1967 Johnson 6hp won’t idle or stay running

[Kralldaddy]

I have a 1967 Johnson 6hp CD-24 that starts fine but doesn’t want to idle and dies about 10-30 seconds. It was in storage for about 20 years, but ran fine when stored and was properly winterized when it was. Has fresh gas, new tank, new fuel lines, the fuel pump is only letting air pass one way, but I haven’t taken it apart yet. (Heard that is a bear). Looking for any trouble shooting pointers. My dad has handed down his boat and engine to me to make some memories with my kids, so I’d love to get it back on the water. Thanks in advance.

 

[racerone]

If it has not been looked at for 20 years the coils are likely shot.----Pull the flywheel.---The fuel pump is easy to repair / inspect in my opinion.----Does motor keep running if you operate the manual pump ?

 

[Crosbyman]

you did open the tank vent
Johnson (leeroysramblings.com)
Johnson (leeroysramblings.com)
Rebuilding the OMC Fuel Pump (leeroysramblings.com)

pump rebuilds are tricky...but ok after a few !

 

[Kralldaddy]

If it has not been looked at for 20 years the coils are likely shot.----Pull the flywheel.---The fuel pump is easy to repair / inspect in my opinion.----Does motor keep running if you operate the manual pump ?

I’ll try the manual pump and see what happens.

 

[Kralldaddy]

you did open the tank vent
Johnson (leeroysramblings.com)
Johnson (leeroysramblings.com)
Rebuilding the OMC Fuel Pump (leeroysramblings.com)

pump rebuilds are tricky...but ok after a few !

Vent is open on the tank, it is one of those scepter plastic ones, but seems to working correctly

 

[rowerowe101]

I have a 1967 Johnson 6hp CD-24 that starts fine but doesn’t want to idle and dies about 10-30 seconds. It was in storage for about 20 years, but ran fine when stored and was properly winterized when it was. Has fresh gas, new tank, new fuel lines, the fuel pump is only letting air pass one way, but I haven’t taken it apart yet. (Heard that is a bear). Looking for any trouble shooting pointers. My dad has handed down his boat and engine to me to make some memories with my kids, so I’d love to get it back on the water. Thanks in advance.

Have you done spark/ compression test?

Sounds like carbuertor to me.. Have you adjusted idle screw / cleaned carbs?

 

[Harry B.]

Is there a high and low speed adjustments on that old of a motor on the carburetor?
Does it sneeze and cough before dying?
I'd muck with that first to see if it will idle with some adjusting. Turn the needle valve in all the way but not too hard when it bottoms out and then back it out a turn and a half and go in or out from there.........I believe is the adjustment rule.

 

[oldboat1]

I would not run that motor any more until the water pump impeller is replaced. Following that, let it run in a tank with water about half way up the leg. The top of the head should remain warm, not hot.

You can use a 50:1 gas to oil ratio on that motor (2.56 oz 2-cycle oil for each gallon of gas) -- round up, rather than down.

You can buy inexpensive fuel pumps these days (small square ones), and I would do that to see if your running issues are corrected that way. The carb has a needle on top for idle adjustment (air/fuel). After the engine warms up, slight adjustments might improve idling.

 

[Kralldaddy]

Have you done spark/ compression test?

Sounds like carbuertor to me.. Have you adjusted idle screw / cleaned carbs?

Haven’t messed with the carb yet, I’m going to eliminate one problem at a time, first will be the fuel pump, carb adjustment is next. Thanks

 

[Kralldaddy]

I would not run that motor any more until the water pump impeller is replaced. Following that, let it run in a tank with water about half way up the leg. The top of the head should remain warm, not hot.

You can use a 50:1 gas to oil ratio on that motor (2.56 oz 2-cycle oil for each gallon of gas) -- round up, rather than down.

You can buy inexpensive fuel pumps these days (small square ones), and I would do that to see if your running issues are corrected that way. The carb has a needle on top for idle adjustment (air/fuel). After the engine warms up, slight adjustments might improve idling.

So the water pump was done before it got stored, and it pumps nice while it runs, I have gas measured at 50:1, fuel pump is first on my list, if that does, improve things consensus is carb adjustments next. Thanks

 

[racerone]

There is only a low speed mixture adjustment.----Check the thermostat.----They often stick open.----And replace that impeller !

 

[rowerowe101]

Haven’t messed with the carb yet, I’m going to eliminate one problem at a time, first will be the fuel pump, carb adjustment is next. Thanks

Do what you want, just saying it's about 10x easier to adjust idle screw then start messing with the pump. And in my experience 90% of the time its the carbs. especially if its been sitting for 20 years, regardless of winterziation.

 

[Kralldaddy]

Thanks for the reply’s, life got in the way and I finally got time to work on the motor. Founds hair line crack in the plastic cover to the fuel filter. Replaced that and it’s running like a top. Time to make memories with my boys.”
View attachment IMG_2191.MOV

 

[oldboat1]

sounds good -- but need more water!