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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3342
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2006 mercury verado that won't start. I check the

Customer Question

I have a 2006 mercury verado that won't start. I check the spark plugs and they're all firing. I removed the fuel rail and observed that only the lower three injectors were firing. I also noticed that when initiating the start sequence the top three (sometimes) would fire once and stop. The lower three would continue to fire as normal. I connected the CDS and did an injector test and all passed. Also, the crank shaft position sensor and the cam shaft position sensor we're changed. The computers on the engine was also changed. Continuity checks were also done on the Barnes for the wires connecting the injectors to the computer. I'm pulling my hair out on this one. One more observation that was made was an "ignition fault on the smart craft display. However , I could not get the fault to replicate when it wasn't there and I couldn't get it to go away when it was. The engine ran perfectly when the fault would throw.
Submitted: 1 month ago.
Category: Boat
Expert:  Charles replied 1 month ago.

Hello, my name is***** will assist you.

Expert:  Charles replied 1 month ago.

I have a few questions back for you.

Has any work been done to the fuel system?

Is there a primer bulb in the fuel line?

What is the fuel pressure going to the rail?

Are the coil original or have they been replaced?

Customer: replied 1 month ago.
1. The fuel pump (fuel supply module) was replaced. 2. There isn't a primer ball. 3. Not sure of the exact fuel pressure but when the valve at the top of the rail is opened fuel shoots out like a fire hose. In my opinion fuel pressure or any other fuel parameter wouldn't be the issue here given that, as I mentioned, the fuel shoots out from the top and also only one injector is opened at a time so the fuel pressure, no matter what it is will be constant at every injector. 4. The coils have been replaced and since replaced, months ago, the engine has been working perfectly.
Expert:  Charles replied 1 month ago.

What was the ignition fault that the gauge was showing?

Which pump was replaced, or was the entire FSM replaced?

Customer: replied 1 month ago.
The entire fsm was replaced. As for the ignition fault there wasn't any details just a message saying "ignition fault".
Expert:  Charles replied 1 month ago.

There were a few bulletins on this engine when it came out. Check the ground bolt for the engine. Make sure that the rung terminals are not cutting into the harness that is running under it. Also look at there the wires for the CPS gone from the harness going to the sensor. They have been known to chafe there as well. Let me know what you see.

Customer: replied 1 month ago.
The CPS sensor was replaced with a new one. I will check the grounding bolt. I'm assuming your talking about the one that's on the Stbd side of the engine fwd of the computer.
Expert:  Charles replied 1 month ago.

Yes that is the one. On the CPS, it is not the sensor end of the plug, it is the harness side right around the starter

Customer: replied 1 month ago.
Gotchya. I'm going to check that out in the morning. And thanks, ***** ***** appreciate the help.
Expert:  Charles replied 1 month ago.

Your welcome. Talk to you then.

Customer: replied 1 month ago.
I just got off the boat. I don't see any chaffing and the ground wire looks fine. Here's some pics.
Customer: replied 1 month ago.
Ground
Customer: replied 1 month ago.
CPS wife shot
Customer: replied 1 month ago.
CPS close up
Customer: replied 1 month ago.
What's baffling me is the fact that only three injectors are having issues.
Expert:  Charles replied 1 month ago.

Look at the rear ground post. There is one of the rings that is poking into the harness loom. Make sure that it is not cutting into a wire.

Customer: replied 1 month ago.
I checked that. I didn't see any chaffing anywhere.
Expert:  Charles replied 1 month ago.

Would be more of a cut into the wire.

Have you looked at the ground bard located behind the ECU. There are a few of them there.

Customer: replied 1 month ago.
Bard, not sure what that is.
Customer: replied 1 month ago.
Remember though I was able to fire each injector individually using the cds. They all fires perfectly.
Expert:  Charles replied 1 month ago.

board or multipin grounds. You will see them begind the ECU. Many wires going into a long flat bar. The cap comes off to look at the bars between them.

Customer: replied 1 month ago.
Oh. I know what your talking about. I will have to check that tomorrow.
Customer: replied 1 month ago.
Is that also known as the splice group?
Expert:  Charles replied 1 month ago.

In the book, yes I think so.

Expert:  Charles replied 1 month ago.

Did you do a cranking spark test or on the CDS?

Customer: replied 1 month ago.
On the CDS
Customer: replied 1 month ago.
All 6 injectors worked.
Expert:  Charles replied 1 month ago.

Try a cranking spark test on the coils.

Customer: replied 1 month ago.
Did that. Plugs spark.
Expert:  Charles replied 1 month ago.

Ok

When did the engine run last? And what did it do right before it shut off?

Customer: replied 1 month ago.
The engine last ran about 3 weeks ago. Nothing out of the ordinary happened before it was last shutdown. Two days after I went to start it and from that point it wouldn't start.
Expert:  Charles replied 1 month ago.

