Motronic 1.3 help please

[eko]

Need some guidance please with an M20B25 facelift running motronic 1.3.
Car was stood for 10 years so I’m having a crack at getting it running again.
Car is cranking fine and has good strong spark at the plugs.
Fuel pump doesn’t prime so I’ve jumped it at the relay and it’s working well and is getting fuel to the fuel rail.
Checked injectors with a 501 bulb and they are not firing.
Checked injector plug and only has 12v to one side.
The C104? Socket under the inlet had already been chopped off and wires crimped together so I’ve cut these crimps off and redone them to make sure they were good connections.
Unplugged crank sensor and done an ohms check and it’s reading 520ohms which I think proves that’s working fine and as it’s sparking well too?
I’ve opened up the ecu and no signs of any damp or staining etc.
So need some advice as to where to go from here?
Also worth mentioning I’ve joined the 2 green wires behind glovebox to eliminate that.
Thanks

[paultv]

Have you given the injectors a good whack each, ten years could easily be jammed,
just a thought, petrol smell from exhaust?

Paul

[BenHar]

The wiki has this trouble shooting page:

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

Ben

[arrisbmw]

are the injectors clicking, when you turn engine over. fuel pump does not prime, only runs when engine cranks.

get a long screw driver place on injector low as possible ,ear on handle. get someone to crank the engine and listen, you should be able to hear them switching on and off clicking .
you might have to remove them to clean them. after 10 long years they might have got gummed up with fuel lacquer. if there not clicking. try removing the rubber boot to the throttle body and spraying some carb cleaner in ( replace boot ) . even if injectors are not firing engine will run for a short while, on the fuel you,ve sprayed in.

[eko]

No fuel smell and no clicking at the injectors.
Only 12v to one side of the injector socket so need to trace that before confirming whether the injectors are sticking?

[arrisbmw]

i think thats right 12 volts one pin , the other 2 go to ground -.. injectors fire 3 at a time. in two banks,
thats how it is on my 4 pot ( 2 banks fire 2 at a time). sounds like you got to remove them. test individually on bench.
plenty testing cleaning info on youtube. good luck hope you get it sorted.
just a thought you could remove the fuel feed bar and check in car.
12 v across injectors should fire them. you can check the resistant across each injector spec 7- 15 ohms iirc. they should all bethe same. ohms that is.

[arrisbmw]

try the carb cleaner trick , if engine fires, you know its the fuel delivery sys.

[eko]

I’ve had it running on carb cleaner

[arrisbmw]

check wiki, fuel , injectors, dme relay. supplies the power could be the issue

[mcjjordan]

Sounds like ecu is not triggering

Check its getting power
If its got factory alarm ( that sits above ecu) bridge the green wires

Check crank sensor & cam sensor on ht lead

[Brianmoooore]

Checked injector plug and only has 12v to one side.

You sure of this? With the injectors connected? This would mean that the injectors are all open circuit, or that they are all permanently on.
There should be 12 volts on both pins of the injectors with the ignition on, and practically the same with the engine running .
Only with the engine under load should you see a significant voltage across an injector when measured with an ordinary meter.

P.S. Just noticed who I'm replying to! Talk about a name from the past. How you doing?

[eko]

Hya Brian.
Yes I’m well mate,hope you’re keeping well too.
Seems like a ghost town in here now compared to a few years ago. Nice to see you have stayed around though.
Still Okehampton way?
I’ll double my findings on the injector plug tomorrow but fairly certain I only got 12v on one side.
That’s with the plugs disconnected from the injectors.

[Brianmoooore]

If all the injectors were disconnected, then your results are as they should be. They're parallel connected, in two batches of three, so with just one in each bank connected, you should see 12 volts on both pins.
The firing pulses on idle are very short, so you're not likely to see anything on a filament bulb. A LED should respond fast enough, but it'll still be very brief flashes.
If you're getting sparks, it's unlikely the injectors aren't getting their pulses as well, especially if the fuel pump is running when the engine is cranked.
No chance that the two fuel pipes have been swapped over, is there?

Yes, still living the same place, and still (mostly) functioning - just a lot older.

[eko]

Car was a runner when laid up 10 years ago.
Fuel pump doesn’t prime when cranking but I have confirmed it is working by bridging the pins on the pump relay.
Fuel lines are correct way round.
I also tried swapping the white dme relay for a known good one but to no avail.

Glad to hear you are keeping wella‘a

[eko]

I think I’ll just get a proper mood light tomorrow to do it right and confirm for sure.

[Speedtouch]

Sounds like you need a new fuel pump relay at least (or clean the switching contacts inside), and possibly a DME relay...

Also check the engine-to-body earths (brown wires) are all in good order.

[DanThe]

Hi Tony

As Brian said you can use an LED test light to see the earth signal from the ECU or you could use a noid light to see the injector pulse

https://www.ebay.co.uk/itm/Noid-Light-B ... OSwHwZaB1X~

[Brianmoooore]

Fuel pump doesn’t prime when cranking but I have confirmed it is working by bridging the pins on the pump relay.

This can happen will a failing pump (or, in your case, one with some internal corrosion).
When you jump the relay pins, the pump with be getting the full 12 volts+ from the battery, but when the engine is cranking, the voltage available might be right down to 9 volts or so.
Fooled me for a while, many years ago, when I had a fuel pump failure while on holiday in France.