Needs some help - 71 stock 914, starts and runs great for 30 minutes - then fails... Options

[potomacmidget]

Dear All,

I have a 1971, 1.7L 914, D-jet, original/stock with exception of the muffler system.

Purchased from a fellow board member here, very well sorted car - has been solid for like 5 years.

As of a month ago it starts fine, then after 30 minutes runs rough, backfires and then stalls. Has happened twice, managed to get home by keeping the engine rev'd at 2K RPM and then popping it in gear and keeping it in 3rd reving high, with backfires. Once it stalls very difficult to get it to start again. Both times it has been hot out, have not experienced this before, fuel pump is in the original position and perhaps vapor lock? (but never happened in the past).

Prior to the issues I pulled distributor, replaced the points, condenser, cap rotor, and reinstalled. I exercised caution pulling it an ensured I lined it up properly. I "did" adjust the timing post distributor installation (had to find the faded spots and repaint them) and I adjusted the throttle at the screw by the throttle body. System idled great at like 750 RPM and ran fine - but then the stalling problem previously described started.

I am thinking of the following could be issues:

ignition parts? new but a bad component maybe?
timing messed up? but not sure how it would drift as it starts fine
fuel pressure regulator issue?
CHT issue?
bad coil? acts up once hot?
bad fuel?
bad relay board or D-jet pressure sensor?
bad fuel filter?

Any help appreciated. After the first failure I found I had a leaking fuel injector, leaking from the injector itself(crack). I replaced the injector and it fired up fine, but then 30 minutes later it sort of goes demonic on me...so that was not the root cause.

Thanks in advance,

Reg

[Racer]

I've had similar issues over the years:
1) crud in tank was getting into the fuel filter and clogging it, and would slowly cause the car to stop running. Wait 30 min or so, and car worked fine until the cycle repeated
2) relay board and fuel pump issues. Ran fine. would slowly loose power. couldn't keep running and stall out. Usually harder to restart and time to restart was more variable than in situation 1.

That said, each car is different.

[potomacmidget]

I've had similar issues over the years:
1) crud in tank was getting into the fuel filter and clogging it, and would slowly cause the car to stop running. Wait 30 min or so, and car worked fine until the cycle repeated
2) relay board and fuel pump issues. Ran fine. would slowly loose power. couldn't keep running and stall out. Usually harder to restart and time to restart was more variable than in situation 1.

That said, each car is different.

Thanks Racer and IIRC - will keep you posted.