I remember read somewhere, the fuel doesn't return to the tank at start up. If it does, it is the problem with the fuel regulator. When you turned the key on, the fuel pump only buzz for a few seconds. The fuel pressure remains in the system after the fuel pump turned off.
If the crank/cam sensors have wore out, the engine would still start up, but the engine dies when they act up.
Run the proper tests with the correct equipment.
Get the book or the disc. or download if you can safely, the correct procedure and specs. Run all the tests for a no start.
The vacuum applied to the regulator would reduce fuel pressure returning it to the tank.
Run your tests after you read all about it. if you dont do bimmers, then you get to read a bunch.
It's possible there is a problem you may have overlooked even with a new part.
Sounds like it runs out of fuel pressure or fuel prime intermittantly.
The water pump could still be equipped with a phenollic impeller (just a side note)
Oh, and I believe the car has about 120,000 miles. All the fuses and relays are good, it probably needs an oil change, and the timing belt was supposedly replaced shortly before we bought the car. I don't know if any of that makes a difference.
In my experience when a car has performance problems on the road but idles OK it is fuel related provided you are confident in the plugs/wire and the spark delivery.
I asked this question a few days ago, but I wanted to ask it again with more detail. My brother's 1986 BMW 325e was running a little over a month ago. Every time we would take it out for a drive, it would begin to cut out and hesitate, and then stall. Then after it would stall, it wouldn't start until later in the day after we got it towed home. Then, the last time we got it home, it sat in the driveway for a week, and then it wouldn't start. So I've been checking things on it since then.
It cranks just fine, I've swapped the DME/ECU with a spare one, both fuel pumps run (there's two), the fuel filter isn't clogged, there's fuel to the fuel rail and injectors, there's injector pulse, the distributor, ignition coil, spark plugs and wires are all new and there's spark when cranking. Just as a test, we tried some starting fluid, and it does fire up, but it dies after a couple seconds when the fluid is burned up. Since there's spark and fuel, and it starts with starting fluid, it shouldn't be the crank position sensor.
The only other thing that I've read is possible of causing it not to start is the fuel pressure regulator, but that's a less common issue. I removed the vacuum line from the regulator, covered the hole on the regulator with a paper towel, and cranked the car for a few seconds. The paper was dry, so fuel isn't being sucked threw the vacuum line. I also removed the return line on the regulator, and nothing came out when cranking. Could it be stuck shut?
