Only Running on One Cylinder

[isuckatboats]

Hi everybody!

I'm new to this site, but I think you guys can help! I work on cars and lawn mowers but very new to boats and TBH, two strokes usually kick my ass.

My dad and I bought a 15' boat with a 1974 Evinrude 50 HP outboard on it. The motor is a two stroke (my luck) and had been sitting in the guys yard for at least three years. I have done a multitude of repairs on it after looking at forums but I cant find threads that point me in the right direction anymore.

Repairs as follows:

- New Starter.
- Re-wired ignition rotatory switch.
- New starter wiring.
- New starter solenoid.
- Lubricated all control cables.
- Repaired Hull in multiple spots.
- New trailer light wiring.

The thing kept overheating. So....
- New impeller and all associated parts (seals, wear plates, ECT).
- Removed thermostat, and put two part epoxy in water jacket to force water around the cylinders and into block.

Then it wouldn't idle...
- New fuel pump.
- Rebuilt both carburetors.
- Inspected the reed valve and saw light coming through openings, so I bent them back into place as a test, it didn't help.
- Replaced all seals when putting back together, or used high temp RTV when practical.
- Adjusted the carburetor throttle linkages (The one that ties both carburetors together).

I found out its not running on the top cylinder.
- Compression tested both cylinders, read 120PSI on both.
- Spark is good on both cylinders, jumped a 1/2" gap.
- Fresh fuel, double checked the oil ratio at 40/1.

The motor wont run at all on the idle circuit, and seems like its running lean at 1/4 throttle but the carbs on this motor don't have a high adjustment screw. So here's where I dug my own grave. To make up for it I attempted to adjust the timing linkages by ear to no avail, and out of frustration I ended up messing with just about every linkage on the motor and nothing seemed to help it run at all, and now I try to run the engine at throttle and it wont do that unless you physically have your hand on the throttle linkage actively reacting to when it starts to die or rev too high.

I've lost about 15 weekends to this thing and I'm sick of it, any help would be appreciated.

 

[racerone]

Linkages do not go out of adjustment on these. !!----Sounds like you just need to revisit your carburetor work.----Perhaps a high speed jet ( orifice plug ) is plugged !

 

[isuckatboats]

Thanks for the speedy reply racerone!

That was actually my next weekend plan to drive back into the carbs
I also just bought an induction timing light so I can reset the timing back to factory specs (I believe its 7 degrees ATDC at idle and 19 degrees BTDC at WOT). I'm also hoping to find something to help me set the rest of the linkages back to factory specs before trying to tune the engine again, but I'm still baffled about the top piston not firing. It wont idle because the cylinder wont fire and I cant tune the motor unless both cylinders are running...

 

[oldboat1]

Do a simple continuity test on the coil/spark wire. Check the connecter in the plug boot to make sure it is contacting the wire. (btw, should run with a 50:1 mix.)

 

[isuckatboats]

Do a simple continuity test on the coil/spark wire. Check the connecter in the plug boot to make sure it is contacting the wire. (btw, should run with a 50:1 mix.)

Ok can do, and thanks for the information!

 

[isuckatboats]

Ok can do, and thanks for the information!

Alright, the plug wire is making contact with the spark plug and I rang out the ignition coil. Primary winding has a resistance of 0.9ohms, and the plug to the CYL-1 wire has 2Kohms, not sure what it should have. Excuse my ignorance but I'm curious if the spark can jump a 1/2" gap shouldn't it be strong enough to fire the cylinder?

 

[Crosbyman]

ok not firing... but do plugs seem wet with unburnt fuel ??

if not..... fuel is not reaching the cyl. you need to find out why .

stuck reeds ?? dirty/plugged carb ??

 

[isuckatboats]

The plug was in fact wet every time I pulled it I had to wipe it clean. I also swapped the plugs to see if the problem followed, however, the top cylinder was still not firing. I'm also having trouble seeing why this would be a fuel delivery issue, I mean it seems lean but I cant even get the top to fire with ether (I know its bad for two strokes). Also after the reed valves the block is one piece so it should allow the #2 carb to feed the #1 cylinder and vise versa.

Lol I've never seen anything like this, but I know these motors can require very precise ratio's, I'm just not sure what else to test? All I think I can do is put everything back to factory spec's, clean the carbs again and cross my fingers.

