Evinrude 1984 70 HP stalls under Heavy load

[kynolan2183]

I have an 1984 70 HP evinrude that stalls under very heavy load. IE throttling up while putting it on the trailer.
Boat runs fine and has the top end is 35 mph on a 17 pitch. This is a 17 foot Ozark bass boat
I have checked the spark. Rebuilt and cleaned the carbs. Checked the timing. The pump bulb is fine. Even tried hitting the choke primer to send it some extra fuel. No luck. Floats on the carbs are set correctly.

Questions:
1st The top carb spits a little fuel at idle is this the symtoms of a bad reed or normal?

2nd Any ideas on the stalling thing under heavy load?

3rd Anyone put boysen reeds on this model motor before?

Thanks for your help

 

[OBJ]

Re: Evinrude 1984 70 HP stalls under Heavy load

If the top carb is actually spitting fuel OUT, then that's a good indication of reed damage. If the carb is just "sneezing" or "coughing", the idle air jet may be plugged up some.

Got the reeds in both my engines, one a two cylinder and the other a four cylinder. Wouldn't be without them.

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

The spitting of the fuel out of the top carb is very misty and you can barely see the drops. You can count the number of drops in five seconds. I have debated on the reeds bacause the compression is good at 135psi 135psi and 125psi.
At about 1300 rpm the droplets stop.

Any ideas of the Stalling while putting it on the trailer?

Thanks
Kyle

 

[ezeke]

Re: Evinrude 1984 70 HP stalls under Heavy load

If, when loading the boat, the angle of the engine exceeds 15º, you may be dropping the floats enough to flood the engine out.

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

I have thought of that "angle of the engine" and have ajusted the trim accordingly.

and I have a manual on this motor and it doesn't help with this problem.

This is really screwy and it is driving me ger-nucking futs

Thanks for everyone's help
Kyle

 

[emdsapmgr]

Re: Evinrude 1984 70 HP stalls under Heavy load

My 92 spits a little gas out of that same carb. Also thought it was a reed, so took the whole front end off the engine-only to find the reeds were fine. Then noticed a slot in the face flange of the carb where it bolts to the engine. Also a cast passage for fuel- cast into the intake that aligns with the slot on the mounting face of the carb. When on the compression stroke, it puffs a little fuel back through that passage, through the flange slot and eventually out the front of the carb. While I would say this is not "normal" for any two stroke, it must be "normal" for this engine, as the engineers designed it that way. As you say, it is a mist. The engine is stock and had never been apart.

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

Thanks emdsapmgr you may have just saved me from ripping it apart. Do you have any issues with your motor stalling on wide open throttle under heavy load. Like putting it on the trailer. I have no other problems at this point other than that. She revs up fine, shoots out of the hole great, starts well on a cold day for a two stroke, but i can't place her against a wall and just rev her up. I could do that with my 30 hp evinrude but not with this one and I could to it with my 3.0 liter ski boat. I am bothered by this.

thanks again

Kyle

 

[OBJ]

Re: Evinrude 1984 70 HP stalls under Heavy load

Hey Kyle, how low in the water does the engine set or looking at the anti-cav plate (the plate right over the prop), where does it set in reference to the keel of the boat?

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

The cavitation plate sits even with the keel. And the boat sits high for a bass boat in the water since it is rated for a 90hp. The Motor has is a through prop with the by passes up top. I am going to go check them for a mud dobber nest when I get done writing this.

Note: On the air box there is a cork gasket between the carbs and the box. Also from the bowl there is a vent that leads up and into the box.

I found that the cork gasket could have been some what blocking this vent on the carbs as the gasket is old.

I replaced the gasket with a very thin layer if silicon and avoided the quarter inch vent. Put silicon on the threads of the bolts holding it in place to stop any vibration loosening. I will replace the gasket when I can get one off the net.

Question:
Could a restricked vent to the bowl cause the problem of Stalling while under heavy load but allow the boat to act fine on the water?

