1971 50hp 500 power problem Looses power.

I

idahobrett

Recruit
Joined
May 15, 2009
Messages
4

Hello to all the Members.
I have this problem with a 1971 Mercury 500 50 hp.
I bought boat went out and it run at top speed "great"
for awhile, it seems like after I have stopped 2 or 3 times.
Then next time I try and go its only half power.
I thought maybe water was getting to lower cylinders.
I relaced water pump and all manifold gaskets including the head place water
jacket gasket. The base gasket looked good.
I went out this morning same symptoms.
I notice small posible moisture when pulling bottom plugs.
I pulled the lower end this morning the exhaust tube seems loose at top when pushing up in place. I wonder if there should be a gasket up there, but cant see one on the parts view. Is it possible moisture is getting in from there?
If it was carburation I would think it would act up all the time?
It runs fine the last time then you slow down or stop and thats when it only goes half power.
I'm really lost and dont want to start replacing stuff thats not needed.
Any help would be greatly so welcome .

Brett in Idaho
 
F

fly4fish

Cadet
Joined
Feb 26, 2009
Messages
8
Re: 1971 50hp 500 power problem Looses power.

Did you have fully charged batterys when you first went out? I have a 1978 merc 1400 and i just replaced the rectifier (it relays charge to the battery) I was having the same prob, I would charge my battery and the boat ran great but the more times i stopped and fished it would start lossing power and it would also get harder to start. i wasnt getting a hot enough spark. Might take a look at it. that is if you have a rectifier that is. good luck
 
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