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2007 175hp Optimax Won't Start

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bmdale

New member
Hello;
My 2007 Optimax 175 was slow to start a couple of times and now won't start at all. Dribbling gas into the induction system causes it to start and run until it runs out of that gas. So, some of the PCM is active.
Each injector (6 fuel and 6 air) has two wires. It's my understanding that the injectors are supplied with ~12V via one wire and the other wire goes to ground via a 'switch' in the PCM.
It appears all of the injectors are seeing random voltages of less than 1. One wire is, indeed, a low impedance switched lead to ground, the other wire shows, basically, nothing.
I can't find a wiring diagram for this exact model. Similar ones all show both injector wires coming directly from the PCM.
The PCM is getting battery voltage when the ignition is on.
Can we conclude that the PCM is not functioning, or is there a wiring diagram showing something different?
Thanks in advance for any thoughts.
 
bmdale said:
Hello;
My 2007 Optimax 175 was slow to start a couple of times and now won't start at all. Dribbling gas into the induction system causes it to start and run until it runs out of that gas. So, some of the PCM is active.
Each injector (6 fuel and 6 air) has two wires. It's my understanding that the injectors are supplied with ~12V via one wire and the other wire goes to ground via a 'switch' in the PCM.
It appears all of the injectors are seeing random voltages of less than 1. One wire is, indeed, a low impedance switched lead to ground, the other wire shows, basically, nothing.
I can't find a wiring diagram for this exact model. Similar ones all show both injector wires coming directly from the PCM.
The PCM is getting battery voltage when the ignition is on.
Can we conclude that the PCM is not functioning, or is there a wiring diagram showing something different?
Thanks in advance for any thoughts.
Click to expand...
Addendum:
We found a suitable wiring diagram, based upon the color of the wires.
We found that 12V was reaching the injectors, however, the grounding via the PCM did not seem to be working.
We also found that if we kept the engine running for about 50 seconds by dribbling gas in the induction system then the engine would stay running and run very nicely. Of course, when it is shut off it will not start without dribbling the gas in the induction system.
Apparently, there's a 'start' program that hold air injectors open while starting. So, this would mean there's a start program and a run program in the PCM. Looks like the start program isn't working correctly.
Can't find any information on conditions, sensor readings for instance, that would stop the PCM from cycling the injectors.
Any ideas appreciated.
 
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