the motor, transmission and transfer case going from an sm465/np205 to a 700r4/np241. Something with an overdrive...

Also taking the tired 350 long block Out and swapping in the less tired 350 long block from the donor truck that's providing all of the other parts for this upgrade.

Not to mention swapping in the A/C system, power locks and windows, etc. Gotta have projects.

 

Man, I envy you guys with the time for projects like that - good luck.

 

disconnect the cold start valve's plug. Yes it will make it harder to start on a cold morning but its better than running pig rich while driving.

 

Hmm - looking at the FSM it appears you are correct - I have the thing hooked up wrong on this installation, and it's getting power in Run, not in Crank. Still isn't Working right, but at least it wouldn't be as noticeable..

Ah, well, it's going to get lost during the upcoming motor swap anyhow.

BTW, driving the truck yesterday (with the cold start disconnected) it seems to be fine, no issues. Back to normal.

Time is always the holdup, that and Money. It isn't like this whole swap deal hasn't been in the works for some time now, I've owned this truck for 16 years, waiting for the time/opportunity to do something like this with it..