Boat dying upon acceleration

[dirtracer11382]

Okay finally got my boat running pretty good today i big step compared to what ive been having to go through. Its a 1970's 85HP Merc 850. here are the list of all the problems which point to one thing. Okay upon first starting it have to try for a while to start it then it fires up stays running. throughout the day as long as the engine is warm fires right up. now today on the lake everytime i tried to open it up it would bog down and die. if i ran it in gear with very little gas goes fine. after running it this way for about 10 minutes i opened it up and it ran excellent. WOOHOO i was so happy... my friend wanted to tube so i killed it to let him get in the water. when i tried to start it again it fired but died whenever i woudl give it gas while it was in gear so i putted my way to the docks. Now when i use the primer bulb i get very good hardness in the bulb but sometimes the bulb will not suck up enough gas to fill itself back up so it stays collapse. Its a outboard motor so the tank is just one of those portables and it is older then most people that use this website (from a 1961 johnson). All things lead me to think vapor lock what do you guys think? <br /><br />thank you very much

 

[dirtracer11382]

Re: Boat dying upon acceleration

ALso forgot to mention this but running the motor out of the lake (dont worry got one of those fin thingies on there so the water pump can suck in water) and i put it in gear and give it full throttle runs pretty good.

 

[joblo33]

Re: Boat dying upon acceleration

Sounds like vapor lock except I'm not sure why it would have gone to WOT after warming up. It should have just bogged and died. Did you have the air breather open on the tank? If so try with the gas cap part way off in case the breather isn't working but I'm guessing it won't be as simple as vapor lock if you got it wide open after warming it up. Probably carburation. If it doesnt work with the cap off take off the carbs and clean them with carb cleaner and compressed air if you can.<br />Eric

 

[dirtracer11382]

Re: Boat dying upon acceleration

could it be that during that ten minutes running at low speed that what ever vapor lock occured went away by itself and then came back after i killed the engine and restarted it? just wondering like i said an old tank so there is no vent on it... maybe just enough vent on the cap for air to get in while i was just putting around for that ten minutes

 

[MortenH]

Re: Boat dying upon acceleration

Is the primer bulb hard after running? How about the fuel pump? And it will probably be time for cleaning the carbs. <br /><br />-M-