I was with you until you stated, "the car is probably only worth $1500" and thus questioned yourself about paying a few hundred to replace the almost certainly guilty parts. Why is it that every decision - and almost everyTHING, really - has to boil down to dollars and cents factoring?
Either you like the car and it's useful to you - or not. Value isn't always about cost or price. Yeah, yeah, I understand that putting 2 grand into a $500 car isn't a good investment - monetarily. But what about the sentimental investment? Or the enjoyment factor? Can't we decide to do an obvious expenditure on a car just because we "like the car and want to keep it going and safe"?
@thehackmechanic - OK, this does explain your position a bit better, but it then (to me) just begs this question: if E39s are so doggone hard to work on, and you have no particular love for them, and they only add up to a "commodity daily driver", why the heck did you buy one? I'm sure, with your knowledge, you could cite at LEAST a dozen example of "commodity daily drivers" that don't have near the problematic stuff (e.g. - two hard plastic hoses that run beneath the intake manifold that are a bear to replace) that this type of car seems to. Sorry, but I'm still not following you very well. If I'm looking for a no-nonsense daily driver, I'm not buying something that I know to have parts that "I've replaced...on other E39s, only to have other parts break and strand me" - I'm gonna be looking for something that I KNOW for certain that I can drive From Boston to Jersey (and honestly, I don't even know what kinda drive that is, but it doesn't sound like much in Western states terms 😉). If it's a known "trouble-producing" car (which this model seems to be, according to your narrative), it's a poor choice for a daily driver, no?
I'm sorry, but a "daily driver" that you can't even trust to go 4 miles because it might stop running on a busy, less safe roadway isn't a "daily driver" - it's a liability. It needs to be moved along right away.
Good thought, audiobycarmine, the symptoms kinda say that - but... I'm not an expert on fuel injection, and especially not the BMW kind (being an old-school carb guy), but I'm kind of thinking that pressurized fuel-delivery systems are not as prone to the old vapor lock issues that older, low pressure systems are. So even though I thought you might be onto something, it just doesn't quite ring the bell for me.
Seems to me that 50 pounds of fuel pressure would easily overcome any vapor lock - at least in the traditional sense - wouldn't it? I'm more inclined to think that the delivery system itself, as the author suggests, such as screens or (my number 1 culprit agreement) the pump itself are to blame.
Of course, I may just be super-sensitive to the "fuel-pumps-are-at-fault" arguments right now, having had to replace one just last week with about 25 minutes to spare before I had to be somewhere! 😁