Johnson 20 hp

[jamesh76]

I have the following motor Johnson Model# 20r72r. I had the coils, points, plugs, wires and fuel pump rebuilt or replaced. The motor starts up fine, Idles fine. When I go underway it runs great for about the first 50 yards or so and then it starts to cut out almost like it is not getting any gas. It cuts in and out. Then when I was at idle waiting to load it back on to the trailer it started cutting out while it was at idle. I almost think that the fuel pump is having issues but at this point I am uncertain. I have taken it to the guy that replaced the parts listed above 4 times already and am about to loose my mind. Any advice would be appreciated. Also if someone has a link to a site for parts for this motor I would appreaciate it. I have looked under ther parts menu here but unable to find parts for this year.

Thanks.

 

[bowman316]

Re: Johnson 20 hp

is the primer bulb on the gas line staying hard?

Try pumping it when it is about to die.

You replaced the fuel pump on the motor?

 

[jamesh76]

Re: Johnson 20 hp

The fuel bulb does stay hard. The guy that did the repairs said he put a kit on the fuel pump.

I have not tried to pump it when it is running. (can't right now its at the shop)

The engine has died but only at idle.

 

[tashasdaddy]

Re: Johnson 20 hp

did you remove the high speed jet and clean it, and the orifices? it is either that or did you adjust you carb? http://forums.iboats.com/showthread.php?t=167352

 

[bowman316]

Re: Johnson 20 hp

so the engine dies at idle, or only when you try to get up to full throttle?


If it is some form of gas starvation, it will idle ok, but when you give it more throttle, it will gradually die out, and you usually can back off the throttle when it starts to die, and it will not stall out and return to idle.

That will let you know it is a fuel delivery problem.

 

[jamesh76]

Re: Johnson 20 hp

It never died at full or 1/2 throttle. It only died when it was at idle.

It would sputter at full/half throttle but did not die.

 

[jamesh76]

Re: Johnson 20 hp

ok i got my boat back. The guy working on it said it was a bad spark plug wire. I got it home and put it in the barrel to do a little bit of testing. IT started up good, the bulb felt firm and it idled ok. I then brought up the rpms and then let off it idled down. I repeated this step and it died. It also died a couple of times at idle. I think it was idleing too slow. I then turned up the idle a little bit and seems fine. I will take it out in the morning to do a test under load. Is there anything specific I should look for if it starts sputtering like it did before?

 

[Howard Sterndrive]

Re: Johnson 20 hp

where do you have the idle mixture knob set?

 

[jamesh76]

Re: Johnson 20 hp

its pretty close to being in the middle. If i move it too much it does not idle or run very well.

 

[DannyO.]

Re: Johnson 20 hp

I had a similar problem. My situation was corrected when I

1. Shortened the hose between the bulb and the motor. It was a brand new fuel hose, and it was a lot longer than it needed to be.

2. I put more gas in the tank. It was sloshing around and sucking up air.