PCM H6 sputtering under load

[Speedy]

No... most likely the shorted battery or possibly the battery switch


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[zmnypit]

Spent all day tracing wires yesterday and no bad spot found so not sure about a short. Ordered a new 125a fusible link cable, alternator and fuel/water separator. Hopefully it comes soon so I can get it back together and test. Will keep posted

[zmnypit]

Well after FedEx screwed me all weekend I finally got the alternator and fusible link today. Got both replaced along with a new battery replaced and still sputtering over 2500rpm. Ive got a video I'm going to upload to YouTube and post in a bit. It's more of a popping sound/sputter so I'm not sure at this point. Dealerships are backed up not to mention it's 2hr away one way. Once the rain stops I'm going to pull the sparkplugs and check those. One other thing I'll mention is it's very hard to start. It took 2 full cycles of pressing the start button and not starting before it started on the 3rd attempt barely.

https://youtu.be/JzF4zu_tgek

[Speedy]

Is the voltage back to normal? If so, that means that one of the two problems is fixed. The sputtering could be a misfire from one of the cylinders


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[Speedy]

I have think about this one. (Misfire under load)


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[zmnypit]

Is the voltage back to normal? If so, that means that one of the two problems is fixed. The sputtering could be a misfire from one of the cylinders


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Yep.. getting 14.2v on the dash and on the back of the alternator using a multi meter. You can rev to about 2500rpm and that's all it will do before popping.

[Speedy]

At least one thing is fixed. What year and model is that boat? Is the check engine light on?


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[Speedy]

G23


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[zmnypit]

G23


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2017 G23, pcm H6 no ses lights no codes stored

[Speedy]

I have seen and listen to the video multiple times and I can’t think of what could be wrong.
I thought it could be a misfire from the ignition coil or spark plugs but then that means that it should also misfire at idle but based on the video it runs smooth at idle. Which leads me to believe that it could be fuel related.
I feel kind of bad because I was only able to help you with the electrical problems


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[Speedy]

I sent your video to a couple of friends of mine with a lot of experience with Chevy motors, they really believe that it’s a misfire. I definitely don’t want to steer you in the wrong direction but in this case this would be my most educated guess. I’ll PM you my telephone number so that I can walk you through checking for misfires.


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[zmnypit]

I sent your video to a couple of friends of mine with a lot of experience with Chevy motors, they really believe that it’s a misfire. I definitely don’t want to steer you in the wrong direction but in this case this would be my most educated guess. I’ll PM you my telephone number so that I can walk you through checking for misfires.


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I'll try anything at this point. It's raining so be a bit before I can go back out and look it over

[zmnypit]

Was going to check fuel rail pressure this morning but this may be a bigger task than I envisioned. You cant see the rail/injectors at all. I'm trying to find a H5/H6 service manual now to see exactly where the schrader on the rail its located. I see in the technical manual pressure should be 55-62psi but doesn't show the rail. Verified both pumps are running by disconnecting one at a time then pressing the start button. Both pumps you can hear prime but that doesn't mean anything.

[zmnypit]

Never could find a way to test rail pressure as you cant see the rail/injectors. I took the FCC off and drained it. Went ahead and ordered a HP fuel pump and filter as $200 is easier to replace then trying to find the fuel rail it seems. If it doesnt fix the problem I'll have a spare. I know the FCC is filling as it was full as well as the water separator so I assume the Low pressure pump is ok but who knows at this point.

[zmnypit]

Quick update. FedEx has lost the high pressure fuel pump as well as the FCC filter so be a couple more days before I can replace those. Just finished siphoning 53gal of gas out of the tank and put 10gal of fresh fuel in along with new spark plugs and water/fuel separator. Same hard start issue same popping over 2500rpm. Ran for less than 10min on the hose and plugs are already black.