evinrude 50hp 1987 carbs spitting back and misfiring

[phillnjack2]

Hello
First of all i will explain what is happening, and then hopefully someone might be able to help or give some usefull advice.
A friend has a 1987 50hp evinrude, it used to be vro but its now on premix with everything to do with vro taken of and discarded.

This engine has sat for about 3 to 4 years, and now its time to come back out and play.
So we put some fresh fuel in and fired it up.
Firstly we noticed that its spitting back fuel through both carbs and is misfiring a bit.
Secondly it seems very very smokey, even after running for 30 minutes.
The throttle linkage to stator seems very floppy, the stator bit it attaches too seems to be getting hit on each revolution due to flopping up and down. Is the plate meant to move vertically ? i know it has to move backwards and forwards etc to adjust the timing when at full throttle etc, but this seems a bit strange to me.
The fuel thats getting spat back from the carbs is a bit much, its more like its a back fire from the crankcase,just without the loud bang.
We ran the engine on muffs for about 15 minutes and it does seem to be revving up freely and starts pretty good.
There is a lot of blue smoke, infact it seems to be a hell of a lot to be honest.

When we put it in a test tank to see if water circulation from its own pump was good ,we noticed the water turning black very quickly with a lot of oil on top of the water.
It turned into a black oil mess very quick (tank has now been cleaned back out ready for any more testing)

we know the fuel is fresh and its 50-1 mix, as we done this just 20 mins before starting the engine.

The compression reads 155 on top piston and 153 on bottom piston.
Spark is very good on both cylinders as well.
The engine does sound to me like its missing a bit, could any of the following be the cause

does this sound like
1 stator problem (loose stator plate)
2 problem with reeds (reeds sticking open )
3 cylinder head gasket (we ruled this out when saw compression)
4 other electrical problem
5 carb problem


any help would be good as we hope to get this rigged up on my 13ft dory to test engine out on the river very soon


phill

 

[phillnjack2]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

come on experts/advisors /people who know their stuff
i realy need to get some answer quick while the weather is dry here.
Once it starts to rain the uk we can get it for weeks and im only able to work outside on this old beast.

phill

 

[Will Bark]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

I'm no help on that particular engine but I do know that one of the first questions is going to be "what's the model number?" The gurus need that to give you help. Good Luck.

 

[phillnjack2]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

Ahhh good thinking WILL BARK

Engine model E50TLCUD and Serial Number G1421825

Like said above, it used to be VRO but thats all been taken off, and its back to being pre-mix engine at 50-1.

thanks will bark

phill

 

[rolmops]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

Certainly a carb problem but in addition I would check if the fuel enrichener is stuck on open or whether bugs have built a nest in the carburetor barrels.
In a nut shell,you have way too rich an air fuel mixture that causes the smoke, so you must either decrease the fuel or increase the air

 

[phillnjack2]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

I realy dont think its a carb problem for reasons below.
Floats are at correct level, carbs been fully stripped down and cleaned.
on these carbs there is no way of changing fuel settings.
there is no adjustment other than float level,no air /mix screw etc.

but ill have another look at the carbs and will check the enrichment device.
phill

 

[rolmops]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

Run it without the cowling and see if you still have the same problem.

 

[rolmops]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

sorry double post

 

[phillnjack2]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

We are running without cowling and without front air box.

We have noticed there is vertical movement in the stator plate connection, could this cause timing to be out ?
how do the stator plates connect / is there a bearing that they run on ? or is there a plastic slide type thing etc.
Ive looked in the repair book and cant see exactly what im looking for.
would like to know a little bit before tearing into the flywheel removal etc.
although ive worked on many outboards over 30 years, Ive never taken a flywheel off an outboard before,so
this is complete virgin territory for me.
the plate is sliding forwards and backs with throttle movement,but the looseness of the plate seems to be wrong to me.
Im pretty sure its hitting the flywheel when its running.

ive added a pic with red arrow pointing to the suspect part,to show whats moving up and down and i think
hitting the flywheel.



phill

 

[Mas]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

Sheared flywheel key?

Mas

 

[OptsyEagle]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

I should add that I know very little about your model of motor, but when I hear about carbs spitting back and misfiring I can't help but think that you may have a problem with your reeds. Let's face it, reed valves are there so that the fuel will flow the one way and not the other. Since it sounds like the fuel is also flowing in the other direction, it seems likely that one is stuck open. I have never personally experienced this problem, but I would imagine that it would cause mis-firing. Have you tried pulling one spark plug at a time to see if it will run on one cylinder (assuming you have 2 cylinders, but that I do not know). I would imagine a bad reed would make that cylinder weak and misfiring as opposed to dead. That last part is just my guess.

 

[phillnjack2]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

Ok i have had the reed bloke out and giving it a very good close look.
The reeds all look very good, no splits, no rough edges ,no cracks etc.
The complete reed pack looks like brand new..

As for a dead plug, no !!
both plugs firing and sparking very well,
if i pull one plug the engine will drop revs and exactly the same with other plug.
No wires shorting out as far as i can see.

One thing i have noticed is that when the throttle lever is put forward it automatically moves the timing straight away, then once it gets to the end of timing travel the throttle level continues on to full throttle.

I was thinking that the timing lever shouldnt move untill about half throttle then the timing moves ...
but i could be wrong of course.

cleaned and checked carbs again while it was stripped down.



phill

 

[phillnjack2]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

I have taken the fuel enrichment device of and had a look at it.
everything inside seems clean enough but when attaching power to the device nothing seems to happen.
Now when i blow down the pipe from the fuel pump to this device i get good clean flow to both outlets !!!!
shouldnt thids be closed off untill power is introduced to the unit , or untill its manualy opened ?????

i cant seem to be able to shut this off, and presume im getting chocked up all the time by this device.

someobody please help on this matter


phill

 

[rolmops]

Re: evinrude 50hp 1987 carbs spitting back and misfiring

There may be a few things wrong here. The primer is activated by pushing the ignition key while in the on position and starting.Sometimes the key stays stuck in pushed down position, leaving the solenoid in open position. If you want to test the solenoid windings,set your Ohm meter on low and test between the purple/white and the black leads.It should read 5.5 plus/minus 1.5 Ohm.
There is also a little (red?)lever on the tip that enables you to manually open and close the primer.Maybe it was left open? If my memory serves me well it is open when it is horizontal and sticking out. It should be turned up and closed.
A very simple way to check, is by sticking a clip or plyers on the fuel supply hose to the primer thereby effectively closing its fuel supply. If things get better,you found your problem.Heck your rpm should go way up,so be careful doing this if you run the engine on the muffs.
You can also just take the thing apart and clean and inspect it,it may be full of varnish and crud. Just be careful because it does have a spring inside.Make sure to put the check valve in in the right direction.
It would be a very good idea to buy an OMC factory original service manual.They are great to work with.
Good luck,Cornelis

PS. The more I read this post the more I get the feeling that this engine was taken apart and rebuilt completely,but the putting back together was done in a less than thorough way and you are reaping the fruits of that now. I would go over every last bolt and nut and put nevercease and locktite (blue) where it is needed. That includes the stator plate,where either a ring is missing or the screws were never tightened or maybe they vibrated loose.The link and sinc should be looked at as well.
All these things are easily fixed, specially with a manufacturer's manual in hand.