 

[racerone]

Sorry-----But the top carburetor only feeds the top cylinder !!-----Your motor is in fact 2 separate engines ( crankcases ) and there is a need to understand the concept !

 

[isuckatboats]

wel

Sorry-----But the top carburetor only feeds the top cylinder !!-----Your motor is in fact 2 separate engines ( crankcases ) and there is a need to understand the concept !

Well that's why I'm here This issue seems like it is out of my league.
Admittingly I don't understand the one off concepts about boat motors that don't already apply to basic two stroke operation (like chainsaws and weedwhackers).

However, you have just given me an idea! So if this is basically two separate motors, and one isn't running but has gas, air, spark, and compression, could the top "motor" just be flooded??? In my experience with other two stroke motors I've seen them flood in the first pull and just not start until all the fuel evaporates. This would also explain why ether didn't help! If this is true, likely, or even possible with these engines what could be the culprit?? Bad needle or seat on the float?

 

[juno pierrat]

Just a quick check, top cylinder runs the fuel pump, you list it as new, but check this, remove pump from block, hoses still attached, pump the primer bulb, does fuel come out the bac of the pump?

 

[oldboat1]

Alright, the plug wire is making contact with the spark plug and I rang out the ignition coil. Primary winding has a resistance of 0.9ohms, and the plug to the CYL-1 wire has 2Kohms, not sure what it should have. Excuse my ignorance but I'm curious if the spark can jump a 1/2" gap shouldn't it be strong enough to fire the cylinder?

Videos — The Penn's Old Outboards

www.oldoutboard.com

I think the ohm reading for the for the secondary side (plug wire side) is a bit weak. Recalling from the Penn instructions, you should see 4 to 6 in a good coil with the tester set at 1K ohms. (Check the link. Hopefully, the reformulation still contains the instructions for measuring coils.)

 

[isuckatboats]

Just a quick check, top cylinder runs the fuel pump, you list it as new, but check this, remove pump from block, hoses still attached, pump the primer bulb, does fuel come out the bac of the pump?

Ok I pressure tested the entire system for a half hour, it bled off some in the handle but I couldn't find any leaks throughout the entire system.

 

[isuckatboats]

Videos — The Penn's Old Outboards

www.oldoutboard.com

I think the ohm reading for the for the secondary side (plug wire side) is a bit weak. Recalling from the Penn instructions, you should see 4 to 6 in a good coil with the tester set at 1K ohms. (Check the link. Hopefully, the reformulation still contains the instructions for measuring coils.)

Ok, I will swap coils for the cylinders this weekend and see if the problem follows!

 

[ct1762@gmail.com]

Sorry but getting back to your original post: you put epoxy where? And RTV has no place on an outboard... you didn't put any on the intake manfold gaskets right because those go on the same way you took em off... bone dry. Just checking to make sure you didn't plug any holes needed for bearing lubrication. the overheating on these (besided t stat) is usually because of LEAKING pressure relief rubber grommets... were those replaced or in good shape?

 

[isuckatboats]

Sorry but getting back to your original post: you put epoxy where? And RTV has no place on an outboard... you didn't put any on the intake manfold gaskets right because those go on the same way you took em off... bone dry. Just checking to make sure you didn't plug any holes needed for bearing lubrication. the overheating on these (besided t stat) is usually because of LEAKING pressure relief rubber grommets... were those replaced or in good shape?

I used RTV on the water jacket cover(over the heads) and on the connection from the impeller output to the main body of the outboard to help hold the coupling grommet in place, all other areas have aftermarket gaskets in place. I was sure to compare OEM gaskets to the aftermarket alternatives to make sure all the holes were in the correct locations. I also used the epoxy to bridge a failed area in the water jacket casting (it was allowing water to bypass the top cylinder head keeping it from cooling, this is also where the temperature sender is located). I believe these were necessary modifications to allow the motor to cool efficiently minus the fact i totally removed the thermostat to keep unrestricted water flow. I understand the implications of an engine running below operating temperature but this is just my fishing boat and i only require it to rev up to an exceptional level and idle.

 

[ct1762@gmail.com]

unfotnuneatly running it without thermostats is not an option. if its not cooling properly with it in, replace the poppet valve grommets. did you try a new thermostat and check it to make sure its opening at 143 degrees with warm water? old ones get sluggish and many times wont fully open until 170+ degrees!