E28 525E - Has spark and fuel but wont start

[Bonto 14]

Hi all,

I just bought this the other day - ran fine for two days then one morning after a long idle (warming up and de-icing the screen) it just stopped and wouldn't restart.

I've checked fuses, looked at relays (don't have a meter so not much further there..) and there is heaps of fuel coming out of the front end of the fuel rail. Big blue spark from sparkplug number one too.

SO I'm guessing it's a sensor that talks to the fuel injectors? I'm not great at electrics but wondering if any of you can help point toward a likely cause? Or suggest what to pull off and clean up?

The car hasn't been well maintained, but it was running strong for about 100km before this. Any help much appreciated.

Cheers

Tom

[e30ftw 396]

So there is fuel going to the fuel rail, But have you checked if fuel is going into the engine? Are the spark plugs soaked after cranking?

There is a plug under the manifold connected the injector loom to the engine loom, could be a start if you know the injectors aren't firing.

Or you can have a look on the e30zone wiki there is very good troubleshooting steps and understanding of what controls what and narrowing down a fuel problem.

http://www.e30zone.net/e30zonewiki/index.p...uel#Controlling

[Bonto 14]

So there is fuel going to the fuel rail, But have you checked if fuel is going into the engine? Are the spark plugs soaked after cranking?

There is a plug under the manifold connected the injector loom to the engine loom, could be a start if you know the injectors aren't firing.

Or you can have a look on the e30zone wiki there is very good troubleshooting steps and understanding of what controls what and narrowing down a fuel problem.

http://www.e30zone.net/e30zonewiki/index.p...uel#Controlling

I did pop a plug out to check for spark - I'd call it oily/sooty rather than wet with fuel. Also we did get it firing on quick-start / ether, so the timing and ignition seem to be OK. My hunch is the injectors are not injecting...

[Silver Fox 43]

probably crank sensor or ECU?

[e30ftw 396]

But if it was the crank sensor or ECU, there wouldn't be a spark (how would the spark plug know when to fire if it wasn't getting a feed from the crank sensor for engine position and the ECU to send out to the coil?)

You need to check and clean the connectors in that plug where the Injector loom plugs into the main engine loom, it is between / under the intake manifold. Or pull out the fuel rail and get the injectors to point into 6 bottles and crank the engine to see if they actually fire or not.

[Silver Fox 43]

moisture in the ecu can kill the injector signal, I know from experience, that great teacher.

You can put a screwdriver or stethoscope on the top of the injector, it ticks as it opens.

[Bonto 14]

But if it was the crank sensor or ECU, there wouldn't be a spark (how would the spark plug know when to fire if it wasn't getting a feed from the crank sensor for engine position and the ECU to send out to the coil?)

You need to check and clean the connectors in that plug where the Injector loom plugs into the main engine loom, it is between / under the intake manifold. Or pull out the fuel rail and get the injectors to point into 6 bottles and crank the engine to see if they actually fire or not.

Thanks for this - it makes sense. I've bought a new DME relay to cancel that out as a possible cause. Will have at that plug tomorrow. That link you sent through was excellent too.

Cheers

[Bonto 14]

moisture in the ecu can kill the injector signal, I know from experience, that great teacher.

You can put a screwdriver or stethoscope on the top of the injector, it ticks as it opens.

Also good to know. It's cold and wet outside so I'm not all that keen to pull the rail if I can avoid it, or until I can get the car into the garage!

Cheers

[Etwenty1 45]

I did pop a plug out to check for spark - I'd call it oily/sooty rather than wet with fuel. Also we did get it firing on quick-start / ether, so the timing and ignition seem to be OK. My hunch is the injectors are not injecting...

Check the actual flow/pressure of the fuel, not just that there is fuel at the rail. A dying pump can give a weak flow.

[Bonto 14]

In case anyone is vaguely interested: the fault was a bung computer. Soon as we sourced a replacement it fired up right away and has run well ever since.

Still wants front wheel bearings (horribly expensive damned things), control arm bushes and vacuum hoses but for now it's good enough. Thanks for all the help.

Tom