Is there a primer bulb in the fuel line from the boat to the engine?

Customer: replied 1 month ago.
I there isn't.
Expert:  Charles replied 1 month ago.

Ok, I know that you have replaced the FSM, but have you tested the fuel pressure to the fuel rail?

Customer: replied 1 month ago.
I haven't hooked a gauge up to it but when the valve is opened fuel shoots out like a fire hose. Also, note, the lower injectors are spitting fuel just fine, it's the top 3 and for some reason the injectors aren't opening.
Expert:  Charles replied 1 month ago.

Have you tried a niod light in the upper three injectors to see if the signal is getting there?

Expert:  Charles replied 1 month ago.

I am assuming that you have already looked at the easy stuff like the fuses

Customer: replied 1 month ago.
Niod light?
Expert:  Charles replied 1 month ago.

You plug it into the plug in for the injector, then crank the engine over and see of the light will flash or not.

Customer: replied 1 month ago.
Fuses are good. I also checked for the same volt readings across the injectors. All were good
Expert:  Charles replied 1 month ago.

Have you swapped the three working with the three not working?

Customer: replied 1 month ago.
Expert:  Charles replied 1 month ago.

And still not working?

Customer: replied 1 month ago.
Negative.
Customer: replied 1 month ago.
Like I said earlier, an injector test was done from the CDS and all injectors fired.
Customer: replied 1 month ago.
Also, once the start sequence is initiated the top three injectors in question would sometimes spray (open/fire) once. as the sequence continues only the bottom 3 will continue to spray.
Expert:  Charles replied 1 month ago.

Alright, when you tested the voltage going to the injectors, was that at key up or cranking? Where was the ground lead of the meter for that test?

Customer: replied 1 month ago.
Hmm...
Customer: replied 1 month ago.
Key up.
Expert:  Charles replied 1 month ago.

What about the meter leads?

Customer: replied 1 month ago.
What about them. The leads are good. Tested them on another source.
Customer: replied 1 month ago.
A known working source.
Expert:  Charles replied 1 month ago.

I mean where were they connected to the harness when you did the test.

Customer: replied 1 month ago.
Oh. Ground was to ground and the red lead was to the red wire on the injector wires. Tested it from the inside of the connector.
Customer: replied 1 month ago.
Actually, no. What I did was test for continuity between the injector red wire and the plug on the alternator. Looking at the schematic I observed that this is where the plugs get their power from and that's only when the alternator is engaged.
Customer: replied 1 month ago.
They all checked good.
Expert:  Charles replied 1 month ago.

Can you have a helper crank the engine while you test the upper 3 injectors electrically? Like you did for key up. This is really sounding like an issue in the harness.

the PCM controls the ground side of the injector to fire it. Follow the diagram from the ground on the injector to the PCM, check all of the break points in the harness. There has to be a bad wire there. You can test resistance from each injector to the PCM plugs using the diagram to tell you which pin in the plug you need to be on.

Customer: replied 1 month ago.
I did I fact check the connection between the injectors and the PCM. Everything checked good and also remember the CDS injector test. It fired all injectors.
Customer: replied 1 month ago.
This is what's baffling me. It's like the pcm is not telling the injectors to fire. It will do it once at the beginning of the start sequence but that's it. As the engine continues to crank only the bottom 3 will cost continue.
Expert:  Charles replied 1 month ago.

Does the engine even try to fire at all? It should run on 3 cylinders.

Customer: replied 1 month ago.
Once in a while it would kinda have a tough start for about a second.
Expert:  Charles replied 1 month ago.

Have you looked to make sure that the throttle body is not loose on the superhcarger?

Customer: replied 1 month ago.
I didn't. I will check that. I don't see how that would stop the injectors from working.
Expert:  Charles replied 1 month ago.

I am wondering is that is secondary to the engine not starting. Since you have already tested the harness, and swapped the PCM, there has to be a different cause.

Customer: replied 1 month ago.
The only thing is that when removing the fuel rail from the engine and observing it during the start sequence you can see that the top three injectors are not spraying. While there might be another issue helping with the engine not starting what I do know is that there is an issuer with the injectors.
Expert:  Charles replied 1 month ago.

Yet, since you have tested the voltage going to them when cranking and it is good, the problem lies elsewhere.

Customer: replied 1 month ago.
No, I haven't tested them while cranking. I will have to take your advice and get someone to crank while I test.
Expert:  Charles replied 1 month ago.

Great. Let me know.

Customer: replied 1 month ago.
Will do.
Expert:  Charles replied 1 month ago.

Talk to you then.

Customer: replied 1 month ago.
Hey, morning. Sorry for the gap in communication but I was tied down with some other things the past few days. I have to charge the batteries on the boat so I'll get to that sometime today. When done I will go ahead and continue to trouble shoot. I will get back with you tomorrow and let you know what came about.
Expert:  Charles replied 1 month ago.

No worries. There are no time limits here.

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