Mercury 1977 70 hp 3 cylinder

greasemonkeyozi

Petty Officer 1st Class
Joined
Jul 16, 2003
Messages
282
One day I was out on the lake, and my motor was running very good until I had suddenly lost all horsepower. I had ran a compression test to see if I had a burned out piston, all checked out around 145 psi. I had then replaced my swich box,reset the timing, cleaned out my 2 carborators, and checked to see if my fuel pump is still pumping good. Everything checks out, but still no horsepower. Somebody PLEASE HELP!!!
 

NathanY

Commander
Joined
Mar 16, 2002
Messages
2,408
Re: Mercury 1977 70 hp 3 cylinder

So is the motor still running, with no power? Not running? Will it just idle and then die when you put it in gear? Need more info.
 

greasemonkeyozi

Petty Officer 1st Class
Joined
Jul 16, 2003
Messages
282
Re: Mercury 1977 70 hp 3 cylinder

Well, to be specific, She Idles like a champ. Like a kittin purring. But whenever she's in the water, no accelleration at all. She bogs down real low and if you throttle it down too much, she dies.<br /> Like I said, so far I have changed all plugs, my swich box, made sure my coils are ok, heck, im getting perfect fire on all 3 cylinders, I have replaced all old wiring,replaced some fuel lines, and reset the timing.<br /> After I did all this, I put her in the water, and she had the same problems, but, after a while of playing with the throttle, I had slowly got her to accellerate to the high speed it was suppose to. After she got warmed up, I could be at a dead stop and accellerate like there was no problem.<br /> I stopped to do some fishing, just long enough for the engine to cool down, she fired right up.When I went to take off, there was no accelleration. The same problem acted again except this time, I couldnt get her to accellerate at all, just bogs down.<br /> This weekend, I'm gonna replace the fuel pump diaphram, really clean my carbs with a fine tooth comb again, replace my floats in my carbs,replace my carb gaskets,recheck the timing,and replace all fuel lines with new hoses.<br /> I'm not too sure how the fuel diaphram works, but I'm pretty sure I'm getting sighns of a fuel problem.<br /> I also had a guy tell me to take the pins out of the carbs and the seats, and make sure no trash is in them. I did take the pins out and blew on them with a air compressure and had perfect flow, but didnt inspect for trash.I'm gonna do that this weekend as well. <br /> Maybe you can give me some more advise on what to do or replace. Hopefully its just something minor.
 
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