E39 528i not starting

[Mad_Max 233]

A friend of mine has a '97 E39 528i, pretty straight and tidy. I checked it over for them before they bought it about 6 months ago, and couldn't fault it for it's age. Also scanned it at the time with ISTA, only minor historical fault codes came up. The only known issue with the car was bad fuel level senders.

I've been getting a few small things sorted for them, to clean the car right up. Recently, swapped the drivers side sender and fuel pump over (having swapped the passenger side previously), swapped to the better MID display, and swapped steering wheels to one in better condition. After changing the fuel pump, the car was started and ran perfectly, confirming the pump itself was fine, so I then moved on to the MID and steering wheel jobs.

Now, the thing won't start. Winds over sounding like it's low on compression. Scanned with ISTA again, all fault codes erased, then tried to restart. Fault code 000041 DME fault is showing, with no description in ISTA on what the fault will be. No other fault codes existing for it that will cause the non starting issue.

I've confirmed the fuel pump works by pulling the fuel line at the tank, hooked up a hose into a container and turned the key - fuel flows - but will swap back to the pump that was removed, swap the MID and steering wheel back and see if anything changes.

ISTA is saying (I think) that the EWS and DME are in synch, as it says all the numbers are matching - first thought was to realign the EWS in case I'd messed it up when the battery was disconnected to swap the airbag - unfortunately I can't do that in ISTA-D and (of course) ISTA-P isn't currently loading, so I can't check that.

I am assuming ISTA would tell me if it was a crank/cam angle sensor, or if the EWS was out of alignment - is that correct, or is my thinking flawed? Does anyone have any other troubleshooting suggestions? I've got a parts car the same (with unknown state of the parts) so don't mind throwing parts at it, just really want to get it sorted for her as she's stuck at home atm.

Edited April 11, 2020 by Mad_Max
Spelling mistake

[Eagle 1680]

How long did you run it for? Maybe you flooded it

[Mad_Max 233]

It ran for a few minutes, then sat for a few days before I did the rest of the work and the no start issue arose, so I don't think flooding is the issue. Gonna pull the plugs and double check what's going on, old school test for spark and will probably test compression too just to rule everything out.

I'm still looking for that clip for ya too man, if you still need it. Have had a few searches but haven't emptied every box yet. If I find it I'll let ya know and get it on it's way to you.

[BM WORLD 1286]

sounds like cam sensor faulty , unplug it and pull back the rubber boot to see crumbling insulation .

or could also be crank sensor

sometimes if you just floor the throttle and keep cranking it will start again 

[Mad_Max 233]

Crank sensor was replaced within the last year after that failed, so I'm assuming that is fine. Wouldn't the cam and crank sensors show as faults in ISTA though?

Battery is currently on charge as that was getting down, so hopefully a good charge and that will rule that out as well.

[Mad_Max 233]

So the plot thickens...... have swapped both cam and crank sensors, the DME fault code that was previously showing in ISTA has now gone away, but still no start. There doesn't appear to be a lot of fuel in the rail, so I'm back to thinking it's an EWS issue.

Any other thoughts or suggestions? Cause this is getting frustrating. Everything that was swapped over has been swapped back to the original (fuel pump, MID etc).

[BM WORLD 1286]

23 hours ago, Mad_Max said:

So the plot thickens...... have swapped both cam and crank sensors, the DME fault code that was previously showing in ISTA has now gone away, but still no start. There doesn't appear to be a lot of fuel in the rail, so I'm back to thinking it's an EWS issue.

Any other thoughts or suggestions? Cause this is getting frustrating. Everything that was swapped over has been swapped back to the original (fuel pump, MID etc).

while cranking is there volts at the fuel pump

[Mad_Max 233]

2 hours ago, BM WORLD said:

while cranking is there volts at the fuel pump

I haven't checked that yet, messing with it yesterday bleeding the fuel rail I managed to get it to fire and run for around 10 seconds, so I'm thinking the fuel pump relay is shot - that would explain why no fault codes are showing.

Will check voltage at the plug and swap relays out, see if that makes any difference.

[BM WORLD 1286]

3 minutes ago, Mad_Max said:

I haven't checked that yet, messing with it yesterday bleeding the fuel rail I managed to get it to fire and run for around 10 seconds, so I'm thinking the fuel pump relay is shot - that would explain why no fault codes are showing.

Will check voltage at the plug and swap relays out, see if that makes any difference.

yup remember too , the ecu will only turn on fuel pump relay when it gets a crank signal , no signal no fuel 

[Mad_Max 233]

All sorted now, fuel pump relay was the culprit - didn't even bother checking voltage at the pump. All the terminals on the 3 relays in the boot were showing signs of bad corrosion, so I swapped them for ones in much better condition, hit the key while the fuel rail bleed valve was held open, and fuel gushed out. 10 seconds later it was running fine.

First time I've ever run across this problem with an E39, so something to keep in mind for future.

Thanks to all for help/suggestions, my friend is grateful her car is now going again. And I am glad that the crank sensor has also been changed, when it was changed by the previous owner it had a cheap aftermarket sensor installed so that has been replaced with a genuine one for peace of mind.