Mercruiser/Motorola versus Stand Alone ECM's

[njh1]

Hi...thanks for that.
I have tried the earth route but it wouldn't start. I will try again.
What is the DLC connector?

 

[alldodge]

Data Link Connector, it has 4 pins and is where a scanner is plugged in

 

[njh1]

Ahhh...awesome thank you.

 

[njh1]

Going in...

 

[njh1]

no power to the only ecm blk and ppl i can find...nor to the dlc ppl

 

[njh1]

sorry, that should be Blk/Pnk to the ECM.

 

[njh1]

 

[njh1]

Is this the dlc

 

[njh1]

I only get either 12 volts coming down the Ppl/Dk Grn or 7volts down the purple in the picture and to the ECM at pin 18.

 

[alldodge]

Yes, that's the DLC
The B18 (purple) comes from the key

Go the key and check for 12V on the purple wire when key is ON
If good check the boats kill switch

 

[njh1]

Right...a quick update.
Ignition cut out switch had disconnected itself in the middle of all this...reconnected it and I now have 12 volts on the purple wire at the back of the ECM and at what i think is the DLC, and 12 volts on the MPR link/signal wire to the ECM.
I do not have voltage at pin 1/Ppl/pnk.
Does the 5volts for the water pressure sensor etc come from the ECM?
Thanks for the help...

 

[alldodge]

Yes 5V comes from the ECM
When you turn the key ON now does the fuel pump turn on?

 

[njh1]

no it does not...

 

[njh1]

Is there a splice here i may have bypassed?
I had to put a fresh wire in to get the solenoid to trigger from the key.

 

[alldodge]

Fresh wire connecting where to where

 

[njh1]

the red and yellow from the key.(bearing in mind the is no digital display on this boat) to the starter solenoid, bypassing the 10 pin harness connector

 

[alldodge]

The key has 3 wires
Red/purple main power from 50 amp breaker, thru 20 amp fuse
Purple
Yellow/Red start thru neutral safety to slave relay on motor

 

[njh1]

Yep then thats ok...
When the ECM that came with the engine didn't work we did loads of tests and came to the conclusion that the ECM isnt giveing the mpr an earth. I've wired in an earth and the mpr fires but doesnt trigger the fuel relay as it's earth also comes from the ECm.
We have now checked voltage through the ecm and it is present by connecting to the relevant pins Purple In (12v) and Black out grnd
We have another ecm that I bought but am trying to dend back as it doesnt say its for a 5.0 v8 mpi but the seller assured me it was so I have pluggsd it in and it goes one stage further and supplies the 5v to the injectors etc but still doesn't trigger the mpr...
I can trigger the MPR and the fuel Relays by prviding them with an earth and the pump runs satisfactorily but there is still no spark.
Bit stuck now. 2x duff ECM's

 

[alldodge]

The injectors should have 12V on them (Pink/White from fuse). With key ON the 12V should be present and they are turned ON/OFF with a ground from ECM

For injectors to fire the ECM needs to see a signal that the distributor is firing

All that said, I'm thinking there is something disconnected or a blown fuse

 

[njh1]

Could i use the same ground lead to the ecm for all three?
And can i check that the distributor stays disconnected...there is a plug and socket that match but everything Ive read say it's not used...