Can you reset a Mercruiser ECM?

Espos4 said:
Counter rotating motor on a 1999 boat? That should be easy to verify. Get down there yourself and see which way they rotate while someone cranks the motor.

there’s a good chance that you’ll find they are both standard rotation.
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I'll check when I get home, but I believe we looked at that and one was clockwise and the other counter. I can't remember which was which. If so, at the ECMs still just plug and play?
 
Geoffrey Wallington said:
I'll check when I get home, but I believe we looked at that and one was clockwise and the other counter. I can't remember which was which. If so, at the ECMs still just plug and play?
Click to expand...
I was thinking they should be, because the starter cranks the engine in a certain direction, correct? The ECM just monitors crankshaft and throttle position and tells the injectors when to fire .... I think. I need to do more research obviously.
 
The first step is to find out if you have any codes that have been set. That requires a Mercruiser of Rinda code reader. Both your engines are standard rotation unless you are looking at the props which spin in different directions (controlled by the transmissions).

Generally if you have spark you should also have an injector signal since they are both managed by the ECM. It is possible that something is wrong with the injector circuit but using an injector test light or swapping ECMs between the engines will prove that one way or another.

It certainly seems like a classic fuel problem with clogged injectors.
 
This may be a dumb response and maybe Playdate can correct me if I’m wrong.

If it is the ECM ( I didn’t think the newer boats had them) why not just replace the whole distributor? Trash all the old ECM components and go with a DUI. My old modules went and I was told it could not be reprogrammed. It was cheaper to just trash it and replace with the DUI.
 
dwna1a said:
This may be a dumb response and maybe Playdate can correct me if I’m wrong.

If it is the ECM ( I didn’t think the newer boats had them) why not just replace the whole distributor? Trash all the old ECM components and go with a DUI. My old modules went and I was told it could not be reprogrammed. It was cheaper to just trash it and replace with the DUI.
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Certainly an option if the distributor is the problem but we seem to have conflicting statements.


Just to recap OP's posts:

Changed that and am now getting good fuel. And good spark. But the plugs are not wet at all after all the cranking, so the mechanic thinks it may be the ECM not telling the injectors to open, since the fuel seems to be making it all the way to them.

It is an ok spark, but the plugs are dry after all the cranking, so we don't think it is the plugs. The distributor is clean too. With dry plugs the only thing we can think is the ECM is not telling the injectors when and how much to fire (based on throttle position).

Good advice from Espos4 which apparently has not been done:

Before condemning the ECM, I would check for pulses at the injectors. A test light and/or noid light would confirm whether or not the injectors are being commanded to open.

What happens when you spray carb cleaner into the throttle body?
Does it fire momentarily?

This will tell you in a nanosecond whether your injectors are the problem.


Finally:

One thing the mechanic said to me that made me scratch my head was that the modules were not interchangeable between stbd and port engines, as the motors rotate in opposite directions.

Find a new mechanic.
 
OP has a side mount throttle body with a very large plenum. Carb cleaner idea probably won't work.

Noid light or ECM swap, both simple
 
Definitely looks like a bitch to work on. Still.....a couple of easy diagnostics will tell the story.

6718769_20180606070052475_1_XLARGE.jpg
 
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