1989 Johnson 50 HP Pro Series

[sigeforrest]

I have a Johnson 50 HP Pro Series that was not getting gas to the lower carb. After taking both carbs off and cleaning them twice I am now getting fuel to run out if I leave the drain screw out and prime the tanks. But the motor still will not hit over 2000 rpm or idle correctly. Are there other things I should be looking at or is this a problem with the high and low speed jets. This motor has been sitting for some time with the old gas still in it but the previous owner stated that it ran well before storage.

 

[WillyBWright]

Re: 1989 Johnson 50 HP Pro Series

Welcome to iboats. <br /><br />Get rid of the gas and try fresh. I've seen gas so bad it wouldn't burn. Don't mix with fresh gas. Just get rid of it.

 

[sigeforrest]

Re: 1989 Johnson 50 HP Pro Series

I have completely changed the gas and put new tanks in. This a oil injected motor but I did not change the oil yet. But would that affect how it idles and throttles?

 

[Lubosleftboot]

Re: 1989 Johnson 50 HP Pro Series

The oil will not affect the way an engine runs but if the motor has sat a while it might be worth your time to change the spark plugs as they degenerate with age.

 

[reeldutch]

Re: 1989 Johnson 50 HP Pro Series

did you buy it recently?<br /><br />did it ever run propper for you?<br /><br />what are your compression numbers and do you have 7/16" bleu crispy spark on both plugs ??<br /><br />also check for link and sync every time you take the carbs off.<br /><br />good luck

 

[sigeforrest]

Re: 1989 Johnson 50 HP Pro Series

I just purchased the boat and it has been in a garage for about 6 years. Tonight I picked up a couple of carb kits and rebuilt them. I also changed the fuel filter and spark plugs. We were able to get the motor to idle strong at 1000 rpm. The problem now is that it cuts out at 1500+ rpm. If you drop it back down to idle speed it runs fine. The water pump and everything is working good, it just seems that it is struggling for fuel. Could this be electronical? Any suggestions?

 

[fireman57]

Re: 1989 Johnson 50 HP Pro Series

Check for spark when the rpms drop. You may be running on one cylinder. Check the coils for cracks. If you can run it in the dark you may see some arcing off a bad plug wire.

 

[sigeforrest]

Re: 1989 Johnson 50 HP Pro Series

Thanks for the feedback and I will try that maybe tomorrow when the weather breaks. But after reading some other post, is it possible that the thermostat or fuel pump may be failing? It just seems like something is telling the motor to not go above a certain rpm so it cuts down to one cylinder or something. Also found that idle speed should be around 800 +-30 so I need to tune that down a little as well.

 

[Silvertip]

Re: 1989 Johnson 50 HP Pro Series

The engine may be going into SLOW (safe) mode which limits RPM by interrupting spark. A VRO or overheat problem can trigger it. Does the alarm horn sound when you turn the key on? If not, start there. Won't solve the problem, but at least you get that working. Feel the engine when it acts up to make sure it is or is not overheating. Did you totally disassemble the carbs, clean every passage and jet thoroughly and blow them out with compressed air? If not, you may still have a fuel problem.

 

[sigeforrest]

Re: 1989 Johnson 50 HP Pro Series

Continued in "How to check for a damanged thermostat"