X5 cranks but won't turn over-Help!

[jasondlyman]

Originally Posted by LeiZ

You need to report back more info: what's the fuel rail pressure when key on?


Sent from my iPhone using Tapatalk

I'm pretty ignorant when it comes to auto stuff so can you tell me how I check the fuel rail pressure? Thanks!

[upallnight]

Originally Posted by jasondlyman

I'm pretty ignorant when it comes to auto stuff so can you tell me how I check the fuel rail pressure? Thanks!

I would suggest you look for a mobile mechanic in your area, or look for a shop that is familiar with BMW.

There are plenty of Youtube videos on how to test the fuel pressure in a BMW. But since you admit that you are pretty ignorant on auto stuff, it is very likely that you are not a DIYer and lack not only the knowledge but a good set of automotive tools such as a fuel pressure gauge.

[SlickGT1]

First thing I always do on a BMW that I have had, is pull the damn maf plug, and try again. A lot of shit goes to default maps, and it might start. Got my brother home 50 miles away when his 328 wouldn't start, just cranked.

[upallnight]

Originally Posted by SlickGT1

First thing I always do on a BMW that I have had, is pull the damn maf plug, and try again. A lot of shit goes to default maps, and it might start. Got my brother home 50 miles away when his 328 wouldn't start, just cranked.

Since the engine and 02 sensor are stone cold, he is already in open loop. Pulling the MAF plug only cause an engine to go into open loop where it uses the default fuel map in the computer instead of using the 02 sensors to control the fuel mixture.

Here's a mobile mechanic in Colorado Spring, perhaps he is willing to travel to Peyton Co to work on your car.

AMOBILE1AUTOREPAIR

[upallnight]

What does the gas gauge read on the dash? It it more than half full, or is it less than half empty?

[oldskewel]

Originally Posted by jasondlyman

I'm pretty ignorant when it comes to auto stuff so can you tell me how I check the fuel rail pressure? Thanks!

Open the hood. Pop off the cosmetic plastic clips on the engine covers. Remove the 10mm bolts holding the covers on. That will expose the top of the engine.

You'll see on top of the engine, near the middle, running front to back, a ~1cm-square Aluminum tube. That is the fuel rail, which feeds all the fuel injectors. About 20% of the way from the front of the rail, pointing straight up, is a Schrader valve, covered with a chrome cap. This is the same type of valve on your tires, but with different sealing materials due to the gasoline contact.

You can unscrew the cap and then screw a fuel pressure gauge into that valve. If you don't have one yourself, you may be able to borrow one from PepBoys, etc. Since it is a Schrader valve, you can verify that the gauge is assembled and working correctly by first using it to measure tire pressure.

You should expect some gasoline to leak out when you do this test (although if done perfectly, none should). For safety reasons, when finished, you should hose it off. You don't want gasoline puddles on your engine when starting it. To be safer still, you might disconnect your battery before doing this too. I did not.

I did this on my 2001 3.0i a couple of weeks ago on my way towards replacing the fuel pump. In my case it was pretty easy since fuel pressure was zero (so I did not really need a gauge). After replacing the fuel pump, I carefully cut open the old one to figure out exactly what went wrong. At 175k miles, it looked in great shape except both brushes had worn nice and evenly down to the wires. So it was just normal wear.

In case you think your problem might be with the fuel pump (I have not read through all of the symptoms you list), simpler preceding tests you can do are:

- Open the fuel filler, remove the gas cap. With your ear up to the opening, have someone turn the car to on (not start), and listen for the fuel pump to run for a few seconds and then turn itself off. That's what it should do. If you hear nothing, you could have a fuel pump problem...

- If the preceding test was silent, pull up the rear bench seat. No tools required. Just pop it up at the front and pull it out - rest it on the left seat so you don't need to deal with the seatbelt going through it. Nothing needs to be disconnected. You can then see the fuel pump entry point to the gas tank under the right rear seat. 4 10mm screws hold the cap on. You can check for activity again at the fuel pump. Then check supply voltage and resistance to the pump (2-wires - I think the ones toward the left, supply the fuel pump, the other two are a variable resistance for the fuel level sender; both resistance pairs should have reasonable values - not zero or infinity). Measuring the corresponding terminals on the (disconnected) connector should show +12V when the fuel pump should be running - which is for a few seconds when first turning the key to ON, and then remaining running while the engine is turning. If you have no fuel pressure, and do not detect 12V there when you should, it points to a fuel control issue - with the DME or CPS or ???.

Good luck!