HI- I will explain the whole thing---because its important to know the sequence of events. I started like many other times- except this time I filled up the tank- 40 gal- it was probably down to about 10 gal so I put in about 30 gal. I got to the lake- and went thru normal routine- wife in boat, I back it in on ramp, she starts it and pulls to dock while I go park. She was having some trouble starting it- and when I got down to the dock- I jumped in and it started--but not like normal- but once it was started- we took off and at WOT- it was fine. I just assumed that it was some kind of issue with the fuel level getting low, or the bulb losing pressure- or ---I didn't know.
I get home and first thing I did was to check the plugs--gap, clean/dirty etc- and decided to replace them. I did as well as change the red fuel filter. I also read about the fuel hose lining breaking apart and getting into the system- (I had the grey mercury hose) so I changed it with a new one which was a Sierra or mercury---I dont recall but sure enough- my hose I could see the inside lining was separated from the rest of the hose. So- I thought- a filter and hose will fix this.
I ran the motor using a big tub I bought at a livestock place---and it was still running rough. So, I went to the local mercury place and bought the fuel pump kit- (the one external to the VST), the parts to rebuild the VST internally, and did that. The VST had this goo in it- about 2" deep- and it was crusty on the sides---I assume from sitting for a few years after my brother died unexpectedly very young--3 months after buying it- we bought it together but he went in and signed papers so it was in his name---so it took several years to resolve that--so this motor probably had less than 25 hours on it when I finally got it back last year about this time. I had never had a problem in the 25 or so times i took it out until that day--that I coincidently bought gasoline. The other strange thing- is that while it was in storage while his estate was in probate, I had the motor "winterized" and serviced about every 9 months- a mercury tech- would start it, check oil in lower unit, and basically just make sure it was safe to store and it didn't sit without running for years and years. So, assuming this was done PROPERLY---especially after I had ran the motor so many times- all day sometimes without any problems- I have no idea how or why that goo was in the VST. From now on, I will check it every few months (until I am confident its OK). I always run star tron ---I think the fuel preservers are all the same, but I dont mix them- I use the same one only because I dont want a chemistry experiment going on inside my gas tank.
Anyway after the filter, fuel pump, hose, and VST service- It still ran rough. I checked the coils- both with spark tester and with ohm meter - and by disconnecting one at a time while it was running- and all 3 were good. I sent the injectors in for cleaning/service to a marine injector place. Got the injectors back and when I hit the key, it roared to life--like in the old days- but then started the rough idling and stalling a minute or so later.
I changed the poppet and t-stat- cleaned out the water strainer which had a bunch of grass in it- and checked the pressures. They were not exactly 10 psi different but were like 13-14 psi different. I did that because I was servicing the motor- and had never done those things- so did them just so I could check them off the list but also didn't really know what else to do at this point.
I got a 3 gal tank from amazon- and put new premium gasoline in it- and tried that- same thing.
I changed reeds- and once again- it roared to life- but then started the idling/stalling issue. The reeds were perfect but I changed them anyway, and the injectors---those 2 things did make it run better but did not fix it. Chris Carson- he told me, "if you are going to check the reeds, just change them, then you dont have to be worried about them and they are too much work to check---only to have to change them later"---and he was right---its a giant hassle to get to them mostly because of the oil tank. I am glad I took his advice.
So, now- assuming the ECM is good, and there isn't some strange hose or wire problem somewhere, I am back to square one. I started with the coils----but this time around- the bottom coil now didn't seem to make any difference hooked up or not- the other 2 yes, it would barely run if one of the other 2 were disconnected- Now I know why---even though that bottom coil had the same amount of spark (my spark tester is one of those ones you can adjust the spark gap- and I could make the gap about 3/4 inch--and that was where all 3 would cease to make the arc---also, according to the mercury TSB Bulletin No. 2007-25R2- all the measurements with ohm meter were perfect on all 3 coils. The reason why it would barely run with one of the other 2 coils unplugged is it was running on 1 cylinder.
