Outboard Engine Help

[gyroman]

Automan1223 or anyone else I need help!!!

I know this is cheesy asking help on my outboard motor in a rotorcraft forum but it is in the Off Topic section.


I have a 1980 60 HP evinrude motor that has been giving me fits. A little history: I had a burned piston so I had the engine rebuilt. When complete the engine would not go above 3000 rpm. Took it back to the shop and they found a bad powerpak. Since then I put about 20 hours on it with no problems at all.

Now my brother took it out and on the way back in the engine dropped about half RPM's. It only runs about 3500 on full throttle. The engine will start up on almost the first crank when warm and will run fine out of water. Put it under load in the water and only get about 3500 rpm. I tried a new powerpak again but no luck same problem.

Oh, and I rebuilt the carbs after this problem (no luck same problems) so no blockages anywhere and there's no real carb adjustment other than syncing the carb linkages.

Any ideas? Would a coil being bad cause this? Or something with the stator? Any help is greatly appreciated....

To make this more rotorcraft related I add the following:

What happens when a make a downstream turn close to the pier??? HEHE

And... if I get this boat running I can sell it to BUY MORE GYRO PARTS....

[Chuck Irby]

Toby, what are the compression readings?

[gyroman]

Compression was good... approx 140 in each cyl... still is checked it a week ago.

[Chuck Irby]

Toby, I am assuming that one cylinder is not firing and both are getting fuel. Is this correct? If so, yes, a bad coil could definitely cause the problem.

PS, did you check compression after the last problem?

[gyroman]

I swapped the coils around and it had the same problem, but in a two cylinder engine I guess that wouldn't make much difference. One would always be out. But if I remove the spark wire while running the engine quickly dies, no matter which cylinder I pull. (not to mention a nice shock when I do it.)

PS yes, compression is still good at approx 140psi.

[Chuck Irby]

Toby, something doesn't sound quite right. Are you saying that if you pull either plug wire, it'll quit?

[gyroman]

Yes the engine will die if either plug is pulled.

[Chuck Irby]

Toby, if both cylinders are getting fuel, both plugs are firing, and both cylinders have 140 pounds of compression, it should run like a new one. I'll give it more thought. Meanwhile, it wouldn't hurt for you to make sure that all of the aforementioned is, in fact, true.

PS, remove both plugs and make sure the engine turns over freely and smoothly by hand.

[gyroman]

I'll try to verify everything tonight if I have time. I know the compression is right cause I was worried about it the most. (You know spending all that money to find out it is screwed up again).

Appreciate all the help......

[Ron Marlett]

Toby
What year, make and model is this engine? Does it have a single ignition coil(with 2 plug wires coming out of it) or 2 completely seperate coils? Some 2 cylinder 2 strokes using a CDI ignition employ a single coil with each end of the secondary coil winding going to a spark plug. Both plugs fire at the same time(near TDC on one and BDC on the other). The circuit goes from one end of the coil secondary, down through one plug wire, jumps the plug gap and travels through the cylinder head to the other plug. The energy then jumps that gap and returns to the other end of the coil via the second plug wire. Removing either plug wire would interrupt the circuit and stop both plugs from fireing. And your body would absorb the energy giving you one hell of a shock .

Your 1/2 max RPM symprom sounds like a cylinder not fireing As I am sure you know you need Compression, Fuel, Air and spark. Sounds like you have good compression so you are missing one of the other 3 or you have too much fuel/oil on one cylinder and it is fouling the plug on that side.

What do the plugs look like?
Are you running Pre-mix or oil injection?

[C. Beaty]

Check the reed valves, Toby. Sounds as if you could have a broken reed in one of them.

A broken reed will make it spit back through the carburetor but if you always run with air cleaner in place, you wouldn't notice.

I don't know whether or not these engines have ignition advance linked to the throttle. It can be done electronically. If it appears to have mechanical advance and most likely it does, make sure that when you open the throttle, the ignition pickup (under the flywheel) moves with it. Retarded ignition prevents full power RPM and burns pistons.

[Chuck Irby]

Those are good thoughts, Mr. Beaty. However, I have never seen a stainless reed valve break. Have you? Too, it sounds like it's running too smooth for it to be a reed. I used to run fiberglass reeds, and could loose a small part of one, on a six cylinder, and notice it immediately. In addition, why would it immediately die with the removal of either plug wire? Something just doesn't add up, IMO.

[automan1223]

The first thing you have to check is the color and condition of the plugs. If a plug is not firing it will be 1 of 2 conditions,

wet soaked with fuel

or

black sooty fouled.

any outboard with a weak condition will display the power you describe.

once you check the plugs and have an idea what is going on if you have spark and they are not a shared igniton coil set up and you pull a wire and the engine dies then you got a bad coil somewhere. if this is a 4 cyl with 2 coils then you got a shared ignition and you could have the wires mixed each coil wire must go to the correct coil. output terminal.

If you have checked all the basics there are 2 obscure things.

well 3

fuel pressure sucking air in the lines causing low fuel supply


exhaust gasket leaking around power head inside the leg, a small amount of fumes will travel up the leg and choke up the engine. run with the cover off and see what happens.
I use great stuff to seal around the leg gaskets and the power head, most techs reuse the old gasket, its a pain and they never seal right anyway. They all do it and it is a primary why outboards have trouble starting and power output.
it cant make power if it is sucking exhaust.....

last problem is the worst requires teardown and heartache. there are carbon seals that seal the crank in the block between the cylinder chambers and if they crack or leak it will produce the symptom you describe. Most of the time on the tall boy merc outboards. since this is an evenrude then its still possible but the only way to know it is to have the whole thing torn down.

Check all your basics first. I have done A LOT of research on these engines. champion has a lot of new plugs that you can run and I got a tremendous amount of power out of my engine by going to extended core plugs. with correct heat range. throw a new set of plugs at it just for drill. 2 strokes are finiky

what plugs ?

how many cyls ?

Jonathan

[gyroman]

Ron,

The engine is a 1980 60HP 2 cyl evinrude. It has two separate coils per cylinder. I believe both plugs looked brownish/black and a little wet but haven't checked that in a while. I do remember they both looked about the same. I'll add that to the list of things to check. Should I let the engine run for a few minutes then cut it off and check the plugs?

Chuck,

I had thought about checking the reeds but I have to take off a lot to get to them which is why I procrastinated.

The carbs do have an airbox on the front so you can't look directly down the throats.

The engine does have the ignition advance linked to the throttle. When you increase throttle it does move a linkage which changes the timing. I guess I need to read up on how to check the timing on this engine but the shop book I have is not really that clear and the engine was working fine, just all of a sudden started having this problem.

Thanks all, gives me more items to check out....

[gyroman]

Jonathan,

2 plugs (think they are champion, I'll have to verify)

2 cylinders

2 coils

2 carbs

1 power pack.

It runs the same whether the top cover is on or off. I had it at the lake a couple weeks ago checking things out. I had my wife driving at about 2000 rpm and pulled a plug wire, almost fell outta the boat (from the shock) and the engine immediately died.

I'll try some new plugs this weekend but I think I did that a while back but certainly doesn't hurt.