Fouling on take off means its running too rich most likely or excessive Idling will load up a sparkplug along with being too rich. Lean it out and I bet it would be fine and gain a lil HP along the way.

If its a 2stroke motor, Id bet the MIX was off. This will most definently cause those issues. Could be something that simple.

I just thought about something else, first thing I would do is check the air filter, I bet its clogged or really dirty. I would pull plugs and put fresh ones in there, yank the filter and start it up, see what happens. The other thing would be the CHOKE. If its stuck or "on" too long, this could effect how it runs, some chokes control air, some control fuel.

Not necessarily. Some carbs use Needles to control air, while some use it to control FUEL and some use jets the same way, depends on what type of carb is on there. . if you go smaller on AIR, your going richer, if your going smaller on FUEL, your going leaner, personally, Id go the opposite, If its a fuel jets, Id figure out how to get more air, More Air + More Fuel = more power.

youd have to get a manual or check online to see how to LEAN that carb out. I would first clean it up real good. If it has air jet, it could just be clogged up some, giving you a rich condition, especially at idle and take off but once you get going, there is enuff air to keep it from fouling out while on the move. Just a guess without hands on.

Outboards do not have air filters. I do agree however that you may have some plugged air bleed jets. Do not change the main jets until you clean the carbs and VERIFIED the correct main jet and air bleed jet numbers. Make sure the float levels are set correctly also. After removing the carbs, you will have to re-synchronize the carbs and timing.

The OMC's use what is called a "power pack" for the ignition. They are known for failing but usually they will become intermittant first. The spark should jump a 1/4 inch gap. Clean the carbs first and see what happens. I don't have a manual in front of me so I have to ask, does this motor use choke "flaps" in the front of the carbs, or does it use a "primer solenoid"?
The reason I ask is the choke flaps may be sticking closed, or the primer solenoid could be hanging open causing a rich condition until the motor warms up and the flaps/solenoid works properly.
I'll be back at work tomorrow and have access to the manual. Is this motor original to the boat? Do you have the model and serial number handy so I can get hold of the right manual?
KB

Good call on the weak spark. Ya gotta have Fuel, Air & Fire.

I think youll get it. check carb first like you intend to and then go from there.

Keep us updated

check craigslist for comparable pricing, but that seems a bit high, but im not into boats.

Thats a fair price if you are sure the hull is in good shape. Check the transom for softness. Look for cracks at the bottom of the stern brackets (mounting brackets) and if it is depressed into the transom. Out here the trailer would be worth $500 at least.

Before buying, do the following checks.
Compression –– minimum 100psi and I like to see 120psi or so. Cylinders must be within 15% of each other pressure wise.
Check gearcase for water in the oil –– Loosen the bottom drain screw in the lower unit and see if any water or milky oil comes out.
Spark –– must jump a 1/4 inch gap.
General visual check –– look for frayed wiring, excessive oil/fuel leaks and hose condition (cracked or brittle).

Take it for a lake test too. Just because it runs in the driveway on a hose doesn't mean it will perform on the water.
Expect to install a new water pump impeller, lower unit lube, spark plugs and clean the carbs. The motor must be "sync-and linked" (synchronizing the carbs and timing) after the carbs have been removed and re-installed.
Good luck
KB

Bought the boat on Saturday.

Went through it even more thuroughly than i did when i was buying the thing. Making sure everything was there and i knew where everything was. Adjusted the controls, the throttle was way to stiff.

Headed out for the lake Sunday morning with a buddy of mine. Ran fine on the muffs, but we all know thats a lot different than running in the water.

Get it in the lake, high throttle lever up, press for choke, turn key, and much to my joy, she fired off and ran like a top. Gotta love the smell of two stroke in the morning.

Now for the (sorta) bad part. We take off after letting it warm up for a couple minutes and this thing refuses to get on plane. Its going about half speed(of what i know it can go).

We tool across the lake at half speed, catch a 9" golden shiner, and it starts to rain. We take off for the other side of the lake because its not raining over there. Well, its is raining there once we get there so i decide to just run the engine around to try to get some of the old gas out of the tank. I had put a high ratio of Sea-Foam in it before leaving.

After about 1.5 laps, it must have cleaned out the main jet(s) because this thing took off out of no where, planed out, and hauled ass. Went from not even registering on the speedo to 30mph(not fast i know, but its only a 70hp)

I think after going through the carbs and doing some checks on the ignition system this engine is going to be in tip top shape.

Boat was great all day, except the trolling battery needs to be replaced. Its 6 years old and was dead after only about an hour of trolling at speed 1 of 5 with random short bursts of 5.

Good deal, glad its working out for you

Will do.

What would have caused it to seal up and run great the rest of the day though? Just the vibration of the motor?


Rain was bloody cold. At that point it was 51ºF out there and the rain was colder than that. We had rain poncho's on, but doing 30mph across a lake soaking wet...is a chilling experience.

Solid, thanks for the idea!

The choke plates should return to the 100% open state when the solenoid releases. Can you see what it is hanging up on?
Maybe install a small return spring on the choke plate linkage if you can't find anything binding the linkage. There should also be a manual choke lever on the airbox. Check its function too.
The carbs and ignition timing need to be synchronized too. This may explain the stalling on acceleration.
Do you have a manual for the motor? Give me the model and serial number and I can send you some service info, like carb/timing synchronization instructions.
KB