motor bogging down

[LindellProStaf]

I have talked about this before on here and need some more info. My 97 60hp merc starts great. Idles great. Trolls great. When I take off and accelerate it then bogs down. I have to slowly work it up to high throttle. I may have to do it a few times before it finally gets on plane. Then it runs great. When I slow down for awhile and accelerate I have to do it all over again. I took my carbs apart and sprayed them out with carb cleaner. I did not use the good stuff and soak them like someone mentioned I should do. Does this sound like a fuel thing or could it be coils or an electrical thing?

[delcecchi]

Spark advance?

[LindellProStaf]

Meaning what Del?

[delcecchi]

As the rps rise, the timing of the spark has to be advanced from say 5 degrees before top dead center to maybe 30 degrees before top dead center to properly ignite the charge in the cylinder. Too early and there is knocking. Too late and power is lost.

There is a mechanism or maybe two mechanisms that advance the spark properly to make it what the motor needs for a particular rpm and throttle position.

This is a two stroke, right? PM me with your email and information on which model, and I can send you the chapter from the service manual for the ignition system. (I bought the manual on CD on hsolist a couple years ago.) I learned about spark advance on a 62 comet and a 68 bug.

Or it could be something different.

[leech~~]

Does the motor bog-slow down or you just are not getting up on plan? If it sounds like the motor is reving normal or higher and you are not getting speed you may have spun the prop hub?

[LindellProStaf]

By bogging down I mean it just wont accelerate to get on plane. It starts to increase speed and then bogs out. I then have to keep feathering the throttle little by little and coax it up to speed. Sometimes it will go half way and bog out again and I start over. Eventually I get it up to WOT and then it runs great. When I slow down I have to do it all over again. I almost seems like I am coaxing a cylinder or two to kick in. It is a 3 cylinder 2 stroke. 1997 Merc. You can hear and feel it of course.

[RebelSS]

I'm going to go with a fuel delivery problem, as in a pinhole leak in the fuel line, bulb, or carb diaphragm. You're descring the classic symptons of this. Exactly what mine starting doing, pinhole in diaphragm was my prob. I suggest you start there.

[LindellProStaf]

Ok I will take the carbs off and check everything again. I will soak them in the parts cleaner for carbs overnight too. Thanks all.

[Kyhl]

When you say it bogs are you saying the motor bogs or the boat? It is tough to decipher because you use the reaction of the boat to describe what is happening. Based on the description it is a guess if it is a motor problem or a boat/prop problem.

When you say it bogs, does the engine rpm stop increasing or is the engine reving normally while the boat struggles to plane?

[leech~~]

If you can do a compression test as well. I had a 3 cyl Force with a froze ring that kind of acted like that.

[LindellProStaf]

Not a prop issue. The motor bogs down as in not hitting on all cylinders while accelerating. Then when I feather throttle I can eventually get it to take off and run smoother and increase speed.

[delcecchi]

If it was a car from the old days I would say accelerator pump. Do outboards have those?

For the youngsters here, in a carb, the flow of air past the jets sucks the fuel out. When you open the throttle at low rpms, the velocity of the air drops and the fuel isn't sucked in the right amount. The Accelerator pump shoots some gas in to make up for the loss of air velocity.

[Kyhl]

Based on that description I would say it is some sort of fuel issue, lack of or too much fuel on the act of throttle opening. Lack of could be air getting into the fuel line as mentioned.

[delmuts]

"For the youngsters here, in a carb, the flow of air past the jets sucks the fuel out. When you open the throttle at low rpms, the velocity of the air drops and the fuel isn't sucked in the right amount. The Accelerator pump shoots some gas in to make up for the loss of air velocity."

Kind of makes one feel OLD doesn't it Del!!!!

[delcecchi]

Yep. Lots of things do that now days. But most of my motor knowledge come from the days of carburetors, breaker points, vacuum advance, all that sort of stuff.

I've still got the 7/16 wrench that was shaped like a big C to fit the nut that held the distributor down. Used it on my VW and my barracuda.

[marine_man]

I'd start with a fuel pump rebuild kit... if it hasn't been touched it's coming up on 20 years, and I bet the diaphragms are about wore out...

Does it do this when you run it on the hose? You could try squeezing the primer bulb when this happens and see if it picks up (stops bogging). Have you noticed your primer bulb going flat at higher RPM's?

marine_man

[LindellProStaf]

When in neutral at the dock I can rev it up and it runs fine. It idles fine when I troll and always starts great too. Runs fine when I get it up on plane. Just hard to get it there. Just like it is not hitting on all cylinders when accelerating. I took apart and cleaned the carbs. (didn't soak them just sprayed them) I did rebuild the fuel pump at the same time too.

[boatfixer]

This does this every single time?

Have you tried pushing the key in (giving it a quick shot of gas)?

Have you gone through the carburetor synchronizing steps?

You can also try hooking up a timing light to each plug wire and watch the light to see if it goes out while advancing the throttle.

[EBass]

I've had similar behavior like that before. I could troll and start it fine, but would bog down when trying to get on plane. 1988 25H Merc and Shakopee Marine fixed it. I don't know if I can explain this correctly, but under the (I think it's called) Fly Wheel there was another part that had wires were worn down and exposed. I think was grounding when trying to get on plane. It took them a bit to figure it out. Something to consider. That's my

[CaptainMusky]

Is the primer bulb any good? If that bulb doesn't get hard and stay there then you might want to start with a new fuel hose with primer bulb.

[LindellProStaf]

new hose and bulb.

[LindellProStaf]

And new plugs too. Twice in case I got a bad one

[LindellProStaf]

Ebass, I am starting to think electrical.

[h8go4s]

I'm wondering if the bow-high attitude of the boat while trying to accelerate might be a clue. Something in the fuel tank may shift to where it cuts off the flow. Can you borrow a 6-galllon tank to try it out?

[raymondk]

had the same thing happen to me a few years back the first thing go get yourself a quality hose and bulb and get yourself some new oem connectors the connector on your motor looks the same I made the mistake by buying a aftermarket one which must of leaked some my bulb never really went soft it always ran good until I tried running it wide open I always had to feather it to get it up to speed .