Johnson Stinger Part power Full Throttle

[fishondeck]

First ever forum post and first ever bass boat, If not doing this right, let me know and I will comply. I did not find any threads with info to help.

Sunday I purchased a 1988 Bumble Bee v 154. It came with a 1977 75HP Johnson Stinger outboard and Johnson command Center throttle.

Sunday before I purchased, we cruised all over the lake to test the boat. It started right up, and easily achieved 30 mph as a top speed.

Monday I took the boat out myself, it started right up , however, when at full throttle, it will not exceed 10mph. Keep in mind this is the very next day, right after it performed perfect with the seller. I admit, that with my limited experience being a new boat owner, it could be something stupid that I am overlooking or not doing properly.

I stayed on the water for a few hours and I went over everything that I could fathom to be an issue. I even took the shroud off the engine and confirmed that the throttle was actually fulling engaging to its furthest point.

The only thing I did before taking it out was add 5 gallons of 87 octane gas and mixed oil 50:1 .

After scouring the internet and you tube before posting this the only person that I have heard describe this issue is someone who had spun a bushing in the prop. He decribed it almost exactly. I just don't find it likely that that happened being that our last run Sunday was perfect and my first run yesterday did this.

I am open to any suggestions and will answer questions the best that I can . I would rather be missing something simple like an idiot than have a legitimate problem. I did call the seller today to ask and he has not replied yet.

Also, I do realize that I probably should have put in a higher octane gas. With that said, I can't see that contributing to the issue either.

THX

 

[flyingscott]

Compression and spark test need to be done. You could be running on 2 cylinders.

 

[johnyrude87]

this might be a silly answer but did u remember to open the vent on the gas cap?

 

[fishondeck]

Compression and spark test need to be done. You could be running on 2 cylinders.

Thank you for the reply. I understand that this is a good place to start but it just seems weird to me that it ran perfect, literally just the day before.

 

[fishondeck]

Not a silly answer at all because, actually, I did not vent it. I thought about it but the gas cap is solid with not vent. I took that to mean that it is not necessary. Am I wrong? Is there some other way to vent? Could not venting cause it to act this way.

I understand how not venting would cause it to bog and stall but that's not what it is doing. It was just consistently under-powered and refusing to get on plane or speed up. . Thanks for replying.

 

[racerone]

Just like beer varieties there are many different fuel tanks.-----The very good steel tanks that OMC used to provide were vented as follows.----When the hose is plugged into the tank you push in 2 little pins.----One pin is a valve that lets fuel out.----One pin is a valve that lets air in / out as needed.