1995 Johnson 48 SPL/48 hp Revs. Up and Down

[GROSK]

1995 Johnson 48 SPL/48 hp, 2 cyl, 2-stroke

To start with, motor sat up for a year.

Changed : impeller, spark plugs, lower unit fluid, TNT fluid, New fuel Tank, New Fuel lines - from tank to fuel pump, and from fuel pump to each carburetor. Carburetors, and fuel pump seemed to be clean, though cleaned each, and installed New kits to each, just to know what I had. to be on the safe side.

Very good spark to each plug, plug gaps, and carburetor linkage are right on the dot.

Checked to be sure Spark Advance plate moves freely with no sticking.


At first put on the muffs, motor fired up very first crank, idles perfectly.
Shift into forward or Reverse barely reving the engine, it went to speed up, though did not get to full speed. I guess the best way to explain what it sputters like, is as if it had a Rev. Limiter like some automobiles have. as in keep in park, and floor it only revs. up and down, without a steady acceleration.

Tried it out on the water, thinking maybe this motor does this only when running on muffs, though same-thing. (barely 5 MPH) Wide Open.

Even Double Checked that the vent on the fuel tank was opened. and just to be sure even though tank is New, thought vent perhaps may not have vented as it should so, also removed the fuel cap, while running.

Checked to be sure the choke solenoid, was positioned right. (parallel with the solenoid, as pointing away from it only chokes and kills the engine)

So I went ahead checked and did just about everything, as stated above.
Same scenario. Fires up very first crank,Idles perfect, Stills Revs. back n forth with throttle wide open, on Muffs, and on the water.

I've searched this forum over and over for about a week, days and nights at times, also Read the FAQ, the Secrets and all. lol

I've found some posts with almost similar problems, though that was another problems, lots of ideas on what to check. As I've already done, before finding this forum. Though I noted that, it seems most people Never post the solution to what they have done to fix the problem.

So I'm in hopes that whom ever may have had this problem or Similar problem, wouldn't mind sharing what they have done to Solve their similar problem.

Great Informing Ideas will be appreciated.

 

[ezeke]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

Sounds like you may have an air leak somewhere in the fuel system.

Check the fuel pump membrane and the carburetor to intake gaskets.

Put a little steady pressure on the primer bulb and look for leaks; if gas can get out, air can and will get in.

 

[tashasdaddy]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

check your throttle cam roller, they are 2 piece, the outer covering tends to crack and fall off. creating play in the throttle linkage.

 

[GROSK]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

Fuel pump was redone with kit, also changed the carb. to intake gasket at time of re installing the carbs. Though I did go try squeezing the primer bulb very hard just to be sure on leaks, No-Leaks other than eventually coming out of the carbs. (Flooding).

Also forgot to mention that I have warmed up the engine, and checked compression on each cyl. Reading a 120 on both.

I also just now checked that roller and the one at the carb. linkage, cause was another Good thing to be sure of. and that too seems to be fine.

I'm thinking of making a short video of the engine running, and what it does when going to WOT. and then Post the link to my video. Just in-case I'm not explaining what its doing, in an understandable way. Its basically like and automobile Rev. limiter. but a vehicle I think would only do it being floored.

This engine does it, at medium speed 1500 rpm. all the way though WOT.
though starts, and runs good at idle. and the best thing, is either way- wide open or not, it never chokes down or Kills.
Of course it kills only when the key is turned off.

This engine is getting to be really confusing, lol

But again thanks for you guys help. What ever becomes the solution to this problem, I will be one member to post what had to be done to fix the problem. for the knowledge of others whom may end up with this problem in the future.

 

[ezeke]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

Squeezing the bulbs should not have flooded the carbs, that's what the float valves are there for. You may have found your problem though.

 

[GROSK]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

well I mentioned flooded, but what I meant really was. It was coming out of the side hole of the black plastic on top of the carb. I'm guessing its an over flow?
Cause it does the same on both carbs. rather than just one.

 

[GROSK]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

<<< BUMP>>>

 

[bob johnson]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

check your throttle cam roller, they are 2 piece, the outer covering tends to crack and fall off. creating play in the throttle linkage.

you know there was a recent thread in the last few days where guy posted pictures of his motor, and that missing sleeve was obvious in the picture!!, i thought about mentioning it.

 

[tashasdaddy]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

sure sounds like you need to adjust the floats. there should absolutely no gas coming out of the carb. the only time they may overflow, is when the motor is tilted up, as that throws the floats out of level, then it leaks out the carb throat.

 

[GROSK]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

well I got that over flow problem fixed. Yes had to adjust the floats, just that tad bit off, allowed air to flow through when attaching a hose to the carb, and blowing into it. No longer fuel over flow, when pumping the bulb even as hard as you can squeeze it.

Though even though the rollers seemed ok. I still replaced with New ones.

Basically rebuilding this Motor little by little, lol but ....

STILL having the problem with it not picking up speed when going to WOT.

Still acting as if it has a Rev. Limiter, still Starts and Idles Perfect though.
Just cant get it to pick up speed for anything.

 

[GROSK]

Re: 1995 Johnson 48 SPL/48 hp Revs. Up and Down

Well found the problem Guys/Gals...

I noted two wires on the terminal bar, had slight rubber melted. So that would show a possible weak/ No connection of the two wires. For them to be arcing enough to melt the rubber of the terminals.

Sort or say, had a weak connection to supply enough current to idle fine, though not enough current at higher speeds as needed.


Buffed-up the terminals, put them back in place. attached muffs, and Purrs like a new little kitty.


I new it couldn't be much. but still don't understand how that didn't throw off the timing. (during timing check)
Back to running good, all that matters I guess.

 

[Justinlaw81]

Do you have any pics of the wires you fixed I'm having same issue

 

[GA_Boater]

Do you have any pics of the wires you fixed I'm having same issue

He won't be coming back after 6 years just to take a pic for you. You could start a new thread.

Closed.