1967 6hp Johnson. Timing problem?

[gavin dunne]

Hi. I have a 1967 6hp Johnson, which I am trying to revive after 20years of lying up. I had one spark on top cylinder and would run for 1-2 seconds when some fuel was squirted into the cylinder before I touched it. I have now replaced the coils, points and condensers, also rebuilt the carb, replaced plugs and the impeller. Fuel pump checks out for no leaks. I have two sparks now and fuel getting to the carb but it still won’t start. I have read thru the faqs but don’t know how to progress. Any ideas?. The carb seemed clean as a whistle before cleaning and I didn’t notice anything on the reeds although I don’t know what they should normally look like. One thing which worries me is that when installing the armature plate I noticed that the ring on top of the crank shaft to which the plate is attached by 4 screws can rotate freely around the crank shaft. Is this normal? I would have thought that the armature plate position with respect to the cam would be critical and that if the plate was free to rotate then the timing of the points with respect to the piston stroke could be out. Am I worrying about nothing? Thanks in advance

 

[Paul Moir]

Re: 1967 6hp Johnson. Timing problem?

The armature plate is supposed to rotate as you advance the throttle. This allows the timing to advance as the RPMS increase. Since combustion occures at a given rate, on all gas engines you must initiate combustion earlier and earlier in the cycle as RPMS increase so that maximum pressure is developed when the piston has reached it's downward stroke.<br /><br />Is the armature plate rotating with the throttle or is it free? Is the cam on it activating the roller follower that open's the carb's butterfly? Those two things will need to be timed together, known as a link & sync.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

The armature plate is rotating with the throttle and the cam follower on the carb is opening as the plate rotates. I have sync'ed the carb with the ignition as per the manual. Seems I was worrying about nothing then. Thanks for putting that to rest. I still can't get the engine to start though.

 

[Paul Moir]

Re: 1967 6hp Johnson. Timing problem?

Start with the basics - compression, fuel, spark. Check to see if you have good spark. If it jumps a 3/8" gap on each cylinder you can be confident that the ignition system is healthy and the points are set at least close to correctly. Check at a couple different throttle positions just in case there's something wonky going on.<br />Put a little pre-mix in a spray bottle and spray some down the carb's throat. See if you can get it to fire on that. That will bypass the entire fuel system. <br />Make sure you don't have your spark plug wires the wrong way around. Front/Starboard coil drives the top cylinder.<br />It sounds like you've done some extensive work on this engine. Did you make up any of your own gaskets? Which?<br /><br />Reeds are likely not a problem, especially if you looked at them and didn't notice anything really obvious like one missing. They are almost never a problem on J/E engines; if they're there and not bent, they work.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

Thanks for your input Paul. Having somebody to bounce ideas/questions off is great. Spark seems healthy to me. Compression is unknown. I'll have to source a gauge. I know both cylinders should have similar compression but what sort of pressure should they hit? I have been considering the fuel. As I mentioned I can get fuel out of the pump to the carb. But how do I check is it getting from the carb to the cylinders? The plugs don't appear to be wet after cranking for a while. Shouldn't a drop of fuel be visible on the electrode. I've tried the throttle in different positions but still no luck. I'll try some fuel in the carb throat next. The plug wires aren't mixed up and anyway it doesn't start when they're switched. As for the gaskets all work was the carb was rebuilt with a sierra carb kit, I didn't change the gasket on the pump as I was just checking it not replacing it. Should I have?

 

[CATransplant]

Re: 1967 6hp Johnson. Timing problem?

I'd try a spray of fuel into the carb throat. You don't need a lot. If the thing fires when you do that (it'll run for just a second), then you have a fuel delivery problem. Could be many things, but since you said the fuel is getting from the pump to the carb, I'd start with the float level. If it's grossly misadjusted that could be it.<br /><br />If you've been cranking this for a long time, using the choke, etc., the plug electrodes should be damp if there's fuel going through the carb.<br /><br />The spray test will tell you. Use normal fuel/oil mix.

