1995 70HP Evinrude perplexing problem

Last fall I bought a pontoon boat with the 95 70hp Evinrude, model # E70TLEOR. This summer I started it up with ears on, and everything seemed fine. But after putting in the water and taking it for a ride, the engine will not start once warmed up. Leave it rest for several hours in cool weather, and it may start. Generally if I let it sit overnight it starts.

Symptoms: Runs fine once started. Can run it for hours with no sign of a problem. However, if it is turned off it will not start when warm. When you try to crank it over, it fires and may cough on what seems like one cylinder and then stops. Tried starting it with the throttle at different positions, and it does the same thing.

Here is what I have done so far to locate the problem
- fresh gas and oil
- cleaned all connectors and grounds, including removing the CDI and coils to clean ground.
- changed fuel filter
-changed plugs
- emptied carb bowls
- sprayed carb cleaner when it ran (when engine was cool and started)
- sprayed fuel in the carb -did the same thing, coughed when starting warm
- checked for spark when it wouldn't start; there was spark on all plugs
- sprayed freeze spray on CDI, coils - Engine still coughed until let sit overnight.

If it happens to start when warm, which it will do once in a while, it runs fine. But turn it off and immediately try to start it, it coughs on what seems to be one cylinder, and stops. Because it tries to fire I generally can't crank it long, a second or two before the starter is disengaged.

One strange thing happened last night. A buddy of mine came over to have a look. While the problem was occurring with the cover off, we noticed when it was coughing, the flywheel seemed to pause a spin backwards before stopping (if that makes any sense).

At this point, I believe it must be ignition since spraying fuel in the carb made no difference. Anyone have any additional tests I should do before I purchase a CDI powerpack?

 

timing light on the flywheel and check it but first check the pointer incase you have sheared the key and the flywheel has moved
You can do that with a piston stop or even a long reach plug screwed in, just wind the engine each way by hand, half way between where it stops is where the pointer should be.
You can even divide the wheel up and check the timing on all 3 but rare to have ignition issues on a 3cyl.

 

When you say it won't start, how long was the starter cranking when you tried ? This talk of a cough and a splutter and the starter disengaging, sort of suggests it is a battery/starter problem.

 

Hi Everyone. Thank you to those who responded to my post for help. This morning an old friend with plenty of experience with outboards stopped by and we discussed my symptoms. He agreed with me that it was ignition related and not a fuel issue. He just happened to tell me about another engine he was currently working on, and it would miss when warm. Not exactly the same, but he told me that someone had put grease/oil on the spark plug cables, and changing them cured the problem.

Today is very hot weather, and when I tried to start it, it wouldn't start. Cough, sputter and stop. So I pulled off the ignition cables and did a continuity test. The first one was nearly zero ohms. The other two I found it difficult to get a reading. I had to really hunt around for a good contact, but got a reading with low ohms. Looking at the connections on the cables they looked dirty and oily. I had previously changed plugs, and cleaned the primary and secondary terminals on the three coils, but I never changed or cleaned the spark plug cables. So I cleaned them with steel wool, contact spray and a cloth. Put them back on and the engine fired up like a champ.

Took it for multiple rides and turned it off several times over several hours. Each time it fired up without a problem. I probably should have tried to fire it up after dark to see if there was any sparks when it wouldn't start. My spark plug tester uses a neon light, so I can't tell how strong the spark was when I had tested spark previously. Anyway, at this point in time the problem seems to be resolved. I wanted to post this outcome so that others can benefit. The cables were easy to clean, and it may be a step others want to take when weird things pop up with hot starts. I would have never thought the cables would be the cause of this problem, but will accept the solution.

 

Hi Mr. E. When the problem occurred, turning the key to start position started cranking the engine, then the engine would fire and the starter motor was just spinning freely (hopefully that makes sense). Holding the key in the starting position would not crank the engine unless you turned the key off and tried again. This would happen seconds after starting to crank.

 

Is the battery good ? I know sometimes the starter won't engage properly if the battery is a bit weak.

 

It should be relatively easy to get hold of the workshop manual for this motor, and consult the troubleshooting section. Ignition system checks may require a cheap electrical tester you can get at an auto accessories shop. This beats the pants off scratching your head and swapping around parts on suspicion. I do know though, that I have had similar problems in the past that were fixed by a strong battery that got the pinion engaging properly. It might be the case that when the starter pinion and the flywheel gear get a little worn, you need to have battery and starter motor at peak performance.