I got another coil- and replaced the one that seemed to have little/no impact if it were connected or not- and that fixed it. Obviously that coil is breaking down somewhere and it only fails under load and just enough to cause problems, but not enough to test bad. If I gave you this coil- and you tested for spark, and measured the spark, checked with DVM, and also inspected it visually you would think it was a new coil.
So, I ordered a new coil- and will most likely buy 2 more- and change them all.
These new coils with semiconductors buried in epoxy break down and start failing causing very strange problems. Its a very high voltage spark, with very short firing time- coupled with heat and vibration---it makes perfect sense to me now.
My outboard ran perfectly wot- full RPM, full speed, but it didn't idle right and it kept stalling (on idle only). Which means that it was just good enough to run, but not good enough to run perfectly.
So be warned- if you have some very strange - unexplainable problem and you have checked everything else- I would get a known good coil and one by one try it in each position. Spark testing, DVM testing, all are a waste of time. I see others with these strange- seemingly unsolvable idle/starting problems, "I have been to mechanic many times, and they cannot figure it out"- "I am at a complete loss"--just like I was- and I wonder how many of them might be an intermittent coil or coils.
The other thing---I found out that many racers use these exact same coils--GM LS1 LS2, LS7 engines----"1300 HP supra"--I had a supra once, and I didn't know it could be pushed to 1300 hp- but whatever- they use these same coils. I found out cross referencing the part number, and then by asking these race parts places or the race car builders- and that many of them KNOW that the coils they use are made in the same factory as the merc labeled coils and -- they have the same engraved numbers. They are about 1/2 the price---also, these race car people say "we have never had a complaint or problem with (our) coils ever"-----so before i spend 130$ each for 3 or 6 of the mercury coils----
Obviously Mercury does not want this information out---if you doubt me, I can give you names and # of people who are highly respected in the race car world- who build or drive these cars--(or sell parts) and they will tell you exactly what I am saying. Also many ATV and snowmobiles use these same coils. Polaris for one, Sea Doo for another. I dont know if all their machines ---I dont know anything but I know that some of them use these same coils. But those (ATV/snow machine) coils are about the same price as mercury coils.
I wouldn't use the 25$ chinese ones- but the mercury ones are 130$ and made in china too. If I can get a set for 50-60$ each, from a source that supplies 1000+ horse power race cars and they stand behind them----why not? Mercury (who I called about this) and dealers---does absolutely NOTHING, and the mercury parts place will not exchange or return---if you were to buy one that was DOA. These car people are very friendly and helpful--and they stand behind their products. Its a huge difference- pay 1/2 the price, get the exact same thing, and they stand behind it?
If you want one in a mercury box---i understand and wont be critical of that decision. But if you want one in a different box, but it has the same engravings and is 1/2 the price- AND they stand behind them? Please dont be critical of me. I have no issues whatsoever with the local independent mercury repair place- except that they are very backlogged, and mercury charges very high prices for some of these parts.
Thank you so much to everyone who helped me. I was very stuck--and very frustrated--and honestly did not know what to do. I had this motor checked on the mercury tester (for 150$)--and there were no codes, no failed test, no nothing. I was told that "we can fix it- but I can't even begin to tell you how much it will cost until we get into it"----and while I understand that- I was not prepared to write a blank check until I had at least done the basics that I was able to do---AND---they couldn't even promise a time frame--they said that it would be a month before they could start working on it.
Cabelas- didn't even have a mechanic--they all quit (supposedly)---I asked them first- "can I get a diagnostic test"---it was 99$. And I was told, "call me next week and I can see when I can schedule it"---so i asked why not schedule it now? I was told, "we have no techs---our last one quit so I am hoping to know when I will have a tech-so call me next week"---forget that.
thank you again--I really appreciate all the help. I would probably still be going in circles without it.
