1970 Chrysler 45 HP unburnt fuel from exhaust + no smoke

[Nmocci]

hello, i have a 1970 Chrysler 45 HP outboard. Model # 455HA. I just recently purchased the boat and motor. I've taken it out a couple times. Each time i notice white bubbles coming from the exhaust in the water. They rise up and pop and leave a sheen on the water. I know this is unburnt fuel. It is not gear oil. When i adjust the fuel mixture at idle i can lean it out and make it miss and it will puff these white bubbles out the exhaust. When i pull the boat out of the water it will have some white foam coming out of the weep holes. I replaced the crank seal under the timing plate and it seems to run much better but still has the white bubbles and no smoke from the exhaust. Where it is a 2 stroke i would expect some blue smoke from the exhaust. the couple times I've taken it for a ride it seems to have steam coming from the upper exhaust with the exiting water. its not scorching hot coming out and the head/cylinder is not burning hot to the touch. I have 110 psi in each cylinder. Ive rebuilt the carb, Wondering if anyone has any ideas? Ive been researching and trying different things for a couple weeks now and i figured it was time to ask for help. Any help is appreciated and i thank you in advance for it.

 

[jerryjerry05]

Welcome,
​When you run the sentences together in one long line it's really hard to read??

The fuel recirculation system.
It's located on the side with the fuel pump.
It looks like a dog bone(kinda) it has a reed and maybe a screen.
It could be clogged?
It's supposed to aid in recirculating the unburned fuel.
The gaskets are available but the screens no.
You don't really need them.
The old days the reeds and screen would carbon and shut off the system.
Try cleaning it.

The steam is normal.

The smoke will always be worse the slower you go.
You can try the higher dollar oils like Amsol or the premium oils.
They say less smoke but it's pretty expensive.

 

[Nmocci]

I'll have to go out and take a look. I have the older style fuel pump with the glass globe on the bottom. I wasn't aware these had a recirculation mechanism.

Sorry for making it hard to read. It was hard enough to write!

As for the smoke none comes out of the motor at all. I wasn't sure if this was normal or not.

 

[Nmocci]

The only thing I can see is two tubes coming off the front and routing to the opposite side of the motor as the fuel pump and down to a nipple beside the base of the power head.
On the fuel pump side there is nothing but the pump.

 

[jerryjerry05]

It's there keep looking against the block
http://www.**********/parts/search/M...74G/parts.html
​#43boatsdotnet under the x's

 

[Nmocci]

I don't think the 1970 models are the same as 1974. I do not see anything around the fuel pump.

 

[jerryjerry05]

Can you take a pic of the block?
​You'll need 5 posts to be able to post pics.

 

[Nordin]

The 1970 and 74 models is very very similar to each other.
The recirculationssystem is under the cover where the lever for the gearshift is mounted.

About the unburned fuel, it look like your engine is working as it should. Maybe cleaning the recirc.system will improve.
Most smoke will enter thru the exhaust snort under the water.

BUT remember the engine is 46 years old and in those days the environment and fuel economy was not on focus as today.

 

[Nmocci]

Yes I can take a picture. I didn't think I was missing anything.

Between rebuilding the carb and doing the crank seal it has depleted it quite a bit, but I was hoping to use this for trolling. At an idle it produces much smaller bubbles and at a lesser rate. But they are still there.

I do understand that they weren't so environmentally conscious back in the day. I'm not a tree hugger but I don't want to pollute the lakes.

Was this normal for these motors? I guess I don't want to try to correct something that can't be corrected.

 

[jerryjerry05]

Posting the pic was so I could point out the recirc system.

 

[Nmocci]

No Title

 

[Nordin]

Please, read thru whole of my last post.
The recirculationssystem is under the cover where the lever for the gearshift is mounted.

 

[Nmocci]

I did read that, thank you. He wanted me to post a picture so I found one on Google and posted it.