1964 Johnson 33 fouling top cylinder

Motor sat for 20 years. Before launch yesterday I: Replaced head gasket, points, coils, condensers, water pump, rebuilt carb. Have good spark at each cylinder, 88 pounds of compression in each cylinder. (pull starting) Motor starts, idles OK, then top plug fouls, motor then starts to miss then stalls. Bottom plug shows burning good, top plug is black and oily. Any ideas?

Re: 1964 Johnson 33 fouling top cylinder

Did you actually run it on a boat in the lake? If so, did you try to run it WOT and get the high speed needle adjusted? If idling in a test tank it's not unusual to see black plugs. If "oily" are you sure the cylinder is firing? What plugs are you running and what gap?

Re: 1964 Johnson 33 fouling top cylinder

I did run the motor on the bay today. This morning I couldn't even get the motor to start and idle. So, I took the carb off, cleaned the low and hi speed jets (there was some "varnish" in the bottom of the bowl), reinstalled the carb., and motor started and idled at second pull. So we launched. I ran at WOT, adjusted the hi speed jet for max RPM. We ran great for about 3 minutes, and then the motor died slowly. I checked the plugs, and number 1 and 2 both look OK. I am wondering if the problem is with the cork float in the carb. I rebuilt the carb with new old stock parts which included a (new) cork float. I can't understand why the motor would run great for 5 minute then slowly die and not start. - Maybe the ethanol in the NJ fuel is swelling or dissolving the cork?

Re: 1964 Johnson 33 fouling top cylinder

hey, either you are running too much oil with your gas (probly the case) or your rings might be shot and the oil is getting past the piston. i also use nj gas (i live here) it works fine for me. (my outboards go back to 1949)

Re: 1964 Johnson 33 fouling top cylinder

What shape are the fuel lines in? They may be coming apart from the inside on you and fouling the carb up. Yes, if the cork float is in bad shape it can cause problems.
I do not believe that there is a 1964 33hp Johnson. They were 1965-1970 model years.

Re: 1964 Johnson 33 fouling top cylinder

Yes it is a 1965 RX 13-B (sorry, my mistake - its on a 1964 Whaler we just restored and I was baked by the sun when I posted...). All the fuel lines on the engine were replaced along with the fuel pump. It has a new fuel tank and hose as well. I am running 50:1 oil/gas mix. The main problem now is that, following a carb clean, the engine runs for a few minutes then stalls out, won't fire again unless I use starting fluid, but will only fire and immediately quit at that. Plugs actually cleaned up a bit as we ran at WOT and adjusted the carb. So why would the engine stall, and fail to start - I feel like I am missing something simple? Is there another source of gunk I have not cleaned/replaced yet?

Re: 1964 Johnson 33 fouling top cylinder

Try pumping the primer bulb when it starts to die and see if that helps. Maybe a fuel pump problem. Did you replace with new or rebuild the pump? Also thy loosening the gas cap - tank may not be venting properly.

Re: 1964 Johnson 33 fouling top cylinder

I had replaced with a new fuel pump - it was larger than the original but I am told the original is no longer available. Fit right on with the same size gasket and two machine screws. Boat ran good with it for about 5 minutes. We will try again tomorrow with a different fuel tank (was using a new one but looks like vent does not vent!) and squeezing the primer if it starts to stall.

Re: 1964 Johnson 33 fouling top cylinder

PROBLEM SOLVED. Turns out the High Speed Nozzle was plugged with gunk. I had removed and cleaned the hi and low speed needle valves, but had not removed the nozzel. Once removed, the nozzle has two tiny pin holes that run horizontally thru it that were plugged up solid. Cleaned, reinstalled, motor runs best it ever has. Thanks to all for your help.