black test water

[dadurling]

I'm trying to revive a 1971 Johnson 4HP, 4W71D. It's finally running, but the plugs are fouling, I can't seem to get the motor to open up past mid-throttle, and my test barrel water is black with oil. I know I need to adjust the carb settings (and have the great instructions posted here), but would running rich cause that much oil to turn the test barrel water black? I should've done a compression test first, but that's also on my list to do.

 

[Daviet]

Re: black test water

If it will run I would put it in the water and adjust the high/low speed jets properly and see if that helps. What oil/fuel ratio are you running?

 

[dadurling]

Re: black test water

48:1 (fuel/oil!)

 

[SolingSailor]

Re: black test water

Confirm both cylinders are firing.
Unburnt fuel/oil will accumulate quickly on the top of the water.

 

[wmconway]

Re: black test water

If you run it in a tank with oil for too long, the oil tends to weaken the bond between the impeller and it's bushing. Clean that tank!

 

[OptsyEagle]

Re: black test water

Check that both cylinders are firing as one of the above posters have indicated. One way to do this, is to start the motor, let it warm up, keep it at a fast idle and with insulated plyers pull off one spark plug boot at a time. The other cylinder should keep the motor running but if it doesn't then the other cylinder probably wasn't working. If the motor will run on either cylinder then you know both were firing. Remember if it is getting fuel but no spark, then that fuel and oil has to go somewhere and that somewhere is your tank. If it is sparking then it will go as exhaust in the air above your tank, not in your tank (however 2 strokes will always leave a little oil/gas residue in the water tank.

The other test that you will eventually need to do is an external spark test and ensure the ignition can jump a 3/8" gap minimum. A compression test would not hurt either.

 

[hidef]

Re: black test water

48:1 is the wrong mix for your engine. You should be 24:1 at a minimum with the preferred being 16:1. That engine doesn't have needle bearings it uses brass bushings. Check your for spark on both cylinders if you don't have it you will need to pull the flywheel and check the points, condenser and coils. Points should be set at .020.

 

[dadurling]

Re: black test water

48:1 is the wrong mix for your engine. You should be 24:1 at a minimum with the preferred being 16:1. That engine doesn't have needle bearings it uses brass bushings..

hidef,
Is that 24:1 fuel ratio due to the age of the motor? The manual says 50:1.

 

[hidef]

Re: black test water

It is not the first time OMC screwed up with oil mixtures. Unfortunately the 4 horse from 1967 to 1978 did not use needle bearings in the bottom end of the engine and or on the conrods. 24:1 will ensure that your engine has enough lubrication to make sure it will last. The recommended plug is a J6 you can go up one heat range to J8 to help reduce plug fouling. The link I supplied has some great info on the older motors although he writes about the 6 and 9.5, 9.9 and 15 when it comes to the ignition system points are points and they are all setup the same way. Also use the parts diagrams to help in dis-assembly and re-re-assembly I find they help a lot.

http://www.sschapterpsa.com/ramblings/OMC/OMC info.htm

http://www.marineengine.com/parts/j...urer=Johnson&section=Cylinder+&+Crankcase

If you haven't changed the water pump impeller you will want to do it. They are cheap and easy to do. When doing the water pump if you pull the drive shaft out of the lower unit you will need to open LU up to put the drive shaft back in as the pinion gear floats on the drive shaft. Make sure you do not lose the key that drives the impeller. This is the ideal time to drain the lower unit and refill it with 80W90 or straight 90W. The only other gotcha on these outboards is the starter spring they are easy to rewind but it can be messy and frustrating I have posted instructions on here for other people.