Brickers:

Lately I've been experiencing an annoying starting issue with my 1985 745t (207k miles), and I'm hoping someone has some idea what it might be.

When I leave the car idle for 2+ days the car will start, but it will initially chug a bit (2-3 seconds) like its running at 100-200 rpms or so. The tach will then shoot up to about 1200rpms, and drop down to 1000rpms until it gets a little bit warmer. After that the tach settles to a normal 800rpms or so and runs fine. The car never fails to start entirely, but it sounds like its struggling initially when its idle for a while. The temperature fluctuates between 25f and 54f, but every time I've experienced this it has been around 50f-54f, so it wouldn't seem to be a cold related issue.

I haven't experienced any other running or idle problems at all, and I'm a bit dumbfounded as to what could be causing this.

My initial thoughts revolved around the fuel filter/main pump, fuel lines, or maybe even the ignition switch. In the case of the latter, I know my switch is worn because I have the no dash/electronics on start from time to time and have to jiggle the keys. Is it possible the switch isn't starting the pump prior to ignition? Would this matter, and wouldn't I also experience this all the time (instead of just when the car is idle 2+ days)?

I don't smell any gas, so I don't think its a leak or anything. My pre-pump, sender assembly, FPRegulator, and FPRelay are all new and it ran fine when I initially replaced each of them, so if it is a fuel issue I'm inclined to believe it is the main pump or filter. Is it possible I have a TINY leak somewhere that is allowing pressure to decrease in the fuel line, and that its so small it takes 2+ days to be noticeable?

Any help is greatly appreciated.

Thanks,
Rick