Motor Bogs down after WOT

[ledzeppelin135]

Hi, lately when I have been running my boat at wide open throttle it will get up on plane for a minute or two and then it will suddenly lose power and you have to decrease the throttle lever and run it at a little more than half throttle and if you attempt to speed it up, it will bog down and die. If you put it in neutral and rev the idle lever to full throttle it will get there and stay there but then putting it in gear will only allow it to go 1/4 throttle. After letting it sit for a random amount of time it will suddenly get back to normal for a few minutes at wot or for probably ten-15 minutes at 90% throttle. I decarbed the motor by putting seafoam in cylinders and spraying it in the carbs twice and that seemed to pick up the rpms with more weight in the boat but it also kept dying. I also replaced the plugs and it is still the same thing. I have not rebuilt the carbs as I dont have a repair manual but if you can walk me thru doing this or suggest anything else that may be causing this I would appreciate it. Thanks

 

[ledzeppelin135]

Re: Motor Bogs down after WOT

For the record this is a 1983 Mercury 50hp serial number 6308464. I am also wondering how I can determine which brand of carbs I have.

 

[fisherman81654]

Re: Motor Bogs down after WOT

For the record this is a 1983 Mercury 50hp serial number 6308464. I am also wondering how I can determine which brand of carbs I have.

This may help you determine which carburetor you have.http://www.marineengine.com/parts/m...+(4+CYL.)&serialId=5864&serial=5531630+AND+UP
Have you had someone pump the primer bulb as it starts to lose rpms at full throtle?
If that cures the problem,then you most likely need to rebuild the fuel pump,also check the fuel filter and make sure your vents on fuel tanks are open.
Seafoam,from what I have been told,will not help the carburetors,unless you are running the engine at a high rate of rpms underload or on water. I don't think I would use that method,to me it may be hard on the rings,creatting too much heat.Its best to rebuild the carburetors.I would (Never) rev the engine on muffs or in idle on water.
hope this helps ...

 

[ledzeppelin135]

Re: Motor Bogs down after WOT

i appreaciate the help, but I have tried pumping the bulb and it does nothing, fuel filter is good and the vent is open. I have taken the carbs apart today and the only part that seemed dirty was the first butterfly valve i believe it is the choke valve and all the other needles and openings and small litttle nicks and crannies seemed clean. What all does the carb rebuild kit consist of?

 

[fisherman81654]

Re: Motor Bogs down after WOT

i appreaciate the help, but I have tried pumping the bulb and it does nothing, fuel filter is good and the vent is open. I have taken the carbs apart today and the only part that seemed dirty was the first butterfly valve i believe it is the choke valve and all the other needles and openings and small litttle nicks and crannies seemed clean. What all does the carb rebuild kit consist of?

Well,You should have determined that the carbs was a problem before you took them off,but since you have them off,they need to be rebuilt,new gaskets at the least, the carburators need to be completely dissassembled and soaked at least over night in carb cleaner and then blown out with a air compressor.(They almost always look clean) but they can still have a restriction.
You should take a small wire and make sure all holes are open,being carefull not to make any holes larger than they are.

Make sure you have good compresson on each cylinder and fire on each plug and that no wires have been damaged inside the cowl.Diconnect the rectifier and try after you have assembled carburators back together.

You could have other electrical problems,but since you do not have a manual or dva meter,there is no way of testing properly.

As far as which carburator you have,I am not sure,from the site I sent you looks like the Walbro or Tillotson.When you order a kit,ask them.