Gruppe,
I'll get the basics out of the way. '76, mostly stock M10 motor, desmogged. Stock vaccuum advance dizzy, mechanical points, standard OEM-ish coil less than a year old. Stock mechanical fuel pump of indeterminate age, replaced at some point, but never by me in the ~5 years I've owned the car. Weber 38/38 downdraft carb, electric choke, new as of September 2013.
Had a no-start symptom a year ago that ended up being the little grounding wire inside the dizzy on the advance plate. Cleared that up and car has run fine since then, with the only issue being if it sits for a few days. Car will take 25-30 seconds to crank, and then fire. Once started up, I can shut it off and it fires back up no issues. If I start the car every day, it's fine, minimal crank time. Let it sit a week or so, issue returns. This issue also seems to occur after I've run it for a while, park and try and start back up - aka stop in to the store for 30 minutes or so. I've also noticed on long road trips it does start to stumble a bit after a few hours of highway driving.
So, on the surface I'm thinking fuel issue.
Anyways, took it out this weekend from inside the garage, fired up fine, drove it around for a couple of hours, ran great. Left it parked outside overnight, came back outside the next day. Now, hot weather, ~85 degrees or so, direct sunlight ,so the car is definitely hot. Go to fire it up, and car just cranks, cranks and cranks. Nothing. Pull dizzy cap off, check grounding wire, adjust that, nothing. Play with timing a little bit, nothing. If I advance it a good bit, it tries to fire when I hold the throttle down, but won't stay running. With the engine off, I can give it gas and there's definitely fuel coming into the carb, so I'm not quite sure which way to go.
So, on first guess, I'm thinking the fuel pump has finally given up the ghost. Going to go ahead and order a fresh mechanical one and all the trimmings, but just wanted to toss it out there to see if any one had any other ideas.
Thanks.
-Charlie