Mercruiser 4.3 injection without any ignition

[stresspoint]

i have followed this thread since start , has the battery been load tested .

reason i ask , today i went to start an ATV , battery showed 13.2 v but it would only click the solenoid , hooked up a jumper pack and fired immediately..

? have you pulled the starter motor to check for rust on the shaft , this can stop the drive from spinning out and you just get a clicking .

 

[alldodge]

Your slave solenoid is bad

Having less then 5V on the Gray to Blk/Pink means one of the sensors is pulling to much current or the ECM has an issue. With key ON, disconnect the CPS and see if 5V comes up. If it doesn't reconnect the CPS and one by one disconnect the seawater pressure, oil pressure, and ECT

 

[navigateur29]

Hello,

stresspoint:
battery voltage is 12.90v
when I do a direct connection of slave connections
engine is cranking correctly and I can try several times
so battery seems correct and I tried with 2 different

alldodge:
I think so that the slave is bad :-(
re is i
concerning the +5v all grey wires go to the "slice 101"
I suppose there is a 5 volt power somewhere but I can't find
any information in docs about it...

yes good suggestion I already disconnected CPS sensor when I did
last measures/tests
so this one is not suspected for a possible high power consumption
but I will try with the others

I would also like to check the 5V power supply but where is it?
I don't think that all sensors +5v go to the ECM
There should be an external source for that

thanks ;-)

 

[navigateur29]

sorry I check back the full electrical sheme from ECM555 doc
I followed each grey wire from commun slice101 and
there is one connection to ECM pin 18 !
then I can first disconnect ECM connector and check if +5v is correct
otherwise ECM is bad :-(

will take you informed ;-)

 

[alldodge]

Pin B-18 is splice 102 which is 12V key ON
Pin B-21 is splice 101 which is 5V

The water pressure sensor is on the power steering cooler

 

[navigateur29]

Hello,

I solved 2 issues today

First one: slave solenoid issue
when we turned the contact key to start the engine
there is +12V to the slave solenoid
Ground is also ok
we were able to crank with a direct cnx of slave contacts
so it confirms what was already suspected --> slave solenoid must be replaced

Second one: 1.7v instead of +5v in CPS sensor connector
I first checked the voltage on the CPS connector and it was +1.7v
Then as it was told me in this thread, I disconnected all sensors one by one
and no change always 1.7v on the CPS connector




Then I checked the voltage on the oil pressure sensor
and I had a big surprise: +5.02v!!!!




So I believed that there was a problem with +5v (grey) or ground (black/pink)
wires of the CPS
To determine which one was bad, I cross +5v & ground between oild sensor (reference) and CPS (faulty)






after these steps I was sure the problem was relative to grey +5v wire of CPS sensor
I wanted to check the resistivity step by step and I fist connected my "wire piercing probe" to the grey wire of CPS just before the connector
to be sure of the correct contact I let the multimeter also connected to the ground of oil sensor and I measured +5v!!!!!!!



conclusion?
There is something wrong inside the CPS connector on grey wire
metallic contact surface seem ok but instead to deliver +5v the contact
delivers only 1.7v :-(
impossible to repair it
so I ordered a new one and will replace it next week-end

I will show you what will be done and also will tell you if it solved our ignition problem

I took time to post details with pictures to thank all your valuable help
hoping that now this procedure may also help somebody else
to check any other sensor in case of +5v issue

many thanks to you ;-)
will take you informed of next week-end tests....

 

[alldodge]

Very nice write up, thank you

 

[QBhoy]

Hi. See the crank position sensor you mention…does that have a yellow weather cap on it there ? Hard to make out. Yellow caps on these mpi plugs normally mean a terminator resistor. A purple weather cap is what it might just should have had. Where is that plugged into ? Presumably not the distributor? The mpi distributor (although it has a plug port) shouldn’t generally have anything plugged into that port at all.

 

[dubs283]

Hi. See the crank position sensor you mention…does that have a yellow weather cap on it there ? Hard to make out. Yellow caps on these mpi plugs normally mean a terminator resistor. A purple weather cap is what it might just should have had. Where is that plugged into ? Presumably not the distributor? The mpi distributor (although it has a plug port) shouldn’t generally have anything plugged into that port at all.

Terminator resistors are for the CAN network wiring/connectors. OP is having a 5v ref issue on the main engine harness, completely different wiring/connections.

Sounds as though OP has figured out the CPS connector on the harness side is the issue. These are Delphi GM connectors and are repairable/replaceable. Local auto parts store should have connectors/repair kits available

 

[QBhoy]

Terminator resistors are for the CAN network wiring/connectors. OP is having a 5v ref issue on the main engine harness, completely different wiring/connections.

Sounds as though OP has figured out the CPS connector on the harness side is the issue. These are Delphi GM connectors and are repairable/replaceable. Local auto parts store should have connectors/repair kits available

Yeah. Definitely aware of that. But just pointing out that it may be the wrong set up altogether. And definitely for certain…there should be not plug inserted into the port on the distributor base on that engine. Maybe it’s not plugged into it…but worth a mention

 

[navigateur29]

Hello,

alldodge:
thanks
I always do my best to return the help that I have been provided ;-)

QBhoy:
you are right to point this out!
we don't what the previous bad mechanic did exactly
and for sure he didn't know himself what he was doing...
I checked back the docs and yes for this engine
we shouldn't have any connector plugged on the distributor

I don't remember if there is or not but
I will keep your valuable remark in my head for next tests
thanks ;-)

dubs283:
We ordered in an automotive shop the same connector with wires
I will cut the wires and solder the new connector with thermo sheath
even if its not the same colors on wires doesn't matter it will be possible
for next guy that will need to check to see old/new colors ;-)

should have connector + slave solenoid by next week-end

thank you for the help