1978 Evinrude 115 sporatic problem

[TonyinKY]

First, I'm new here and I appreciate all internet sites where a wealth of information can be shared to help out others in need. Some I can contribute to and others I just learn from. I'm here to learn so "Thanks!" in advance.

1978 Evinrude 115 model 115899
I've only used this boat a few times per year for the last ten years.
The problem started about 8 yrs. ago.
Every great once in a while it would not take the throttle taking off.
This became more often over the next several years.
I had the carbs cleaned one summer and it seemed to fix it for one trip?
But the issue returned and became more sporadic.
Sometimes it ran great for an hour or two.
Then it would not take the throttle on take off and just bog down.
I had the motor rebuilt because of low compression.
The sporadic performance continued but it does run better when it runs.
It always starts and idles great.
Sometimes it takes off great and runs up to 5k and bogs down to 4k and then picks up again.
Sometimes it runs like a new motor.
I put a new fuel pump on it Sat. morning.
Took it to the lake and it was running great.
Pushing in the choke would kill the engine.
So I figured I was getting plenty of fuel.
I stopped for about 1/2 hour.
The motor started fine but would not take the throttle.
Anything above about 1200 rpm would bog down.
The choke would kill the engine.
Pulling off any plug wire while idling would kill the engine.
I'm thinking I may need new power packs?

[ttles714]

fuel

Most times what you describe is fuel... Are you running on a built in tank ?? there is a screen on the pick up tube in the tank that may be clogged or debris in the tank which may be intermittently blocking fuel flow to the pick up..... try running off a separate 6 gal tank.....

[TonyinKY]

Fuel?

I am running off a built in tank and I haven't tried a separate tank. From what I've read I thought that choking the engine while running would increase RPM if it was fuel starved and stall/kill the engine if there was sufficient supply of fuel. Is that wrong?

[TonyinKY]

Fuel issue eliminated

I took the boat out and used a different fuel supply and got the same results.
Anyone have any suggestions on what to try next?

[Solarman]

Sounds like timing advance is not working all the time, intermittent. What controls timing on your motor? Is it a trigger coil that turns/advances from throttle linkage? In parts its listed as timer base and sensor ***y. If manual gives a test, check this, and check for any damaged wires from it.

I'd look up parts for your motor, but since the site changed their parts page I don't get the diagrams, can't see parts breakdown now.

Post back, when able.

[TonyinKY]

Timing? I agree

I agree it sounds exactly like a timing advance not working correctly at times. I don't have a manual to check for that system.
Here's the schematics.
1978 Evinrude 115899C 115 hp Outboard Motor Parts

[Solarman]

Thnx for diagram. I would look for a test of item #30, and check the wires from that unit, possibly grounding/ shorting if wires are worn from movement.

You might be able to google testing for that part number with item name. There may be a you tube video on testing that ***y.

Good luck.

[TonyinKY]

Found a repairman

My brother has recommended someone who says he can test the items and do the labor for one hour ($75) and is reasonable on his parts prices. I let you know how it turns out. Thanks!

[TonyinKY]

Fixed

This motor has been repaired. It was the stator. It had a burnt spot in one of the running coils.

[Solarman]

Glad you're up and running again.

Appreciate the up date on your problem.

Happy boating!