'74 2L Starts Then Dies, Never a convenient time... Options

[GregAmy]

Nice beautiful New England Day, heading off to the Manchester CT car show and...car won't start. Cranks, a few cylinders fire, then it dies. I cycle the key and hear the pump running and then stop (as before) and same thing: spits then dies.

I tried cycling the key a few times, with the mindset of building more pressure, and it spits a few more cylinders then dies. Even got it to rev a little bit with a half-dozen key cycles, but always dies.

Only other symptoms is that I noticed the last time I drove it earlier in the week it was dying when I put in the clutch. Was not consistent, only did ti a few times, but that was unusual behavior.

Stock 2L fuel injection, but with cold start and idle air bypass systems disabled; been running fine like this for the several years I've had it.

Checked all the relays, each works with the heater blower. Swapping them makes no difference (which I expected, given the pump cycles with the key). My guess is that however the pump is supposed to continue to run after releasing the key, it's not getting the power it needs (just a guess, I've not gotten under there with a voltmeter to verify). The wiring diagrams are not clear (to me) how that power is applied to the fuel pump relay.

Any way to quickly salvage my afternoon trip to the car show, or am I using my beautiful afternoon to swap the street car onto the lift for extended diagnosis?

40-yr-old electrics, gotta love 'em.

- GA

[GregAmy]

OK, here's some more data.

I was playing around with it just now, and of course without an AAR it idles like hell cold (future project). Started it a few times, fuel pressure is now at 30 steady, and then one time it died. And then it wouldn't start, same symptoms! Crank, brief fire, died.

So I break out the brake cleaner, open the TB and give it a squirt, then get in the car, starts up fine and I can keep it running with my foot, though it is running rough. Eventually it warms up enough to idle on its own. Starts and runs fine now.

Then I remembered something. A couple summers ago I had a hell of a hot start problem, where the car would not start when really hot, and I could smell fuel. If I kept my foot on the floor it would eventually fire and I could be on my merry way. And the car was getting shitty fuel economy, to the tune of 19-20 mpg.

Before you ask...fuel pump is in the front.

In reviewing the system - recall this car was a basket case when I got it - I found that there was no thermoswitch installed, the one that grounds the cold start valve. So, obviously, the CSV never worked and on the possibility that it was leaking I removed the hose and disconnected the plug.

I'm now thinking that this may be a/the problem, especially since it starts ok on brake fluid.

I searched through my Box O Parts and I can't find a thermoswitch. And it took about a half hour to find the wire for it as someone had just cut it off (it's another white wire buried inside the same pigtail as the harness for the distributor trigger points.) I still don't know if my CSV was the hot start problem, though I never had that problem again after removing it, could have been coincidence.

So I guess my next step is to obtain a thermoswitch and install it, and repair the wiring harness to it, and remove and test the CSV for wiring harness grounding and leaking.

Anyone have a thermoswitch and/or CSV laying around?

What is the correct control function of the CSV? I've read in one place that the valve only gets power from the ECU under cranking conditions, but I read in another place that if the thermoswitch fails closed the CSV is running all the time.

1:32 PM EDIT: We having fun yet? CSV does not leak under constant 30 PSI. CSV does not fire with key in the "on" position when wire for thermoswitch is grounded. CSV does fire when key is moved to the "start" position, then stops when released.

I need a thermoswitch.