View Full Version : Any old Merc experts out there????
I have a 1964 85hp inline six merc. It's one of the old white one's and I guess they only made the inline six for a couple of years, 63 & 64. Well here is the problem. I mix fuel, prime all three carbs, choke, start and let worm up. Take off choke and go. The motor idles fine and runs good, the boat just flies through the water. Then at full throttle it starts to slow down and finally it won't be on plane and just pushes through the water at about half speed while the throttle is still maxed out. The motor still idles and runs great it just won't go fast. It's like I need more throttle. The linkage is fine, the fuel tanks and bulb are new, I replaced the 2 diaphrams on the side on the motor, and I took off and cleaned the screens on top of all three carbs. So please help!!!!!!! Thank you, Ryan
letstroll
08-30-2002, 03:09 PM
I think you might have found at least part of the problem. If you can flood it out by pumping on bulb the needle and seat are not sealing to shut off the fuel. when you are running it probably is flooding out the carb and making it run way too rich (lack of power).
good luck, ray
I had a similar experience with an older outboard. The float in the float bowl was sticking due to some flotsam in the fuel. Might flush out the floatbowl(s). Allso fresh plugs cure 80% of the outboard problems ever encountered. At least that's the rule of thumb I have heard.
Well fellas, it looks as though we have it narrowed down a little. So any ideas where I can get a shop manual for this old beast. I don't think its anything electric or the plugs, because I'm getting spark on all cylinders and plugs are new, also idles fine. Which leaves this rubber hub thing that ReelMcCoy mentioned. Then there is the suggestion that letstroll had about the needle and seat. That sounds like it could be the problem also, but this motor has three carbs, are they all doing it or could this just be a problem with one of them. Thanks for the help, Ryan
[ 08-31-2002, 11:11 PM: Message edited by: ry ]
ReelMcCoy
08-31-2002, 12:03 AM
I am no outboard export. The thought that comes to mind at the moment is something that happened to me. My motor is a lot newer so I am not sure if it applies but the prop is mounted in a rubber hub. I needed to get it rehubed. It acted just like it ran out of power. There may be something wrong that is close to this area of the 1960 technoligies.
One thing you might try is to do a compression check when it is cold and when it is hot. It is real easy to do. The gage can be purchased at any parts store. Then all you need do is remove the spark plugs install the gage and turn the motor over three or four times with the starter. You should mark the plug wires to insure they are reinstalled correctly. The reason for removing all the spark plugs at once is in some cases there can be a leak between cylinders that will give a false reading. And it prevents the motor from firing. The reason for doing it both hot and cold is that there may be something warpping when hot.
This information is from my days as an auto mechanic.
Hpoe this helps and good luck.
thanks for the insight, this started just after I got it back from having the lower end serviced. However, when I shut it down and make sure the bulb is full, restart and it goes full steed again then just as fast as it went it slows down again. One more thing the vents are open and when I have it going and try to pump the bulb it fluoods out. Thanks, Ryan
[ 08-30-2002, 12:14 PM: Message edited by: ry ]
any other ideas out there