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'75 530, engine coughed sputtered and died after extended high speed run in 90+ temps. Fuel pressure showed 20 lbs. After 15 min rest, pressure at 40, it started and ran fine for 20 min then died as pressure fell. After resting several hours and being towed home it ran fine for more than 30 min. I'm thinking fuel pump? What say ye? Evidently in all my bimmer years I've never bought a pump cause I was unprepared for replacement cost, $600+. I see after market pumps for less than $200. Anyone with advice on which way to go?

Thanks

Scott

My '81 exterior pump (as opposed to in tank pump) was pumping but made a buzzing noise I chose to replace.

If they take the same Bosch pumps, autopartswarehouse.com is a good source to start pricing. If you've not done it, get original BMW fuel hose and replace all you can while you're down there.

Save yourself the adventure of one splitting lenghthwise, dumping 3-5 gallons under a hot engine in the garage.

Just get a used pump at a DIY junkyard or from someone here. They used the same pump thru the late 80s on E's 12, 23, 24, 28 and many E30s. They don't last forever, but do last a very long time. I've seen pumps with 280+K on them still working fine.

Do the '75s have an in-tank fuel pump? If so, I'll bet that's what you're problem is. I've been there.

I just picked one up from autohausaz.com for my 77 for less than $130.00 Thanks to Sherman for the link. Good idea to replace all the fuel lines you can at the same time.
You can look at the input on my post last dated 5/19 in the General Forum titled "Python Fuel Pump" one other thought when was the fuel filter last changed? I think it's possible to lose pressure while running with a clogged fuel filter because the fuel lines can deteriorate from the inside. My thought is that while running the small bits of rubber and crud move up from a settled position in the filter to block flow then when the car is off it slowly settles back to the bottom.
Similar crud can kill a fuel pump on a car that sits too long.

wkohler wrote:Do the '75s have an in-tank fuel pump? If so, I'll bet that's what you're problem is. I've been there.

Nope, they started with the 528i in 79. The gas tank is even different to accomodate it.