Had boat in water first time today

[Bradmxz]

Hey guys like the title says the wife and I had the boat in the water for the first time today. Needless to say it was less than stellar. This being our first boat were newbies to this. And if you could see the way we loaded the boat back onto the trailer I wouldn't have to say it. Anyway now I'm in need of some real help. First the engine idles like a dream in the driveway I can let go of the throttle cable and give it a few pumps by hand and seems flawless. But once we put it in the water and shifting into forward it would sometimes backfire and stall. The majority of the time it done this. I was thinking a fuel problem so as soon as we got home I took the carb off and am picking up a carb kit Monday. But if I hold the choke open with my finger and push the throttle there are 2 steady streams of fuel injected. So could this be an air problem. I will be rebuilding the carb anyway now that it's off but it seems to act as it should. What about the flash arrestor. Is there anything I can do with that short of buying a new one to see if it's working as it should. The engine serial no. Says 94 on the cover, 3.0l 130hp engine.

Now for the second problem. When it didn't die out it seemed to work pretty good as far as running but the tach wouldn't climb any higher than 12-1300 rpm at full throttle. I never really noticed if it sounded faster than that and maybe I have a bad tach. But I know it should reach 4200/4800 rpm. Any help now is very appreciated.

 

[flipbro]

The stalling issue is more then likely the shift cable being worn or out of adjustment. The other problem did it get up on plane? How fast did it travel? 1500 rpm you wouldn't plain and wouldn't be traveling too fast.

 

[Bradmxz]

Excuse the newbie but I'm not sure if it did get on plane. Seemed to be going along pretty good but nowhere near what it should be

 

[alldodge]

We need you engine serial number
I wouldn't suggest rebuilding the carb just yet. Start by checking compression of the motor.

Need to check timing, should be
1 BTDC for serial number 0L096999 and below
1 ATDC for serial number 0L097000 - 0L00340999
2 ATDC for serial number 0L341000 and above

Also to set timing it needs to be in base timing mode

 

[Bradmxz]

Ok will check compression asap. I don't own a timing light so is there any other way to check it. Also I'll do if I can upload a pic after on my distributor there is only one white wire and its looped right back into the plug on the distributor. I only know cause I searched for checking timing on 3.0l merc and it says to jump the 2 wires from the shift interrupt switch

 

[alldodge]

Ok will check compression asap. I don't own a timing light so is there any other way to check it. Also I'll do if I can upload a pic after on my distributor there is only one white wire and its looped right back into the plug on the distributor. I only know cause I searched for checking timing on 3.0l merc and it says to jump the 2 wires from the shift interrupt switch

With only one wire coming from the distributer you must have points. What year is the boat?

If your boat has points your timing should be at 8 BTDC and the dwell should be between 39 and 45

 

[Bradmxz]

No it has electronic ignition. I can't upload a pic from my phone. Says file size to big. will post with serial no. First thing in the morning. My boat is a 1990. It had a 4.3 l in it I removed it and put in a 3.0l. The serial number on the cover(if it is the right cover) says between 92 and 94 I think but I will post it as soon as I can

 

[flipbro]

No it has electronic ignition. I can't upload a pic from my phone. Says file size to big. will post with serial no. First thing in the morning. My boat is a 1990. It had a 4.3 l in it I removed it and put in a 3.0l. The serial number on the cover(if it is the right cover) says between 92 and 94 I think but I will post it as soon as I can

Why did you put a 4 cylinder in place of a 6. Your probly under powered.or gear ratio is off. Did you change drives?

 

[Bradmxz]

my main concern was fuel. The chart I seen on a mercruiser website claimed the 4.3 used 12 gph at 4000 rpm. The 3.0l was claimed at 7 gph. Sorry but I'm not a Rockefeller. Owning a boat is something my wife and I talked about for a long time and at that rate of fuel consumption that's all we would do is own it. The 3.0l is not easy on fuel either but it's much better than the 4.3. Plus the 4.3 that was in it was toast and needed rebuild. At least this way we will be able to enjoy it. Power is not a major concern right now. This is our first boat and we just want to get into it. Even though our first ride in it yesterday wasn't great. We still had a good time because it's something we done together. Now we just need to work the bugs out.

 

[Rick Stephens]

You need to learn a bunch of things to tune your boat properly - first is getting the ignition right - and then getting the prop right. The bigger V6 used a higher gear ratio drive. If you are using a swapped in 3.0L motor with the V6 outdrive then you need a lower pitch prop to compensate. You are lugging the 3.0L down enough to damage the motor running it too high geared. Prop pitch is determined by Wide Open Throttle (WOT) RPM of the motor. At WOT you want the engine to be running at between 4600 and 4800 RPMs. You have 2 things going against you right now if you have the old V6 outdrive still installed - first is the gear ratio of the drive is probably 1.84:1 (common V6 ratio) instead of 1.98:1 (common for 3.0L) - this means your prop shaft is turning faster than it should. Plus, the prop itself is probably a higher pitch for the higher horsepower V6. Boils down to your engine doesn't have enough power to spin that big of a prop at that speed and needs a lower pitch to be running in the right power range.

 

[Bradmxz]

Ok that makes sense to me. I have the cover off the engine with me now and the serial number is 0c859704. The cover says timing should be 8 degrees btdc. But the idea of the prop being to big or to high of a pitch seems like a better idea to try to me. Not sure how to tell the prop size but there is a number on it that says J 15 x 17p. Maybe someone could lead me in the right direction here as to what I should have on there. If I need to change I could see if I can borrow one and try it out. But first I'll need to get it working better

 

[Bradmxz]

Serial number says 1990 when I use Mercury parts lookup

 

[Bradmxz]

Will a Mercury outboard prop fit my stern drive. A guy here has one for sale from a 200hp outboard. It's 14.25x 19. By doling a bit of searching that's the size usually associated with the 3.0l. I understand that my gearing is different but if this prop will fit it will get me much closer to where I need to be.

 

[flipbro]

It will fit but you're going the wrong way. Reread what Ricky posted to you.The 19 pitch will lower your rpms even more. Mabe a 15 pitch will help

 

[Bradmxz]

Ok I'm sorry. I assumed that was a lower pitch. So the way it works is the lower the number the lower the pitch? He is right I still have a whole lot of information to learn but that's what these forums are for and all your guys help is really appreciated. So you recommend going to a 15 pitch. Should I stay with the 15 diameter or also drop down in size there.

 

[flipbro]

15 is just a guess i'm not a prop guy so hopefully someone else can help you out. But yes the lower the number the less pitch..

 

[H20Rat]

Ok I'm sorry. I assumed that was a lower pitch. So the way it works is the lower the number the lower the pitch?

The pitch is the number of inches the prop should travel in one revolution. (at least in theory, it isn't perfect since there are different pitches on a single prop depending where you measure)

 

[Rick Stephens]

Since your current prop is a 17 inch, about the only thing you can try is a 15 inch. Not many are lower than 15, it is possible you will run out of prop choices before you get your RPMs in the right range. Diameter of the prop is a lot less important, as long as it clears everything.

I believe you should check your timing as well. That is both important from a performance standpoint as well as engine longevity standpoint. My suggestion is take a picture of your distributor and post it here. That will help us to know what proper timing setting it should have.

 

[Bradmxz]

I tried uploading a pic from my phone but it says the file is to big. I'll try again. If it doesn't work is there anyway around it

 

[Bradmxz]

Says file exceeds php size limit of 2.0mb