Mariner 85hp 1977, dies when under load and throttle above 25%

[Crazy Professor]

Hi Crew,

My Mariner 85hp 1977 was running great till it overheated at low revs.

I replaced the water pump but it now will not throttle up when in the water and in gear.

We were slowly motoring out of the marina, i tried to get going faster and then the motor started to die. I dropped the throttle and it kept going but refused to go past about 25% throttle without dying. The prop was not inhibited, there was plenty of water coming from the tell tale. The fuel is fresh and most of the fuel lines are new. When we got back to the marina, it would rev up in neutral no problems.

I did notice that the cover over the fuel filter on the motor leaks fuel when I pumped the bulb. I could hear it when the cover was on. I took the cover off and checked it and found it leaking. Could it suck air into the fuel lines and cause this problem?

We put it on the trailer and i tried to rev it up in gear on the trailer to test the motor, and the same thing happened, died at over 25% throttle.

Any Ideas?

 

[Bondo]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

Hi Crew,

My Mariner 85hp 1977 was running great till it overheated at low revs.

I replaced the water pump but it now will not throttle up when in the water and in gear.

We were slowly motoring out of the marina, i tried to get going faster and then the motor started to die. I dropped the throttle and it kept going but refused to go past about 25% throttle without dying. The prop was not inhibited, there was plenty of water coming from the tell tale. The fuel is fresh and most of the fuel lines are new. When we got back to the marina, it would rev up in neutral no problems.

I did notice that the cover over the fuel filter on the motor leaks fuel when I pumped the bulb. I could hear it when the cover was on. I took the cover off and checked it and found it leaking. Could it suck air into the fuel lines and cause this problem?

We put it on the trailer and i tried to rev it up in gear on the trailer to test the motor, and the same thing happened, died at over 25% throttle.

Any Ideas?

Ayuh,.... Welcome Aboard,... Any abnormalities in the fuel system could cause a lack of power,....

Seein's it does it on the wagon too,... I'd also suspect the carbs need rebuildin' as well,...

 

[MH Hawker]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

If fuel is leaking out air is being sucked in.

 

[Chris1956]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

Well, That is a classic symptom of dirty or mis-adjusted idle mixtures. Did you do any work or adjustments to the carbs?

 

[Crazy Professor]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

Well, That is a classic symptom of dirty or mis-adjusted idle mixtures. Did you do any work or adjustments to the carbs?

I have not touched the carbs, or any other part of the power head, just changed the water pump.

Could the spark plugs have been effected when it overheated?

 

[Chris1956]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

When was the last time (before overheat trip), that the motor was used?

 

[little.boat]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

I would first replace the fuel filter you know is leaking. Take it back to the lake and tear it again. If it started to die out push your choke in and see if that makes the engine run. If so that means that your engine is flooding out and likely have a float stuck.

 

[little.boat]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

Also is your primer bulb staying hard?

 

[Chris1956]

Re: Mariner 85hp 1977, dies when under load and throttle above 25%

Little Boat, I am not sure how choking the engine will make a flooding engine run better. It will, however, make it flood more. If using the choke does allow you to get more RPM, then the carbs are dirty or mis-adjusted.