50hp dies under load

[mfo]

I have an 89 50 hp that i have had for about 2 yrs motor looks and for the most part run like new . I did a leak down on it when i first got it and it was about 2% even when it was cold! now thats perty good. Anyway i took her to the lake over the weekend and was runnin her around as this is one of the few places i can open it up and all was fine I have a a 6ga. portable tank and i was running low i prob only had about a gal or less so i had a 2 gallon can with reg can so i thru the right amount of oil in the tank for the 2 ga. poured her in shook her up and away we go . I ran her around for just a short time and was coming back into the dock when I heard her cough . I turn the motor off and when I went to leave again she started fine but would immediatly dies when i tried to advance the throttle to go , i started it again and the same thing happed again and again , i goosed her once and managed to keep it going for about 20 sec. Anyway this is a motor that has been starting a little bit harder lately but once it has been run it will always start right off with the first turn of the key. I think i heard her cough once a little bit last time i had it out before this happened , That cough and harder starting is the only thing that might have been a tip off that something wasn't right. Can anybody tell me what is the 90% most likely cause of this, something i can check out myself. I changed plugs about a month ago to the same plug that was in there , I pulled both plugs when i got home they are a little greasy but perty clean ,but not like they have been steam cleaned like with a bad head gasket. I have always put in some seafoam in every tank . Is this a fuel pump issue?



thanks
mark

 

[eurolarva]

Re: 50hp dies under load

Are you sure the motor did not overheat? When you restarted was the bulb still hard?. I would replace the fuel pump diaphram but before doing it I would let motor cool for a couple of days and re start in lake or a test tank and see if it runs alright. You may be flooding or motor is too rich.

 

[mfo]

Re: 50hp dies under load

I don't think it overheated new water pump and t/stat last yr. althoI think force seems to always run hot. The buzzer didn't go off

mark






mark

 

[roscoe]

Re: 50hp dies under load

If it sneezed/coughed, it is a classic sign of running lean.

Also, if it is running rich, it will stumble ... then accelerate when you give it throttle.

If running lean, it will die when you give it throttle.

Turning the idle mixture screw counterclockwise 1/4 turn will likely fix it.

Or, perhaps it is time to rebuild the carb and set it correctly.

 

[mfo]

Re: 50hp dies under load

ok here is an update. I pulled the cap on the fuel pump and replaced the screen altho it looked perfect like everything does on this motor and then i checked the position of the low idle screw. I read where it should be out 1 full turn and then a little more, hell mine was only out 7/8 of a turn from seated! also it must have been this way for the 2 yrs i have owned it. So with out running it I turned it out 1 full turn, I have a 40 gal tank I run the motor in I have never tried to run it in gear hopefully it doesn't throw out to much water it is kinda cramped in there. I have always run about an ounce/gallon or so of seafoam in my tank and it has always run fine. This time I was real low on gas in the 6/gallon tank so i stuck 2 gallons in there but "I DID NOT ADD ANY SEAFOAM THIS TIME" Could that have been masking a lean condition all along?


mark

 

[eurolarva]

Re: 50hp dies under load

A lot of force motors have a common set on the mixture adjust around 1 full turn. If you run the motor mainly WOT this adjustment is not going to play into effect except at idle. The best way to test is to gun the throttle from idle. If it hesitates and then goes it is too rich. If it dies it is too lean. Another indicator would be the way the tips of the plugs look. They should look slightly wet with an oil residue on them.

 

[mfo]

Re: 50hp dies under load

that is just the way the plugs looked. It is awful funny this problem started after i failed to put in seafoam this time.




mark