urgant help needed with ABY not starter

[s0_big]

If I understand right. You have 12V at both pins on the injector connector? Are you measuring DC and from engine earth to connector (from valve cover bolts)? The injector gets power from a relay inside the ECU before start. When cranking/start the injectors also get 12V from the fuel pump relay (if it pulls). The ECU only puts the earth to the injector that should open. Earth to the injectors is taken from earth points on the intake manifold I think.

[flat out 90]

Ye I think iv been over thinking it

[Henkjan]

If I understand right. You have 12V at both pins on the injector connector? Are you measuring DC and from engine earth to connector (from valve cover bolts)? The injector gets power from a relay inside the ECU before start. When cranking/start the injectors also get 12V from the fuel pump relay (if it pulls). The ECU only puts the earth to the injector that should open. Earth to the injectors is taken from earth points on the intake manifold I think.

and so with the ECU not pulling to earth, it is normal that both sides of the injectors measure the same voltage. open circuit -> no current -> no voltage drop

[Henkjan]

https://www.ecmweb.com/cee-news-archive/electrical-theory-part-1

[flat out 90]

Ok so iv looked at all the earths the engine all senders and the ecu are all earthed has they should. So just out of interest I put the volt meter on the signal from the hall sender and put to earth and I get 5v has soon has I turn the ignition on. So removed the pin from the plug and did it again and it’s 5vs coming out of the pin from the ecu. Now I know the ecu is a good one has iv just been and had it on another car and it starts and runs fine. So iv ruled that out. Correct me if I’m wrong but with the pin removed from the plug I shouldn’t be getting anything out of it.

[flat out 90]

All so last night the ecu was getting warm all the time. This may be one of those things but the central locking has stopped working two.

[flat out 90]

So if I pull the 6 pin black plug of the bottom of the fuse box it loses its power but is that because I’m killing to power to everything. Is it possible the fuse box has had it

[flat out 90]

Ok so now iv managed to look at the wiring diagrams I see where iv been going wrong. So iv tester the ecu works on another car no problem at all. What iv changed for known working with no joys

fuse box
all the relays
hall sender
crank sender
starter motor
ignition switch

im getting kind of desperate now so any ideas would be helpful

[jeffstoo]

I know this may be a silly question as if it has you would have probably checked it out early doors but has the car got an alarm/immobiliser? I had a situation where my car would turn over but not start . I had power to the fuel pump but no spark, thought it was ignition switch so bridged two terminals on ecu ( can't remember which at the moment ) and away she went. Fitted new ignition switch and still the same. Turned out to be the immobiliser which was connected to three separate circuits, ignition, starter and fuel pump.

[flat out 90]

I’m willing to check anything but if it was that I can’t work out how it would bump start but not start when you turn it over with the key.

[hermanio]

post a video of the no-start. are the batteryterminals clean ? try running a new ground cable from the battery to the chassis.

[flat out 90]

Ok so tryed a new earth one to earth on body and one direct to the engine still no look at all just turns over but will not fire doesn’t even try

[LHD_Kid]

Not sure what I am missing here, but the only difference between bump starting and key starting is the starter motor?

[flat out 90]

The car turns over fine on the starter just won’t start. But when you bump it it runs like a dream.
it won’t spark and won’t fuel. When turning over.

[simons2]

Am I right in assuming that the ecu has to see up to 19 rpm from the G28 before starting but once running uses other sensors to stay running? If so do you think bump starting might show the ecu way more than the required rpm hence tricking the ecu into thinking the engine is running via the other senors ?