1954 Johnson QD-15 Bucking in low idle

[mpetrucco]

I am new to outboards, and just picked up a few motors (long story), a '54 10 HP (QD-15), a '57 7.5 HP (AD-11), and a '48 5-HP (TD-20). I grew up fixing motors, but have been out of it for 20+ years. I plan to work my way trough these to try and get them running well.

I ran the 10 horse in a test tank this weekend and it is sort of bucking/backfiring at idle when in neutral, runs pretty smooth at higher rpms. Has anyone seen this before? Is it possibly an ignition issue or should I look elsewhere?

Also, after running in the tank (garbage can) for about 10 minutes or less, I was really surprised at the amount of oily sludge that accumulated in there. I know some oil is normal, but should I be concerned about the amount? I was concerned I had either some lower seal issues or other problem to chase down.

Thanks

 

[flyingscott]

Try adjusting the low speed mix screw a little richer could just be a lean sneeze. A Lot of oil on the water is normal run the motor at 24-1 gas mix.

 

[Crosbyman]

http://boatinfo.no/lib/johnson/manuals/1922-1964johnson.html#/0


this book will give you all the info you need for your motors ... the AD is a great motor

if it is your wish thay are easy to switch to modern fuel pumps and single hose applications

you will have to start with basics.... compression, ignition rebuilds if coils are cracked, new points and adjusted...carb cleaning, etc...

the book CHEAP OUTBOARDS is a great read...

 

[mpetrucco]

OK. Thanks. I am gearing up to do all of these. I will be switching both to a fuel pump and have two Mikumi pumps on order. Now I am looking for gasket sets for carb , etc. One thing is I need to find a source for drain/fill screw washers. Not sure where to find those. I don't see any leakage and LU oil looks good but there are no crush washers at all.

 

[lindy46]

Crush washers:
OMC 311598
Sierra 18-4248-9

 

[flyingscott]

0311598 is the part # for your washer used for a lot of years.

 

[Weirdboymike]

Great motors. I agree with Flyingscott. I just went through this on a '54 15 hp evinrude. I just adjusted the low idle to the richer side and it cured it. I think its firing too quick. Increasing the fuel to air ratio slows it down. I also have an AD-11. I love that thing. Just got my 15 so the 7.5 is still my favorite so far, but that might change when I get the 15 on the water this weekend.

 

[mpetrucco]

Thanks guys. I think it was actually just gagging on its own exhaust. It runs like a champ on the boat. I am near done doing ignition, carb, and water pump on an AD-10 ('54 7.5 hp). I can only seem to get a few minutes here and there to work on it. But it's getting close.

 

[Crosbyman]

the mikuni square pump version worked fine on my QD but i found it cumbersome... I much prefer the round version which is dirt cheap and I found it easy to install ​more solidly but you need to get a pulse and block the pump nipple behind the carb

more expensive but the best yet is the BRP/OMC standard square pump mounted over a aluminum plate on the top inspection cover. no other mods need except blocking the pump pulse nipple behind the carb. a piece of hose and a screw will do



use the cover as a template plus .5 inches all around. drill the plate inline with the pump'S rear end pulse port ... drill the cover

3/8 inches to let the crankcase pulses to reach the pump. use the same cover bolt hole alignement to mount the plate and bolt the pump on the plate itself ..don't forget the rear pump gasket !!





sorry purists :facepalm:​

 

[mpetrucco]

Thanks Crosbyman. I am having a hard time visualizing what you wrote.What inspection cover do you mean?

 

[I B Dead Eye]

No Title

I also have a QD15 it's a great motor and easy to work on. There is no need to switch over to the single hose and fuel pump. Just seal your fuel tank and replace the O-rings at the fuel connector. Rebuild the carb and make sure you replace the fuel filter on the carb. Don't trust it just because you can blow through it. I had the problem you are describing after doing everything I just listed. Then an old Johnson guy told me to replace the filter. He was 100 % correct. I also replaced my coils and points when I started my repairs. The coils are cheap and easy to find. One other thing I did was buy a Timing Fixture I found it on EBay. It makes setting points and timing very easy and you will be dead on when done. If you have anymore questions PM me and I will see if I can help you.