Help with Merc 9.8

Discussion in 'Bubba's Outboards' started by Alsey, Jul 30, 2006.

  1. Alsey

    Alsey New Member

    First off, let it be known that I don't know Jack about outboard motors. I bought my first boat yesterday. It came with a 1971 Mercury 9.8 hp and a 1976 Mercury 7.5 hp. Both motors have been maintained well. The man I bought it from has had health problems lately and has given up fishing. He handed me the owners manuals for both motors when I picked the boat up and they look brand new.

    Anyways, the 9.8 hp motor has been sitting up for a year and a half or better and the 7.5 hasn't been run in 8 months. The seller said he came out and pulled the starter cord every month to keep the engines from seizing up but neither one of them were started during that time.

    I launched this morning with the 9.8 on and it ran pretty bad from the get-go. It wouldn't get up to speed and would only run smoothly while at idle speed. I put the 7.5 motor on and it ran pretty rough and also had problems getting up to speed. After I ran the 7.5 awhile it started running alot better.

    I've been told I have varnish in the carb and it needs to be cleaned and the plugs and some other part need to be replaced.

    If anyone could give me some solid advice on how I should proceed I sure would appreciate it.
  2. Bubbakat

    Bubbakat New Member

    Jim The one that hasn't been run in about 8 months you might get by with just running some seafoam thru it but the other one needs to have the carb taken off and soaked real goo and then rebuilt. Bobpaul has a good illstration on here that gives you the basics of doing that. I will see if I can come up with a diag of those carbs for you. It ain't no biggie you cand do it if you can turn a wrench. I would replace both impellers at this time to and replace both fuel lines from the tank to the engine and did you dump the old gas and add new fuel with a 50:1 mix.

  3. Iowa_Josh

    Iowa_Josh New Member

    Central Iowa
    New points! And get an extra impellar they are really fragile. Carb kits don't cost that much. And replace the old gas lines they aren't that long maybe 2' total and they just crapped out on mine it is 70's also. A little hose leak is all kinds of problems. has the stuff you need all you need is a serial number to figure out what to order.
  4. Bobpaul

    Bobpaul New Member

    Supply NC
    If your not sure you want to tackle the water pump and carb rebuild on these engines, then get them to a shop.

    It should cost you no more than 2 hrs labor and about 50.00 in parts for each engine.

    Water pumps on these little guys are a snap to do. The carbs are a little tricky, but no real problem.

    If you decide to do it, invest in a manual and have a ball.