1969 20hp chrysler outboard chugs

[Goseeboat]

I have a 69 chrysler outboard that I just bought for my kids fishing boat. It has electric start and fired up & ran & shifted great when tested(when I bought it).

Now that I mounted it on the boat it seems to have a misfire or chug when it is idling and sometimes at full throttle.

50-1 mix on the gas, spark plug is new.

Any ideas please?

 

[wickware]

Re: 1969 20hp chrysler outboard chugs

Is that mainly when the motor is cold and it goes away? My 1970 35 hp Chrysler is cold natured in 80 degree weather in TX. 95% of the idling problem goes away when the motor warms up. I have a good thermostat but get instant water due to the impeller lubricating. Bumping my idle rpm up is the only help I have found and it might sneeze and stall once or twice before it levels out.

A slight richer idle mixture might help (the only one mixture screw in my case). I h/n played with mine in a while since my 1984 purchase but I feel it was less of a problem then.

 

[Goseeboat]

Re: 1969 20hp chrysler outboard chugs

It seems to happen when cold and after running for a while.

 

[wickware]

Re: 1969 20hp chrysler outboard chugs

Any history that might lead to needs or any adjustments? Such as: Last Tune-Up Inspections (points condition), carb cleaning/inspection, fuel pump and diaphragm inspection, fuel tank, lines, quick coupling inspection X trash or air leaks (clear fuel filter just before carb), last impeller change and etc time well fitness.

 

[Goseeboat]

Re: 1969 20hp chrysler outboard chugs

No idea of the history; I bought it a couple weeks ago. I may check the points; Seems that may be a good place to start based on reading some other threads.
I know there was 130 psi on both cylinders.

 

[wickware]

Re: 1969 20hp chrysler outboard chugs

In this week?s North, TX heat at 6AM we did not need a purge/prime or choke. The 1970 35 hp Chrysler started with a nice even rpm and never died or sneezed. The heat makes a difference because the purge and prime is basically there from the fuel expansion from the movement in the heat (d/n leave an open line on a 6 gal tank). Trolling was all we could do in the low lake except climbing onto the trailer with a higher rpm (it did both well).

A good tune and good airless fuel connections makes a big difference. With engines this age it takes some care and monitoring. My fuel pump?s diaphragm h/n been changed ever that I know of vs checked. The bad part was I h/n planned to fish the low lakes this season. Two pics of catches had me registered and 4 trips in 4 weeks. Now I?m done with a few-to-no fish. We caught enough in the 80?s for a lifetime vs more fun. More stump damage to repair!

If you are in the North, TX lakes, be careful in the low lakes and high heat.