evinrude 50hp losing power?

[bigchunkytaco]

hi guys i have an evinrude 50hp, got it running well for an old one, i replaced a few of the lines cleaned carbs etc as they were a bit split and leaky, however recently when i throttle higher it kind of cuts in and out with power, the same way it did when it was starving of petrol before i replaced the lines, thats what it feels liek to me,

i also thought maybe the filter, it seems fine except for the outer diaphram looking a bit worse for wear? it almost looks like its a bit loose on the shaft, like the middle of the diaphram has worn away could this be the issue?
any other ideas?
she still starts first turn and runs fine at low speed just when i increase throttle past 60% or so....

 

[5150abf]

Re: evinrude 50hp losing power?

Could be electrical or the pump, I had mine with a short that would only kick in when the boat was bouncing at speed so maybe a rewire doing one wire at a time from the big red plug back.

Leave a good length of wire maybe 3'' long on the plug adn solder and tape all your connections.

Make sure you fuel tank is venting correctly and none of you fuel hoses are cracked from the tank to the carbs, everyone seems to forget that bit of line under the hood.

If none of that gets it I woudl lean towards the fuel pump, make sure the tube to the crankcase is open and unobstructed, the pump is run by pulses from the crankcase.

 

[bigchunkytaco]

Re: evinrude 50hp losing power?

i did think about the wiring, is it possible that the actual connection to the battery could be poor contact and intermittent bouncing around? or is it irrelevant once it has been started?

 

[5150abf]

Re: evinrude 50hp losing power?

Once it is running it makes its own power ut never disconnect the battery if it is, it fries the rectifier.

Mine was a wire that had a cracked sheath and it would run fine then cut out, then run fine, real intermitent and you say old but not how old, mine is an '81 and the wires were starting to crack so I just changed them all, I am big on aircraft type maintanence, change it before it fails.

If the wrong wire touches the engine body, which is negative it will short, not saying that is the probelm but it certainly can't hurt and you will probably save a problem down the road by rewiring.

 

[boobie]

Re: evinrude 50hp losing power?

Model # ???

 

[bigchunkytaco]

Re: evinrude 50hp losing power?

model #50303R but i am skeptical as to whether thats the plaque that matches the actual engine as that would make it 70's and i think it looks more 80's, the transom bracket could have been replaced at some stage but i assume they are still similar

 

[boobie]

Re: evinrude 50hp losing power?

Do a compression test and then a spark test. Spark should jump a 7/16 " open air gap on a spark tester. Basics first.