Thanks
Kyle

 

[OBJ]

Re: Evinrude 1984 70 HP stalls under Heavy load

I would think that a restricted bowl vent would be felt through the entire throttle zone. It would restrict the bowl filling as fuel is used. Gotta' let the air out of the bowl as fuel is added. Be real careful of using silicon. It don't take well where there is fuel and will become like jello. If it squeezes from the gasket surface inside the carb cover, there is a risk of some of the mush getting into the carbs.

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

I will get some gasket maker from the auto parts this week and replace the silicon.

Buy the way the upper exhaust vents are good and clear.

What else could be causing the stalling?

Thanks
Kyle

 

[emdsapmgr]

Re: Evinrude 1984 70 HP stalls under Heavy load

Have not had any problems with my 60 operating at high rpm or under heavy load. Still leaning to a fuel problem. Possible you may be running out of fuel under high load. Priming (choking) at that point is a good diagnostic procedure, but it won't help if the pump is not delivering enough fuel. Possible that your carbs are consuming more fuel than the pump can deliver..Not sure if you said you tried priming the hose bulb when the engine was cutting out or not. If you did not do that, have a friend squeeze the bulb when it starts to cutout and see if it improves. You have the simple fuel pump on yours and they do make a rebuild kit for the pump (only about $15. P/N 393103.) If you have a built in tank, take the check valve apart and see if there is any debris limiting the ball travel or restricting it.

 

[mikesea]

Re: Evinrude 1984 70 HP stalls under Heavy load

is the timer base under the flywheel operating in sync.with the throttle,you might not be getting advance

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

The primer bulb stays hard and I have tried the electric choke trick no luck on that.


I am going to check and make sure the timing is advancing correctly by the book again. Will only take a few minutes.
I am working on the boat and checking this forum during cig breaks. Don't like to smoke and play with gas.


Thanks for everyone helping.

Kyle

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

OK I think that I may have found the problem but I won't know until I can put it on the lake.

There is a connecting rod from the timing advance lever to the armature under the fly wheel which is connected via ball and socket on both ends.
One of the ball and sockets is very loose Like 2 to 3 mm of play. This can't be good.
I know that an engine can tolerate 1 to 2 degrees of timing being off. Lets face it our eyes just ain't that good. But lets say it is off by 2 degrees with the play in the shaft. Under normal load that just might be fine and you would never feel the difference in the engine. How ever on extreme heavy load, like putting it on the trailer, pulling out a sumo wrestler on skies ect that small of a timing difference might cause it to stall. With the 2 to 3 mm play with pushing the armture forward would retard the spark to much. All spark is retarded some what 3 degrees to 5 degrees depending in the engine. But say this caused the spark to be retarded 7 degrees, I would think that under light load I would never see this problem but under heavy load the engine might stall.

I will need to get a new ball and socket for it, which might be a pain. So for now I have used some JB WELD on the socket to rebuild it. I will let everyone know how it turns out. I hate plastic in engines!!!!!!

Please let me know I my thinking on this is correct
So here's the question
Is my thinking on this correct?

Thanks for everyone's help
Kyle

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

On the above I ment to say all spark is Advanced some what and that there would not be enough advancement if there was play in the shaft.

Sorry for the mistake but technical writing was not my strong suit in school

Kyle

 

[mikesea]

Re: Evinrude 1984 70 HP stalls under Heavy load

you should have no problem getting the part,still a commonly used item

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

Got the part on order. It will be in before thursday.

Kyle

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

Ok,
The part came in and is installed.
Amazing how much better it idles now.
When I did the link and sync with the new part I found that the connecting rod to the throttles was short by 2 turns out.
Onve the link and sync was correct and evrything looked good I started her up.
Remember the spitting carb issue, well it no longer spits.

Now I will need a water test. I will get that on Friday.

 

[kynolan2183]

Re: Evinrude 1984 70 HP stalls under Heavy load

Water test update.

The linkage was the problem.


Thanks to everyone
Kyle