1975 Evinrude 85hp boggs down at full throttle...Advice needed

[Type-X]

Hi All,
This is my first post on this forum. After countless months trying to fix my problem, googleing the internet, and ruined fishing trips at the lake, I have decided to ask YOU the boating experts for help. Here's what I have:

Boat/Motor: 1980 Monarch 17ft w/ 1975 Evinrude 85hp

Problem: At full throttle, the motor boggs down. It idles fine and runs fine at low throttle. Some times it work in full throttle and sometimes it doesn't. Not sure when it will work or not.

Things I have done to the motor:

1) Replaced fuel lines (except primer bulb, it works since I can feel pressure when fully pumped)
2) Replaced Spark plugs
3) Replaced impeller
4) Cleaned out both carburetors
5) Ran a spark test and the spark is good
6) Compression is good at 120 psi for all cylinders

Side note:
I have found metal shavings in my lower unit and the seals are bad since I have found water mixed with the oil too. I have changed the gear oil but would a bad lower unit cause these symptoms?

Please let me know what you guys think and help me diagnose this problem. Any help would greatly be appreciated.

 

[willard887]

Re: 1975 Evinrude 85hp boggs down at full throttle...Advice needed

From what you said I believe you still have a carb problem. Possibly something is getting in one of your high speed jets. Those are the jets behind the bowl drain plug. But maybe someone else might have a better opinion. There is a possibility that you have a bad wire under the flywheel. But I'm no expert.

 

[Type-X]

Re: 1975 Evinrude 85hp boggs down at full throttle...Advice needed

Any encountered simulare problems?

 

[Autotech1]

Re: 1975 Evinrude 85hp boggs down at full throttle...Advice needed

Have some one pump the fuel line bulb while the engine is bogging. Could be bad fuel pump.

 

[Type-X]

Re: 1975 Evinrude 85hp boggs down at full throttle...Advice needed

Do these motors even have fuel pumps? I thought it was just the primer bulb and the fuel pressure came from engine vacuum. Correct me if I'm wrong please. Forgot to mention I am using a portable tank for fuel since the internal tank needs to be cleaned.

***UPDATE***
I took the boat out last night and it bogged at high throttle as usual. When I turned off the engine, It was hard to start and wouldn't idle. I sprayed some carb cleaner in and after the fourth spray it started idling. I started the boat up again and put it into full throttle and again it starts bogging at full throttle. After about 10-15 seconds later (at full throttle) it was as if something got unclogged, cause the boat surged forward at full speed. It bogged slightly here n there while on plane. But these are the symptoms when it finally does decide to work.


-Any clues as to what's causing this. Can it be the needle valve not moving when it should?

 

[Type-X]

Re: 1975 Evinrude 85hp boggs down at full throttle...Advice needed

Well I figured out the issue. Just wanna thank those few who actually spent some time to add a suggestion. This is for all those guys that have a similare issue with their outboard and have been pulling their hair out the past few months trying to figure things out only the find the guy posting the problem never bother to reply if the problem was fixed or not. I pulled out the carbs again and did a thorough cleaning this time. Pulled those two circular metallic covers off ( the ones inside the carbs. Not sure wat the technical term is. If someone knows what it's called please post up) and found a piece of plastic in it. Cleaned everything out and reassembled and sure enough...NO MORE BOGGING!!!

 

[classiccat]

Re: 1975 Evinrude 85hp boggs down at full throttle...Advice needed

Congrats on finding the culprit (hiding under a welch plug)...and good job closing the case!! :thumb:

any idea where the plastic originated?