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20 hp Evinrude 1989 problems.....

I

iceknight66

Contributing Member
Hi all, I currently have a 20hp 89mod Evinrude. Now the problems Is, I cant get above about 2000 under load, On the muffs Is fine, While In the water the motor Idles perfect, runs fine in gear, But once Its opened up it struggles and goes nowhere. Since this problem started, Ive checked compression. Had the carb done. Replaced the Stator/trigger assy. Now the bottom plug seems to be getting an oily substance on it. Spark jumps a half Inch.


Could It be a lower seal? Or something else? I dont think Its a coil related problem...


Anything else to look at? ALso the temp switch has a wire that runs Up to the stator trigger assy? Could It be that temp switch in the front of the head? whats the wire do?


Thanks.
 
Re: 20hp Evinrude 89 problems.....

Check the fuel pump diaphragm for a hole / rupture.------Put a timing light on it and verify that you have good spark as you speed up.-------------Both cylinders should give a steady bright flashing light.--------No point replacing parts and guessing , just costs too much money.
 
Re: 20hp Evinrude 89 problems.....

replaced the fuel pump, new primer bulb, fuel lines, fuel line connections, New fuel tank also. Checked with the timing light and the spark is good, spark also jumps plenty. As soon as the Primer on the engine is touched the motor dies, so its getting plenty of fuel,

Could It be the lower crank seal making the engine lose all this power?


Cheers.
 
Re: 20hp Evinrude 89 problems.....

Check exhaust housing seal. have a nephew with a johnson 112 that did samething and it was exhaust seal letting exhaust up to carbs.
 
Re: 20hp Evinrude 89 problems.....

If it was the lower crank seal there would be huge loss of crankcase compression !!! -------this would mean very poor idle, but you say it idles like a top.
 
Engine NOT running but in forward gear........ check to see that the throttle butterfly is opening full (Horizontal position) and that the timer base under the flywheel is at the full spark advance position.

NOTE: Do not ever open the throttle when in neutral or on a flushette. That runs the risk of encountering a runaway engine whereas the rpms will continue to increase even with the throttle closed. By the time you figure out some way to stop the engine, connecting rods will be flying out the side of the crankcase.
 
Ive checked the butterfly, opens up almost horizontal. the timer base under the flywheel is also perfect..... It totally buggers me..... .
 
Compression should be approximately 100+ psi and even on all cylinders. Is it?

With spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?

Spark plugs should be Champion QL77JC4 plugs, gapped at either .030 or .040 . Try both gaps as some models show improved performance with one or the other.
 
Running NGK plugs currently. 130psi on cyc, spark jumps an easy 7/16th of a gap with the Snap- replaced all the electronics anyway. Could it be the plugs all of a sudden?

Thanks for everyones Input.


Cheers.
 
3rd dealership today. 7 workshop hours and still no fault found. Although the water is being turned absolutely black, they have pulled the powerhead off to check the bottom seal.. Tried all new electronics agian today. another carby. checked timing, advance, throttle position. No fault found. Sometimes the engine was getting full throttle. then it would die back down agian, Seems to be more like a spark issue but everythings been changed twice. When the top plug lead is pulled off the engine dosnt change much, when the bottom lead is pulled off the engine almost stops. BUT the bottom spark plug is really black yet the top is burning clean....

Strange things....
 
Have you swapped the coil to see if the problem follows the swap? Some electrical parts fail when hot or stressed. Sounds as if you have covered most bases
 
reed valves were checked while the carby was off and seemed operational. coils were swaped and still the same problem persisted... Today Im putting 2 new coils on also to see if maybe by some miricle both are malfunctioning....

Thanks for the input guys!
 
ok so today the reeds were pulled off, the coils checked with new coils, fuel pump was pulled off agian, and YET were still at the same problem, Plugs seem to be awfully wet today and the motor SMOKES as if its on fire. Tried new fuel and oil also. Heaps of spark, Timing is spot on. plugs are right. Trying another new fuel pump in a few days when it comes.

What else is there????....


Thanks.
 
I should say also That sometimes the motor jumps up to full throttle, but very slowly. then its fine usally untill you back the throttle off.... - also today another carb was tried off another motor and still ran the same....
 
You've made a new statement of " sometimes the motor jumps up to full throttle, but very slowly."

That (very slowly) indicates either a fuel problem (unlikely) or a sticking timer base under the flywheel. Check to see if there is anything interfering intermitently with having the timer base advancing to its full spark advance position (up against the rubber bumper).
 
had the flywheel off twice, and made sure there was no foregin material. advances all the way untill its at the bumper, while its down low and struggling you can use the timing light and see the motor is at 32deg, Im thinking maybe it was a dodgy fuel pump, and the new one was also dodgy... I hope so anyway... Otherwise Im throwing the thing out and getting a new motor :)
 
I had a 35 hp Johnson (about the same age as yours) a couple of years ago that was doing the same thing. Ran great and revved great until you put a load on it. It would run good and steady at say 5 mph, but any more throttle and it would bog down.

In my case it was the ignition switch. I know it sounds odd, but the repair shop put in the new ignition switch and it has run properly since.

Good luck.
 
The ignition switch thing..... it can fail in two ways.

1 - A intermitent short between the two "M" terminals can result in erratic spark.

2 - A very low voltage short between the "A" terminal and the "M" terminal that the black/yellow wire is attached to will affect the powerpack in weird ways, and eventually destroy the powerpack.

To eliminate (test) either of those problems, simply disconnect the black/yellow wire at the ignition switch. If this causes the problem to cease, replace the ignition switch.
 
Another interesting read. There are two small hoses, one goes between upper and lower crankshaft mains and the other, between the inlet manifold and the top induction plate. These have to be correct connection and serviceable. These have been checked?
 
Have checked the valves and hose from the top to bottom, I think the Inlet manifold one would have been checked. what do you call the Induction plate?


cheers.
 
Sorry, bypass cover. I tend to mix up different terminology somewhat. Should be a hose bottom of inlet manifold, under carby, that goes to a nipple on the top of the removeable induction plate Bypass Cover) on the starboard side of the powerhead.
 
No worries. I rememberd checking the one hose, but not the other one you mentioned, I was getting excited that maybe one had been missed and it would be the proplem, Nevermind, Thats for the help anyway :)
 
Where are these dealerships located ???---------Has the primer unit been eliminated as a possible problem ( too much fuel ) ------Has the lower unit been checked ( binding )------------------These motors are not that complicated.
 
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