1993 Evinrude Crossflow 115 runs rough

[chopperguy]

Been through a lot with this outboard. I'm about ready to give up. Has brand new ignition system including stator,power pack, regulator and plug wirers. Piston broke off in #1 cylinder. During the repair they put in new piston and all rings replaced because of bad carbon build up. Carbs are thoroughly cleaned. Ran great until now. I even tried putting new reed valves in. Video link attached. Motor coughs and runs rough at lower rpms, but runs like a champ at 3000 rpm and up. Now it will barely idle. Any suggestions would be appreciated I am out of ideas and almost out of money.

 

[racerone]

What are the compression readings today ?--------New rings were installed on the old pistons ?

 

[chopperguy]

Compression in the 120s all cylinders

 

[schematic]

double check the coil wiring. Could have wires crossed.

 

[jimmbo]

Start with the basics. check things like spark plugs for gap, fouling, cracked insulators. Ignition wires for arcing to ground. Hook up an inductive timing light to see if the is an Ignition drop when the misfire occurs. spraying a gas-oil mix with an atomizer can rule out a lean carb. Possibly dirt in the low speed circuit of one of the carbs. You said it ran great till now. Did it run fine after the repair, or fine until it needed repair?

 

[chopperguy]

It started after the repair, but was intermittent. It is getting worse now.

 

[jimmbo]

It runs rough until the carbs start to open? Once the carbs start opening it runs fine? I mean when it is in gear under load, not on the muffs

 

[chopperguy]

It does it on muffs and in the water at above 2500 it stops

 

[jimmbo]

I suspect you have one carb running lean on the idle circuit. maybe a leaking gasket or hose

 

[racerone]

Plastic float bowls ?----Have they been checked to see if they are warped ?

 

[Faztbullet]

Air leak causing severe lean condition on 1 cylinder(transfer cover my guess)or carb problem on single cylinder

 

[chopperguy]

Ok, thank you all for the suggestions. Here's the latest. Mechanic that did the work said he checked timing and adjusted. Never popped until they did the work. I check the timing and at the idle stop the timing was slightly above TDC on #1. I advanced the timing to about 6 BTDC and the popping has gone away but not completely. Can someone please provide me the proper timing procedure and link adjustment?

 

[ondarvr]

Pull the cover off the front of the carbs, while it's running put your hand over each carb, if it's running lean, or if it's a carb issue, it will frequently stop popping, or at least change it enough so you can identify which carb or cylinder has an issue.

 

[chopperguy]

Already tried that only two carbs. It didn't stop popping.

 

[jimmbo]

Timing is set for maximum advance, once the carbs are synced to the timing advance it is the retardation of the timing that controls your idle speed. Adjusting the timing at idle speed is really irrelevant. I suggest you acquire a manufacturers service manual for the timing and sync proceedure

 

[chopperguy]

Ok, I am familiar with the max advance setting. I did it once. Had my wife drive while I was hanging over the stern with the timing light. So the only way to check timing is at 5000 rpm? I've never had a mechanic take my boat out to set this. Do you know how to do this without taking the boat out?
​Also is the 4 deg BTDC at idle a valid check?

 

[chopperguy]

Ok, I am familiar with this. I did this once with my wife driving while I was hanging over the stern with my timing light. So the only way to check timing is at 5000 rpm? Do you know how to do this without taking the boat out and running 5000 rpm
​Also, is the 4 deg BTDC a valid check at idle?

 

[racerone]

The most mis-understood concept is " idle timing "-----This is the point where throttle plates start to open.-----So it is a carburetor / linkage adjustment !---You adjust throttle control so that engine is at the 4 degrees.---Then stop engine to make the throttle plate adjustment.

 

[chopperguy]

Ok, I understand the idle timing is idle linkage adjustment. Is there any safe way to check max advance timing without having the engine screaming at 5000rpm? I assume you cannot do it in neutral. Is being underway the only way to do it?

 

[jimmbo]

Shops use dynos or test wheels in water tanks so they can rev up the engine under load