Evinrude E-NATION, for those dedicated to water, power, fishing and fun
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Mate
Posts: 2
Registered: ‎07-05-2020

Lack of power under load

I recently became the owner of a 1969 Evinrude Sportsman 155. It has the Buick "Nailhead" V6. We were told that the boat was lacking power and the thought was that it needed a valve or piston job. After sitting for about a year, it started right up in the driveway with the hose attached. Right away we could hear a tapping noise and suspected a valve issue. Upon further inspection, we found that the exhaust manifold had a small hole and when patched with high temp JB Weld, the noise went away and the engine for its age was quiet. We took it to the lake and began our first test run to see how it handled. The boat powered right up and went on plane and we were shooting across the water. Unfortunately, the fuel tank even though it was reading full, was empty. We ran it completely out of gas. Luckily a friend was with us and towed us in. The very next day, I took it to the gas station and filled up with 18 gallons of gas. We took it back to the lake to continue our test and for some reason, the boat would not go above 2800 rpm and would not go back on plane. We looked at the fuel filter and there was very little gas in the filter. More investigation found that the fuel pump was bad and the fuel filter had dirt in it. We changed the fuel pump and filter restoring the flow of gas to the engine. Once again we connected the hose and started it in the driveway. The engine ran strong, smooth and quiet. We could push the throttle open full and the tach pegged out at 6000 rpm. We decided to go back to the lake and test. We backed it in, ran at no wake for about 5 to 10 minutes, once the no wake zone was cleared, we throttled up but it would not go above 3000 rpm. After several up and downs on the throttle, back to neutral shifting forward and reverse and once again attempting the throttle up again, still no higher than 3000 rpm. Placing back in neutral, we did a throttle up again and it went up to 6000 rpm. Returning home, I figured that it was not an engine issue but maybe a Sterndrive problem since we had not changed any fluids yet. I did an upper and lower gear case fluid replacement. Both upper and lower fluids were a yellowish milky consistency. I replaced with Type 'C' lubricant and trecked back to the lake. Unfortunately, it was the same result. No more than 3000 rpm were achieved under load. In neutral however, full rpms. We rebuilt the carb, did a compression test (all cylinders are within range), back to the lake, still no help. I am at a loss, can anyone offer me any assistance as to why the boat would go up on plane and run fast until we ran out of fuel and now I can't get above 3000 rpm when in gear. 

Highlighted
Admiral
Posts: 9,379
Registered: ‎07-14-2011

Re: Lack of power under load

What numbers were the cylinder compression readings?

did you check each plug for spark at all rpm?

 

did the timing advance as the rpm increased?

 

 

 


"There is never just one thing wrong with a boat";
                    -- Travis McGee, main character in a book series by John D. McDonald 


 



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The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.


Highlighted
Mate
Posts: 2
Registered: ‎07-05-2020

Re: Lack of power under load

The compression readings were from lowest 125 to highest 150. We also found that the timing was quite retarded. We advanced the timing back to normal and I also drained, cleaned and refilled the fuel tank. Planning to take it for a run again hopefully today. There was quite a bit of dirt and a deteriorated gasket in the tank so that has all been removed. Hoping for the best. It just makes no sense that it ran perfect until it ran out of gas.