Fish-Hawk.Net

Markus wrote:

I'm getting a hesitation at high RPM's and loss of power. We put new plugs in her, no change. Then I hooked my portable gas tank to it and no change. hmmmm. So it's not the plugs, it's not water in the gas, it's not an intake blockage in the gas tank. It sounds like fuel starvation, but I can't figure it out.

Didn't want this to die in your birthday string thinking someone may have some possible options for ya.

Question about how you hooked up your gas. Did you move the gas line over to each fuel tank, or did they each have their own fuel line.
I'm tacking a stab in the dark that maybe your primer bulb is bad. Was the fuel line solid in both cases?

Did you run that 'engine tuner' stuff yet?

M.T. Livewell

MT. Ya I ran some conditioner through it.

As for the gas line, I disconected my main line at the motor and directly attached the portable gas tak. It has it's own gas line and bulb. So it's definately not in the gas line, bulb or tank.

What about the filters? They may just be a little clogged up.

No real idea but that was a problem I had on my car but don't know if outboards have some type of screen or filter for the gas to run through.

YA, I had a guy check the filters and he said they're great. He ran the motor for 4 hours and said it runs like a top.

The problem only happens at high RPM's when the motor is under load fromthe boat....which he can't simulate in the shop.

I'm gonna have Turkeyman look at the filters again in Quinte.

What about the oil injection system? Does anyone know anything about this? What if at higher speeds..fuel consumption is great and the oil isn't being injected into the line at the right volumes?? Is this possible? Would it cause hesitation or poor combustion?

Do you find it is smoking at higher RPMs, maybe getting too much oil?
You trollers are so mean to your outboards.

MT

I'm with you there MT...

Me thinks he's trying to get out of the rematch from Muskrat...

In all honesty, the motor is probably just getting old, like it's owner... Lord only knows how many hours you put on it this year alone.

TM, will just convince you to "let the buying continue"

hmmmm. Good suggestion MT. The wind was pretty brisk last night and I never noticed any extra smoke. But there is a little build up of oil residue under the motor from the exaust....you might be on to something here. It would definatley have trouble combusting a heavy oil mix..and that would cause the hesitation.

Is there a regulator for this....or is it computorized?

Hey Markus,

I have the same thing happening on my old boat / Evinrude motor. I just adjusted the carbs to see if that has anything to do with it, although I was told by a local Marine here in Ottawa that it is most likely the electronics. Check all you connections and make sure they are tight. You might need to change your electronics box. What kind of motor and what year is it?

Gordo

Markus this sounds like a problem I used to have where I didn`t know it but about half of my float reservoirs in my carbs were straight water. The gas would sit right on top of the gas and at low speeds the gas was being replaced fast enough to run the engine fine. It was only when the engine started sucking in some of the water that the problem started. I had to dismantle the carbs eventually but ..... I did run for a lot longer using water displacement stuff in the gas.

The problem developed over years of condensation buildup. Just a thought.

I have doubts that the oil injection is computerized on our units. I would expect it is more likely just regulated by pressure valves and vacuum.

Too much oil would be obvious on your spark plugs. When you pulled them, were they black?

Gordo, I don't think anything is really controlled by electronics on this motor. Rather, the electronics are sensors to indicate when there is a problem (as usually too late). I'm sort of with Steve on this one, she's been rode hard and put away wet. A carb rebuilt and a good compression test might shed some light on the condition of your engine.

MT

Gordo, it's a Nov 1999 Johnson.

How do you chagre an electronics box?? Or for that matter...check the current charge in it?

I think he meant change, not charge.

The only good news so far, is that in all likelyhood, no one will be able to open her up to WOT (Wide Open Throttle) this weekend.

MT

Markus wrote: What about the oil injection system? Does anyone know anything about this? What if at higher speeds..fuel consumption is great and the oil isn't being injected into the line at the right volumes?? Is this possible? Would it cause hesitation or poor combustion?

Im not a mechanic or anything, but I did spend more than enough time working on 2-stroke engines in snowmobiles, dirtbikes and some outboards.

The oil injection systems I have workd on (primarily Yamaha and Bombardier systems) are powered by suction and have a valve that controls flow based on position of the throttle. IE - the more open the throttle is the more oil can be sucked into the engine. Real specific eh ? Well, the real reason that I am deciding to post here is that I have run a lot of gas through my high performance 2-stroke engines, and having too much oil in the gas wont cause the kinds of problems you are seeing Markus. It may be hard on the plugs and cause the machine to smoke more, but the difference between a 50:1 fuel/oil mix and something very oil rich like 20:1 is pretty small ( 2% oil vs 5% ). I even know lots of people who run pre-mixed 50:1 fuel in machines with oil injection as well - especially for break in periods. Not enough oil from the injection system is going to be pretty undetectable until the machine just keels over and dies - requiring an expensive trip to the shop to polish out the scoring and replace pistons. Not a pretty sight - been there, done that (broke the throttle cable linkage that opens and closes the oil injection valve on my snowmobile - so the engine was only getting the oil metered for idle RPM regardless of real throttle position).

To me it sure sounds like some kind of issue with the ignition system - the digital ignition systems on modern outboards are very complex - its a whole little computer in there. Its a real pain to diagnose since they only happen under certain conditions. The ignition timing curves are controlled by the digitial ignition computer based on RPM / throttle position / exhaust temp and other sensors. Unfortunately the digital ignition systems arent as simple as the older fixed ignition timing units, but they are how we get better power and efficiency from smaller motors. To me, it really sounds like you have a electronic / timing issue - maybe a faluty sensor of some kind ?.

Hope that you can find out what it is and that in the mean time the motor is servicable enough for the rest of the season.

Fox

Found this discussion string on another site with Johnson engines doing the same thing.

http://www.iboats.com/cgi-bin/ubb/ultim ... 8;t=027153

I-boats.com very interesting site.

http://www.iboats.com/cgi-bin/ubb/ultim ... 8;t=027115

Thanks Firefox! My mechanic, just told methe very same thing! He is leaning towards ignition problems in on of the cilinders.