96' Merc 40 2 Stroke Bogging out???

[medo1]

Hi there, hope someone here can help.

We have a 1996 Mercury 40 HP, 3 cylinder 2 stroke, on a 16 foot hull. We went out a couple of weekends ago and it ran great! Now the last 2 times we have gone out, it starts to bog out on acceleration. It idles no problem, and revs up in N no problem, but bogs out under load.

What could be the problem?

I've checked the fuel filter, it's clean. I've checked to see if any air bubbles in oil injection line, there are not. Sparkplugs seem to be clean, not fowled.

Big HMMM here. Is rather frustrating.

Thanks,

 

[Silvertip]

Re: 96' Merc 40 2 Stroke Bogging out???

When the engine bogs, squeeze the primer bulb. If it takes off, you have a fuel pump problem.

 

[medo1]

Re: 96' Merc 40 2 Stroke Bogging out???

Thanks. I'll try that next time I get it in the water.

 

[medo1]

Re: 96' Merc 40 2 Stroke Bogging out???

When the engine bogs, squeeze the primer bulb. If it takes off, you have a fuel pump problem.

Well, I tried this, squeezing the bulb, did not make any difference.

Mind you, there are five of us in the boat. There is myself, my wife and three kids, kids are 4, 10, and 11. Both my wife and I are in great shape and not overweight. Could it be that we ALL are putting too much strain on it? I for some reason want to so no. Like I said in the original post, "it ran great a few weeks ago", know this.

But, when everyone gets out of boat, it does run somewhat better, nothing like it did though.

Puzzling.

Could it be a bottom-end problem? It doesn't click or grind into gear.


Thanks

 

[medo1]

Re: 96' Merc 40 2 Stroke Bogging out???

Mind you, there are five of us in the boat. There is myself, my wife and three kids, kids are 4, 10, and 11.

When everyone gets out of the boat and I'm the only one left, it runs a lot better. BUT, still wants to bog out. I can throttle right up then have to back throttle down a little to ease the sputter. Could this be a fuel/electrical problem?

We bought the boat from family friends, who let it sit for three years. We've gone through everything but the motor on this boat.

 

[medo1]

Re: 96' Merc 40 2 Stroke Bogging out???

Could the octane of fuel be the problem?

We've been using 85. I'll try something higher.

Can octane make that much difference?

Is higher than 87 better?

 

[medo1]

Re: 96' Merc 40 2 Stroke Bogging out???

Well, I just got back from a close local res. I tried using 88 octane. It ran considerably better than before. I was able to put the hammer down and go. Pulled the 11 yr old boy around on the tube for a while, then it started bogging out again. We dropped anchor and swam for a while then started it back up. This time, I slowly throttled up, sputtered a bit, then ran well.

The thing is it still wont let me drop the hammer and go. It used to. Could this be a carberation problem?

 

[scrobo]

Re: 96' Merc 40 2 Stroke Bogging out???

Did you open the fuel vent on the cap?

I only ask because I was boggin out this weekend and got really frustrated untill I noticed the vent was not opened

 

[medo1]

Re: 96' Merc 40 2 Stroke Bogging out???

Did you open the fuel vent on the cap?

I only ask because I was boggin out this weekend and got really frustrated untill I noticed the vent was not opened

Yes. The vent is open on the cap.

Thinkning about pulling the carbs off this weekend and cleaning them. This motor did sit for 2 1/2 years. Hoping that this does the trick.

 

[jvjmw1]

Re: 96' Merc 40 2 Stroke Bogging out???

I am experiencing the same problem with my 1995 90hp jet sport. It runs fine for a while, then falls on its face. I bypassed the fueltank and lines figuring there maybe something impeding the fuel. This did not help. The fuelpump has beed rebuilt. I wish I had the answer for you. If you find the answer, I would greatly appreciate it if you would pass it along. Good luck!

 

[RaScLeS]

Re: 96' Merc 40 2 Stroke Bogging out???

my old merc 700 bogs, its getting fixed right now, it was the stator/trigger assembly, at first I guessed the powerpack until i tried another one