Mariner high speed issues

[scruffy_fish]

This question is still pluaging me. I have a 50hp 4 cylinder '84 outboard that will run all day at ideal, but when I take it over 3200 rpm it will begin to bog and eventually need to be dropped back to lower rpm or stall out. I let it ideal for a while then it responds beautifully until it goes over 3200 rpm again and repeats this all the time.

I have gone through all the vacuum possibilities, re bulit the carbs and new fuel lines. It seems like a gas starvation issue. Any one ever experience similar?

 

[j_martin]

Re: Mariner high speed issues

This question is still pluaging me. I have a 50hp 4 cylinder '84 outboard that will run all day at ideal, but when I take it over 3200 rpm it will begin to bog and eventually need to be dropped back to lower rpm or stall out. I let it ideal for a while then it responds beautifully until it goes over 3200 rpm again and repeats this all the time.

I have gone through all the vacuum possibilities, re bulit the carbs and new fuel lines. It seems like a gas starvation issue. Any one ever experience similar?

Try pumping the primer bulb when it's acting up. If it helps, it's a gas problem. If it doesn't, it's electrical, probably high speed stator winding.

hope it helps
John

 

[scruffy_fish]

Re: Mariner high speed issues

Thanks for the reply, I'll try that. This has been bugging me since I rebuilt the carbs.

 

[j_martin]

Re: Mariner high speed issues

Thanks for the reply, I'll try that. This has been bugging me since I rebuilt the carbs.

What did it do before you rebuilt the carbs?

I used to train computer field engineers. The hardest thing to get them to understand is this:

If you walk up to a running machine, do something to it, and it now does not run.....................IT'S WHAT YOU DID TO IT.

Wrong cable, bent pins, card in the wrong slot, you get the idea.....

hope it helps
John

 

[scruffy_fish]

Re: Mariner high speed issues

Has been acting like this ever since I bought the boat. Acted like it was starved for fuel. I thought that rebuilding the carbs and new fuel lines would cure it. I runs great at low and trolling speed and it has just enough speed to get me around.

But, I often want to open it up to clean out the carbon and know I should be able to get more than 3200 rpm out of this motor. Hadn't thought about the high speed stator. Didn't realize there was one. I'm a shade tree mechanic with a manual and a wrench.

 

[scruffy_fish]

Re: Mariner high speed issues

While still tiring to find the starving fuel issue I checked all the vent tubes to see if they were clear. I used a probe wire to check the tank vent and hit an obstruction. I then used compressed air to clear the line and found, someone had stuffed a cigar into the vent line. A perfect trick to dive someone crazy.

With the cigar gone and the vent clear and the boat in storage for the past two years, I now have a marine mechanic looking at the issue. He seems to think the carb floats are the problem, after checking off other potential issues.