Motor runs rough

[Slayerh]

I have a 1986 Evinrude 88spl. I recently took it out and it was running great. I gave it more gas and all of a sudden it seemed to choke out and sputtered, but didn't shut off. Since then it has been running rough. I did notice the started wire had lost it's nut and sparked when I got back and was diagnosing it. Seems as though it is missing pretty bad. It starts up fine, but idles rough and won't get up to speed. After a period of time, it seems as though it is trying to fire up and go. It eventually will speed up and accelerate, but is still not right. I recently pulled the plugs out and looked at them to see they seem rather fouled and caked with black sutt. Could this be the problem? I have replaced a lot of things on this boat in the past year including: entire fuel system, lines, filter, new fuel pump, rebuilt the carberators, put brand new spark plug wires and new spark plugs in. Suggestions?

 

[racerone]

Re: Motor runs rough

A compression test needs to be done first !!

 

[Slayerh]

Re: Motor runs rough

A compression test needs to be done first !!

I did a compression test afterwards and all four cylinders read 100 on the compression test.

 

[emdsapmgr]

Re: Motor runs rough

That compression is normal. When that engine idles, the plugs are overfueled-so it's normal that they will appear, wet, even oily when checked. It's a different story if you were to check them after running 5000 rpm's for a minute-they will be tan in color. Likely your engine has an ignition problem. Check for spark after the engine is fully warmed up-weak ignition components tend to work ok prior to the engine warming up to normal operating temps. Two running tests you could try: a cyl drop test or use an inductive timing light on each plugwire. Either will tell you if you have good spark while running. Those coils are generally pretty reliable, so the other three main ignition components become primary suspects in this order: power pack, stator and timer base. If you find that you have bad spark on one cyl, you can do an easy test: That engine does have dual power packs-one for each head. Swap the power packs and see if the misfiring moves from one head to the other. If so, replace the bad pack. Are you sure your engine is not an 87? OMC first started making the 88 in the 87 model year.

 

[Slayerh]

Re: Motor runs rough

Well I thought it might be something crazy since the choke out happened so suddenly. I actually took both carbs off afterwards and cleaned them again to ensure they didn't suck something in. It is obviously missing and I have pretty much ruled out fuel problems. I think it must be a spark or fire issue causing it to miss. I will get some new spark plugs first and change the fuel filter again to see if it resolves the issue. I have read some threads about fuel hoses collapsing and causing a fuel delivery problem but I'm not so sure that's the issue.

 

[boobie]

Re: Motor runs rough

Sounds like an ignition problem. Read post # 4 again.

 

[Boss Hawg]

Re: Motor runs rough

Well I thought it might be something crazy since the choke out happened so suddenly. I actually took both carbs off afterwards and cleaned them again to ensure they didn't suck something in. It is obviously missing and I have pretty much ruled out fuel problems. I think it must be a spark or fire issue causing it to miss. I will get some new spark plugs first and change the fuel filter again to see if it resolves the issue. I have read some threads about fuel hoses collapsing and causing a fuel delivery problem but I'm not so sure that's the issue.

Could be way off but just had the same issue with my '87 110- after I went through most all you did/replaced (pulled my carbs twice also)
I went back & did a complete link 'n sync mostly out of frustration because I couldn't think of anything else to do-- problem solved! - Only takes a couple turns of a nut/screw to really make a difference.

 

[Slayerh]

Re: Motor runs rough

Well i swapped out the power packs to see if it was an ignition issue. Didn't seem to make a difference. I also had a spark tester that I tested all four plugs with. All showed to be putting out a spark. I did find I had a blown fuse on a connecter wire leading from the cylinoid back to the power packs on the one side. I replaced it and it "seemed" to make a difference but it still isn't running smooth.

Is it possible for it to be out of time? I can't see this as the boat ran like a champ for 30 minutes before it broke down and started running rough.

How hard is a linc & sync to do an do I need any special tools?

 

[emdsapmgr]

Re: Motor runs rough

It's possible (however unlikely) that the flywheel key has sheared. That will make the engine out of time-all 4 cyls. Usually when this happens, tho, the timing is so far out of whack, that it won't run. Period. Would be very unusual for it to slip just a few degrees..permitting the engine to run, but roughly. You can check the flywheel by: 1. Check the idle timing on #1 cyl when running. 2. Index the flywheel against the timing pointer- a static procedure from the factory service manual. 3. Pull the flywheel off and see if the key is sheared. The blown fuse won't affect the engine when it's running. It will stop the starter from cranking, the choke solenoid from working and will probably prevent the trim from functioning.

 

[Slayerh]

Re: Motor runs rough

Ok so I apparently wasn't checking the power packs like I thought. I was checking the wrong thing. So after further review of the symptoms, here is what I have:

Motor is missing bad. I pulled all plugs out to check for fluid. Both plugs on the right side were wet with fluid. Both plugs on the left were dry as a bone.

I swapped power packs from one side to the other this morning to see if it made a difference in which side was wet or dry. I swapped them and started the motor and let it run for a bit. I then pulled the plugs again to check for wet or dry. Seems as though the plugs on the right were still wet and one plug in the left was now wet.

If the power packs are working, should the plugs be dry or wet?
Also is there a visual check you can do on the power packs? Seems as though the back of one I could see metal or something through the black. The other was solid black on the back.

Any suggestions are appreciated.

 

[racerone]

Re: Motor runs rough

The real test for spark is a open air spark tester set to a gap of 7/16"----------A good ignition system will jump that gap with ease.--You should be able to hear the " snap, snap , snap " when cranking the motor over.

 

[emdsapmgr]

Re: Motor runs rough

That engine overfuels slightly at idle. Normal thing. Plugs that are dryer are firing. Very wet, oily plugs are not. You've been given a couple of ways to check for firing, posts #4 and #11. Suggest you try one of them...

 

[Slayerh]

Re: Motor runs rough

Yesterday I replaced the power pack on the side that did not seem to be firing the plugs. After doing so, the motor ran like a champ and did not mis.

Thanks for the suggestions and help!