1987 15 hp johnson stalling J15RCUD

[lummer]

I have to manually prime it to keep it running but it still runs high then low. I changed the gas tank and have a new line on it but still does it. If I don't prime it it will simply stall out. Any suggestions?


Johnson Model 1987 J15RCUD

 

[the machinist]

Re: 15 hp stalling

Re: 15 hp stalling

You don't mention what year the motor is, sometimes this helps us identify the problem.

However from the sounds of your problem, it appears you have a fuel delivery problem. This could be the fuel pump or fuel lines to/from it or a dirty carburetor.

 

[xtremefisher1]

Re: 15 hp stalling

Re: 15 hp stalling

Put up your yr make and model and model # so you can get more accurate help.

Sounds like you have a bad fuel pump if it even has one. Also if it doesnt you might have a vacuum leak somewhere that it isnt pulling the fuel from the tank.. I beleive that those motor are a vacuum system. So u need to keep the tank sealed so it can have pressure in it to put the fuel threw to the carb.

Someone else might chime in if i am wrong but without the model numbers you wont get a definate answer

 

[lummer]

Re: 1987 15 hp johnson stalling J15RCUD

Any new suggestions? I see that a fuel pup kit is pretty cheap so I may just try that.

 

[JDusza]

Re: 1987 15 hp johnson stalling J15RCUD

Welcome to the forum.

Agree with the machinist and xtremefisher1. Fuel delivery problem. And, engine history with you will help us understand better. I wouldn't throw part money at it. Take the time to troubleshoot it.

Is the engine new to you? If so, there's some simple maintenance to do to make this enjoyable and stress free: carburetor clean up and water pump impeller replacement, etc...

There's two fuel paths within the carburetor, low speed path and high speed path. This sounds like your high speed path is blocked or you have an air leak somewhere.

Or, if not new to you, have you performed any maintenance on it? When's the last time the carburetor was gone through?

J

 

[lummer]

Re: 1987 15 hp johnson stalling J15RCUD

it is fairly new to me and has been doing it since I got it . I took apart the carb and thoroughly cleaned it. It seems to be a fairly clean motor for its age. It has new spark plugs, a new hose from take to motor. Last year it seemed to run fine for after it fussed for awhile and ran for a bit. I ran some carb cleaner in the last tank of gas as well.

 

[JDusza]

Re: 1987 15 hp johnson stalling J15RCUD

OK.
Hang in there. This is a great engine and will serve you for years to come.

When talking about "sealing" the tank as mentioned by xtremefisher1, it should not be air tight. This is a single hose vacuum system not a double hose pressure system. The fuel tank vent cap must be opened so air can replace the removed fuel,. If not, a vacuum is created in the tank that wants to keep the fuel from traveling through the lines. Be sure your tank vent is open.

What do you mean it "runs high then low"?

Next, we'll evaluate the carburetor. For this we need to know which one you have . there are a couple available for his model; one with a plastic top and one which is all aluminum. We need to know.

There are two paths the fuel will take within the carburetor; high speed path or low speed path.

How does the engine run at mid to high speed? Will it stay running and stall at low speed or does it stall at high speed as well? You can manipulate the throttle cam follower by hand to rev the engine and see if maintains mid to high speed running. If it does not, then you have an air leak in the fuel path, a blocked high speed main jet in the carb or blocked fuel filter, or bad fuel pump.

If it runs at mid to high speed and stalls at low speed, then you have a problem in the low speed circuit of the carb; low speed jets blocked, low speed needle out of adjustment.
When you did carb maintenance, did you reem the low speed jets? If you did not, then you can have junk floating around and replugging the low speed jets over and over. You blow them clean, you think they are clean and the symptoms reappear 'cause the junk isn't really removed.

Let us know which carb you have and we'll take you through it.
J