If you don’t mind getting shocked by 40,000 volts, you could pull the spark plug wires off each plug of the cold side. Really? There is a tool for that.
Make sure those plugs are getting spark. Are all your spark plugs wet with fuel?
Alternator output will vary. As the battery charge level goes up, the alt. voltage goes down. Merc electronics are usually stable down to 10volts.
Have you tested the temp sensors according to service book? Hot water and ohm meter.
Starting to sound like you have one or more leaking injectors.
Since rebuild, has the ignition timing been checked?
Hey Tim75,
Sorry it's been quite some time since I've posted. Ive been testing and troubleshooting the boat whenever I have some free time and wanted to bring some good news but I ended up with bad news again. To answer your questions and suggestions,
last time I had the plugs out and checked them firing visually it didn't look like any had a weak spark or didn't fire at all but could have been intermittent so I dont know.
As for the temp sensor I have not tested any of them with ohms and hot water but plan on it even though I'm pretty sure all 3 temps sensors are not the culprit ai would like to confirm once again. I did even up buying 2x used but good temp sensors so I could have a spare to swap just incase though.
The ignition timing has been checked with a strobe and seems to fire correctly since the engine does sometimes run and also have visually checked all the spark plugs firing. What other way is there to ignition time this engine since it's on a crank position sensor and a keyed flywheel to the crankshaft?
This brings me to a segue question which is kind of bizarre to me and hopefully you can answer. Does it matter which of the two plugs for the head temp sensors wiring harness you use on the starboard or Port side of the heads? One has a Yellow sleeve on it and they are both keyed the same. Interestingly enough when I got some life out of the engine or when it finally cleared up and stopped flooding or misfiring I had unplugged the one of the temp sensors on the starboard and the yellowed sleeved temp wiring harness plugged into Port side of the head with the intake manifold temp sensor unplugged also. I would like to know if you could help me understand how these three sensors communicated with the ecm to add or lower the fuel being injected.
Sorry I'm all over the place, but back to the "sounds like you have one or more leaking injectors" comment. You might be right, but what makes you draw up a conclusion like that?
Going back to the alternator which I'm almost positive is over charging or dropping volts at times, here is why I saw its the alternator and I will tie it all together at the end. While troubleshooting in the very beginning and crank the engine when I thought the injectors weren't getting fuel, I did touch the alternator physically and while the heads were cool to the touch because of constant running water the alternator was almost burning. At one point, I did end up putting the volt meter to the battery and as soon as the engine started to misfire or hiccup while running I noticed the battery voltage drop to 6v and back up again sporadically up and down. Now there could be an issue with the alternator if the engine is running but misfiring at a low Rpm which Could draw more power than the alternator can output because it's spinning too slow, but at the time the engine was staying alive so it had to have been at least 900-1100 Rpms.
UPDATE!!: Here is where this situation takes a turn which I thought I had fixed it but then went right back to square one.
This past weekend I ended up swapping the starboard side temp sensor with the one I had purchased and was playing around with the engine with cranking it trying to start it and clearing up some of the flooding. The engine would start misfire or skip then start up run for a bit then when it felt like it just randomly start to misfire and then die again. I'd like to note that when it started multiple times it would run but with excessive smoke coming out of the exhaust and also would like to add that on top of the oil injection I added 1/2 a gallon of oil premix to the full tank of 93 octane I just filled up. I ended up playing with it all day until I got it to idle perfectly and it literally allowed me to put it in F and Rev it pretty high clearing out the smoke. At this power I thought I had fixed it so I drove to the nearest boat ramp and dropped it off in the water to take her for a spin. The results were marvelous. The engine started right up in the water and I was checking everything to make sure it got the proper cooling and such from the "pee-hole" which checked out. I proceeded to take it for a 20 minute ride at different bands of the Rpm without sputtering or misfiring still with some excessive smoke at the low rpms. I did a couple of rippers and the engine was very responsive and would dig into the water and pickup on plane very fast which was a plus. Here is where thing turned ugly. On the way back it was getting dark so I ended up turning on the courtesy lights and the boat navigation lights because it was starting to get dark. As I was putting along at a low rpm, the smell of fuel/oil burnt would start to accumulate along with the smoke coming from the exhaust in the water and then came the misfiring at about half throttle. Three things I noticed on my way back, I would get 4 beeps every 2 minutes or so which didn't effect the way the engine was running when running good and when it started to misfire, I noticed all the lights would flicker as I would try to throttle it in hopes to clear out the flooding or what I thought it was flooding at a low rpm. Everytime I would try to go past quarter Throttle she wouldn't like it and it would start shuttering and misfiring bad along with a very loud continues Beep until I would end up just bringing down the throttle to probably 10% for it to go away. I I'm so sorry for the lengthy story but this boat has taken me on a voyage and I've about had it. Hopefully someone can shed some light, any suggestions would be greatly appreciated.
I have a video of her running outside right before I prepped her to go in the water and also a video in the water doing a stand still full throttle pull if your interested to hear how she sounds.
