Ambient termperature effects

My '77 doesn't like warm weather.
At anything below about 45-50 degrees (F), she starts with a mere touch of the key.
Once the outside temperature starts to climb above that, the challenge begins.
I'm leaning toward a fuel delivery or mixture problem. A squirt of starter fluid into the air filter horn seemed to help the one time I tried it. Sometimes adding just a little pressure on the throttle seems to help. I'm thinking it might be WUR or AAV (both of which have bi-metal strips doing some of their work. Don't know what else might be so affected by such a small change in air temp.
BTW, warm engine usually starts easily in warm weather, it's mostly a cold-engine start problem.
Anyone else with experience tracking down this sort of problem?

[stlrj]

Try a new thermo-time switch. It should remain closed at 15*C (59*F) or install one that is rated at 20*C which would keep your cold start injector working at a higher temp.

Cheers,

Joe

Seems I could easily verify the need for this by bypassing the TTS when I'm having starting problems.
A temporary jumper from the wire on the switch to ground, removed once started. (With a switch on said jumper, it becomes a manual "choke" )
If it started easily with the jumper in, then the switch is causing the problem

[stlrj]

That will work too. Seems I did that once upon a time.

Joe

temp hit 90+ yesterday. I got started (with a little help from dragon-in-a-bottle) but rough running forced me into a park-and-ride lot less than a mile from the office.
45 minutes later, I'd run out of things to try and run the battery down quite a lot.
Locked her up and sat thinking for a while, called a few friends, looking for a ride home.
Finally caught the bus. Called for a flatbed when I got home and had her dropped at the garage.
They began checking things out this morning and confirmed my long-held suspicion - the fuel pump was managing only ~2bar of output. Not nearly enough.
Should have a new one in tomorrow. We shall see what we shall see.