[T2] '76 bay misfires, sometimes stalls: why?

[LJ Evans]

Fiona: 1976 bay, 2000 cc, fuel injection

I'm looking for possible diagnoses to share with the guy I found to work on my bus. I'm NOT a mechanic but seriously interested in learning more. This is beyond my limited expertise.

Here's what happens:

She misses. I had a major tune-up done when I bought her in 2011: new distributor cap, rotor, contacts, condenser, plugs, ignition wires, fuel filter, fuel lines, and of course oil and filter. They adjusted valves, set dwell, all that stuff. You folks on the list were invaluable in helping me (a) learn about my new baby and (b) give appropriate instructions to the guy who did the work.

When I got her back she ran so cherry, it was a blast. But then, every now and then, she started missing. Just once in a while. John Kolak on the list and I talked about it, we thought maybe there was a crack in one of hte spark plug wires and when it is wet, moisture was getting in there. But it does it when it's dry, too.

Last summer she stalled on me, two different times, going up the roughly one mile steep hill to my street. Total stall, wouldn't restart, had to roll her down the hill to a safe place to park. Left her there, came back later, at which time she started up and ran fine (except for occasionally missing). This is disconcerting. Last year I didn't have time or money to mess with it, and I didn't want to take her back to the same guy.

This year I located a mechanic named Rob who is the manager of a general shop, both he and the shop have a good reputation, and Rob has a bus of the same year. He tried to solve my problem. He found a wiring rig that was loose that controls the fuel injection and fuel pump. He and I were hoping that was IT. Alas, she still misses. I haven't been able to make her stall again, but I'm not driving her lots, either, as I don't want to get stranded again. 

Dang, it's so frustrating, because other than missing -- don't laugh -- she runs so WELL! Strong, engine sounds terrific, perfect, good pull up hills! 

So my best theory at this point is get a new fuel pump. I have no idea of the age of the one that's in there.

What theories do YOU have? Please share and I will take them all with me when I go see to Rob again.

As always, thanks for the copious expertise I always find on this list.

Best regards,
    LJ Evans