1994 48 SPL Evinrude Idle Question

Discussion in 'Bubba's Outboards' started by m-192, Jul 1, 2020.

  1. m-192

    m-192 Active Member

    Messages:
    229
    State:
    PA
    Name:
    Dan
    Hey guys I have a 1994 Evinrude 48 SPL on my 21' Pontoon. I just bought the boat this January. The guy I bought it from said the year before the carbs were rebuilt, plugs changed and a steering cable was replaced because the place that did the work broke it. I pulled the Plugs they do look brand new. The outside of the carbs looked really clean. However I am having a problem. It will run fine at higher speed but when I try to idle in forward or reverse it will run 5-10 seconds and shut off. No missing or rough idle or anything. It fires right back up. When I start it I got in the habit of lifting the starting throttle lever because it wont always stay running it just shuts off. Like I said no missing or rough Idle. I run 50:1 with penzoil marine oil I use 93 Octane and Ethanol Fuel that I put some marine stabil in. I thought it was the gas when I bought it but since then I have put around 48 gal through it. Its odd. Some times it will sit and Idle no issues or nothing other times it wont but 98% of the time if I try to Idle in gear I've only got maybe 5-10 Second and it shuts off. I did not check compression yet. Every free second I get I get it on the water Haha. Maybe tonight I'll check the compression and plugs and make sure the plugs are firing good. Also it drips a little bit of oil from the prop not much just maybe 3-5 Drops over a week after parking it. 2 Stroke oil as its black and smells burnt and the gear case oil is full and clean. Any Ideas? Right now its not a huge issue just a inconvenience. Thanks.
     
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  2. twaskom

    twaskom Administrator Staff Member Administrator Supporting Member

    Messages:
    10,195
    State:
    Indiana
    Name:
    Tom
    Dan, send Trophy Flathead Hunter a PM. He has a Johnson 48 Spl. He just had a similar problem with it and has just got it fixed. He can give you the details.

    Hope he can help. He is at work so give him a little time.
     
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  3. Trophy Flathead Hunter

    Trophy Flathead Hunter Well-Known Member

    Messages:
    1,300
    State:
    Indiana
    Name:
    Jon
    Here I am.

    Mine had trouble firing up. Things that my buddy and I did were flip one set of reeds that needed it , cleaned out the carbs, and change the plugs.

    We found that a small leak was coming out of the top carb, it ended up being a washer, it was just wore out so he replaced it I believe.

    It will fire up after 2 or 3 trys now instead of several attempts. I believe thats all we did to the motor. Hopefully this can help you out somehow.
     
    Last edited: Jul 1, 2020
  4. prlwng

    prlwng Well-Known Member Supporting Member

    Messages:
    1,825
    State:
    south dakota. sioux falls area
    Name:
    bill
    You may also have bad fuel line. Ethonol has been known to make the boat fuel lines colapse inside.
     
  5. twaskom

    twaskom Administrator Staff Member Administrator Supporting Member

    Messages:
    10,195
    State:
    Indiana
    Name:
    Tom
    Dan, this video gives an excellent explanation on what reed valves in a 2 cycle motor do. I would suggest watching it just to learn about them.



    Jon's motor had the carbs (2 each) cleaned also but Dustin, the mechanic that did the work said they were not really dirty. There was a screw with a washer that was leaking that was maybe allowing extra air to get into the system. They replaced it. Anyway it is starting better and idling better. Before it was not at all dependable for getting you back to the ramp.

    Good luck.
     
  6. m-192

    m-192 Active Member

    Messages:
    229
    State:
    PA
    Name:
    Dan
    I Messed with all the throttle linkages (tightened all the slop out of them) and adjusted the low speed idle screws and the idle rpm screw. Haven't had any issues with that since. However The Prop that is on the boat was a 3 Blade 12.25" 15 Pitch Prop. Worked OK ran about 15-16MPH. Going down river with the wind I could sometimes get almost 18MPH. I put a Tach on the boat and found out that it would run around 3500RPM WOT around 14-15MPH....Now I did add bigger fuel tanks so instead of 12-18Gal of Fuel I carry 28Gal now and a couple other things that added some weight so that lowered my speed. But occasionally while going WOT it would all of a sudden rev up to 4200rpm and slow down to 10-11MPH. I assume it was ventilation. But after getting the tach I realized I was over propped. So I ordered a 4 Blade 11.25" 10Pitch Prop. First trip out I had to be careful, if I gave it to much gas right at 5200RPM it was like hitting a Rev limiter. No problem I just had to watch the Tach and not punch it too fast. However the top speed at 5000rpm was 8.5MPH. That is unbearably Slow. The place I launch to the Lock is around 7 Miles up river. 8.5MPH wont cut it. I was fishing a lake when I found this out so it was not a big deal. However after boating around all day I was on my way back to the dock. I started giving it gas and I thought to my self "hmm seems like I'm going faster than I did all day." I looked down and was revving about 3200RPM and going 10MPH. I was like "what the heck" so I slowly gave it more throttle until I couldn't give it anymore and it was at 5000RPM and ran 14.5MPH. The only difference is I had used about 8 Gal of gas during the day. It ran great though. So my trip this weekend I am going fill it up with fuel and load it down(I will have a little more weight as this is a weekend cat fishing trip) see if its back to 8.5MPH with that weight . If so I will mess with the Trim and the motor height and see if that makes any improvements or not. Sorry for the long winded post.