1979 45hp Chrysler Outboard | Gas Consumption

[MrFishy]

Just got a 1979 45hp Chrysler outboard. Changed out the water pump, oil and put in a new carburetor. Turns right on and idles smoothly but I feel like it uses too much gas. Was thinking of switching out the fuel pump but wanted to see what all you think. The first trip I took it out yesterday used up about 8gallons of gas 50:1 mix in about 2 miles. Is that normal for these old outboards?

 

[Frank Acampora]

At wide open throttle you would expect to use about 5 gallons per hour. How far you get depends upon how fast the boat is going.

 

[MrFishy]

Its using 5 gallons about 30 mins or so at cruising speeds. What would be some good trouble shooting tips? Going to switch out the fuel pump this week. Its also pushing out a foamy gas and oil mixture through a small hole in the lower unit. Thanks in advance for your help...

 

[jerryjerry05]

That motor shouldn't be using that much.
Check the fuel diaphragm for holes.
The foamy mix shouldn't be there either.
Pics??

 

[Frank Acampora]

The float needle may be worn or the float level may be too high allowing the engine to run very rich. Excess fuel will be dumped down the leg into the water.

 

[MrFishy]

No Title

Where do I find the float needle or the float level. Its definitely running into the water as I see the oil popping up. I just got a manual in the mail today and Im excited to get to the bottom of this!

 

[Frank Acampora]

The float or inlet needle and seat is inside the carburetor. So is the float itself. Remove the carb and remove the aluminum bowl. Check for any junk that may be causing the float to hang up. Invert the carb and blow through the inlet fitting. With the carb inverted the weight of the float should seal the inlet needle against pressure. If you can blow through it at all, then the needle or seat is bad. To remove the needle and seat, you must drive out the float pin. the needle will either be rubber tipped or solid. If it is rubber tipped, check the rubber point. It should not be deformed or cracked. If it is a solid needle the rubber seat is in the screw-in brass seat. Some carbs have a press in seat.

The float is set with the carb inverted. It should be parallel to the carb casting with the needle and seat installed.

SO: 691 cc. That means you are located outside the USA, bought the engine second hand from a foreign country, or brought the engine here with you.

 

[MrFishy]

I ordered the manual and Im starting to learn how it all comes together. There was a screw on the top section of the carburator that I tightened it started to use less gas but its still leaking out of the hole in the lower unit. I purchased a rebuilt carb of ebay for 100 bucks but it still has the same issue. Going to try the trouble shooting techniques listed above. By any chance is there a number I can call you on to ask a few questions while getting it done?

Im the third owner of this rig. The first owner took very good care of it the second owner had no idea what he was doing and Im acting like I know what Im doing lol! Im located in Los Angeles Ca. I must say for the age of this motor it lights right up every time.

 

[Frank Acampora]

The brass screw on top of the carb is the low speed mixture adjusting needle. Turning it in too far will cause major engine damage. It should be about 1 turn out from lightly seated. The only thing saving it now is the fact that it is running so rich.

 

[DonegalDave]

it is almost certainly leaking fuel from somewhere. Either internally or externally. Have a good look around the engine with it running and the hood off. If fuel is leaking from the pump or any pipes it will end up going out the drain hole in the lower cowling. if it id dry there then the carb is suspect. A second carb doing the same thing is odd.
As Frank says, randomly adjusting the carb without the manual / experience can lead to big problems.

As with most things, go back to basics and trace the fuel line from the tank to the carb checking everything. Then adjust the carb (from the manual) and see what happens.

 

[MrFishy]

ok - so i will turn the brass key 1 turn out from lightly seated.

I checked there so no fuel leaking from the top it must be internally. Ya i thought by getting another carb I should be set. I also got a fuel pump to replace the old one. Could that be the solution? When I tighten the cap on the gas tank it tends to use less gas as well but thats because it sucks in the gas tank but Im thinking if the fuel pump might have something to do with it. :watermelon:

Why cant everything just workkkkkk properly!!!!!! I do enjoy fixing things tho makes me feel like a mountain man!

 

[DonegalDave]

I also like the buzz of fixing things. But I take a slightly different view. Your engine is working exactly the way it is set up. Just not the way you want it to. It is sucking in more fuel than it should for a reason. If it collapses the tank then the pump is fine.
The float needle that was mentioned earlier (by Frank I think) stops the fuel from pumping into the carb when it has enough in the reservoir. If this doesn't work then it is like a toilet cistern constantly filling and the excess going down the pan.

The problem is then, as mentioned, a poor seal between the valve needle and its seat.
This is easy enough to check, a bit fiddly, but very doable, to fix.

As you now have a spare carb work on getting that one sorted.

Drain any fuel out of the carb.

Identify the fuel inlet and put some fuel pipe on it and secure with a proper hose clip to ensure a good seal. Turn the carb upside down and blow through the pipe. You should not be able to.

I feel obliged to point out that Frank did say all this earlier. If you ignore his. Or anyone else's advise, they quite rightly won't offer any more.

If you can blow through the pipe then post a pic of it here and someone will talk you through replacing the needle / seat.

 

[Nordin]

Check the diaphram in the fuelpump.
If it is worn and has a hole or many small holes the fuel will suck direct in to the crankcase/cylinder and then out in the leg.

 

[MrFishy]

No Title

Just wanted to thank all of you for your help. Special thanks to Nordin. I just opened up the fuel pump and saw this 2 huge tears in the diaphragm. Lucky i had an extra fuel pump that i purchased and just replaced it. Will be hitting the wall in an hour to fish and will post the results.