fuel/ oil mixture help 4w70e

I just bought my first outboard, a 4hp johnson. How important is the fuel/oil mixture? Can it cause the motor to not start? Can it cause harm to the engine? I just found out that I used the wrong mixture.

Instead of a 50:1 mixture ( I think that is the correct ratio for my model) I went by the label on the oil container and put 1 ounce per gallon. there was 2 gallons of gas so I only put in approx 2 ounces instead of 5.12 ounces.

Is it okay to put too much oil in?

Re: fuel/ oil mixture help 4w70e

4W70 is a 1970 model and the recommended fuel mix according to http://www.evinrude.com/en-US/Owners-Center/FAQ/OilAndFuel is 50:1

However it does not have needle roller bearings through out so a somewhat more oily mix may well be advisable. 40:1 perhaps. See also http://forums.iboats.com/showthread.php?t=158072

As thin a mix as 1 ounce per gallon .. thats 128:1 would be very bad for that engine.
As far as I can see there is no separate seal to the lower crankshaft bearing so it relies on the oil film to make a seal in the bearing itself. Lack of that oil film might make it difficult to start.
At least if you have not been able to start it it you have not done any damage due to running with so little oil

A little extra oil will do no harm and I'd expect that engine to run quite happily on 24:1 even ... that would probably have been the recommended mix during the break in period when new.

BUT start your trouble shooting, once you have the correct fuel mix by checking, cleaning, resetting or replacing the plugs ( J6C gapped at 0.030") and checking that you have two good sparks.

As it is anew motor to you check or change the gearcase oil and also consider a new water pump impeller.

See http://forums.iboats.com/showthread.php?t=158086 Although much is more relevant to large motors there are several bits that you should take note of.

Re: fuel/ oil mixture help 4w70e

Vic.S said:

4W70 is a 1970 model and the recommended fuel mix according to http://www.evinrude.com/en-US/Owners-Center/FAQ/OilAndFuel is 50:1

However it does not have needle roller bearings through out so a somewhat more oily mix may well be advisable. 40:1 perhaps. See also http://forums.iboats.com/showthread.php?t=158072

As thin a mix as 1 ounce per gallon .. thats 128:1 would be very bad for that engine.
As far as I can see there is no separate seal to the lower crankshaft bearing so it relies on the oil film to make a seal in the bearing itself. Lack of that oil film might make it difficult to start.
At least if you have not been able to start it it you have not done any damage due to running with so little oil

A little extra oil will do no harm and I'd expect that engine to run quite happily on 24:1 even ... that would probably have been the recommended mix during the break in period when new.

BUT start your trouble shooting, once you have the correct fuel mix by checking, cleaning, resetting or replacing the plugs ( J6C gapped at 0.030") and checking that you have two good sparks.

As it is anew motor to you check or change the gearcase oil and also consider a new water pump impeller.

See http://forums.iboats.com/showthread.php?t=158086 Although much is more relevant to large motors there are several bits that you should take note of.

Click to expand...

Thats the problem. I got it started with the gas oil mixture and the motor didn't run right. It didn't push the boat and just didnt sound right. I eventually turned it off after 10-15 min. After that I havent been able to start it again

Re: fuel/ oil mixture help 4w70e

A compression test would be sensible.

Remove both plugs and pull over 5 or 6 times before reading the gauge.

If low put a little oil in the cylinders and try again.

Check your sparks. Check, clean, reset or replace the plugs as already said.

Try spraying some two stroke mix directly into the carb throat. If it fires and runs briefly it perhaps indicates that the carb requires cleaning.

Re: fuel/ oil mixture help 4w70e

Vic.S said:

A compression test would be sensible.

Remove both plugs and pull over 5 or 6 times before reading the gauge.

If low put a little oil in the cylinders and try again.

Check your sparks. Check, clean, reset or replace the plugs as already said.

Try spraying some two stroke mix directly into the carb throat. If it fires and runs briefly it perhaps indicates that the carb requires cleaning.

Click to expand...

I did a compression test already. Both were around 60-70. I checked the compression 4 times just to be sure and the last time I lost all compression in the engine what do you think?

I already cleaned and rebuilt the carb.

Re: fuel/ oil mixture help 4w70e

redrum12 said:

I did a compression test already. Both were around 60-70. I checked the compression 4 times just to be sure and the last time I lost all compression in the engine what do you think?

I already cleaned and rebuilt the carb.

Click to expand...

60-70 psi is not good but it should run. I do not understand how you got that sort of reading several times but then lost all compression.

Is the gauge Ok?

Re: fuel/ oil mixture help 4w70e

Can you explain yourself a little when you say it wouldn't push the boat. Do you mean the boat would not move at all or would not plane the boat or was it something in between? As far as compression I hope your not doing a leak down compression check. What your looking for is the highest reading you get. Follow Vic's instruction. Best of luck. Rick.