 

[Paul Moir]

Re: 1967 6hp Johnson. Timing problem?

The bit about the gaskets is a really remote problem, but one that's happened to a couple people here who have made their own. These people shall remain nameless, but neither are unfamiliar with outboard repair. Anyway, somehow the exhaust gas hole on a powerhead base gasket never got cut out or the gasket got flipped so the exhaust was completely blocked off. Therefore no fuel/air ever entered the cylinders. I suppose it would be possible to do the same with the carb mount gasket. <br /><br />Follow CATransplant's advice. It sure sounds like a fuel delivery problem to me. The gasket on the pump rarely needs to be changed; I wouldn't think twice about it.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

I squirted some fuel mix into the carb throat and she started on 3rd pull. It dies after about a minute but seems to keep going longer if I keep pumping with the squeeze bulb (haven't had much more than about 5 minutes to work on it over the last couple of days). I guess the fuel pump might be faulty afterall. Could be I have a air leak at the fuel intake of the carb, hose clip seems a little loose. Thanks for all the advice.

 

[Paul Moir]

Re: 1967 6hp Johnson. Timing problem?

Absolutely. If the inlet line to the fuel pump has an air leak in it anywhere it'll draw in air instead of fuel. It'll cause the symptoms you're describing.<br /><br />The o-ring in the connector is replaceable, but if the clip is a cheap aftermarket one just replace the whole clip. If you want to be sure about the problem, you can temporarily replace the line from the fuel pump to the carb with a transparent one and look for bubbles.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

Paul/CAT I can't thank you enough for all your advice. Hopefully I'll have this thing running soon. It was my fathers and hasn't been run in over 20 years so he and I would get a real kick from getting it going again.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

I replaced the line from pump to carb with a transparent one, clipped on tight. No leaks there. Running a bit better but still inclined to stall after a few minutes. I can now see the fuel going to the carb though. Sometimes the line is completely full of fuel but sometimes it nearly empties before more fuel is delivered by the pump. Also the motor tends to increase revs for no apparent reason. Thinking that these symptoms indicate that the pump is faulty.The pump delivers a steady drip-drip when cranking with the fuel line off. It this enough? I've also rechecked the carb for blocked orifices. Confirmed that all are clear except for two passages which run from near the throat of the carb to meet at the low speed needle. There is a little silver disc above the point that all three meet but I can't get this disc out. If I squirted some Power Tune down these passages would that clean them? Would I have to take off the carb again to do this to prevent damaging rubber/plastic internal parts?

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

CAT you mentioned float misadjustment did you mean that if the float closed the fuel inlet too soon the fuel level in th bowl will be too low to allow it to be sucked up into the venturi?

 

[mikeyzx2]

Re: 1967 6hp Johnson. Timing problem?

The disc you're describing is called a welch plug or core plug. I typically take a small drill and carefully drill a small hole then thread a screw onto it and pry it out. The plugs come in carb kits. To install insert the plug with rounded side out then use a small rounded end punch big enough to flatten it out but not puncture it. I used some red sealant from mechanic's shop to seal it.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

Mikey<br />I had considered doing just that but was worried about damaging something under the plug. Just what is under it?

 

[Paul Moir]

Re: 1967 6hp Johnson. Timing problem?

Just under it is a cavity with a one or two precision drilled holes into the throat of the carb. There's a little more than 1/8" of space beyond the the plug so just as long as you drill slowly & carefully you won't do any damage. Some techs use a sharp awl and punch right through the disc with it, and then pry it out.<br /><br />But you should never be seeing any air in the fuel line to the carb after you initially prime it. Either the pump is sucking air or air is getting into the pump through it's diaphragm. It's very easy to test the pump. Simply unscrew the two screws that attach it to the engine, and pump the primer bulb. If any fuel comes out the little hole on the back of the carb, then the pump is faulty.<br /><br />If that checks out, the next thing to do is repair the quick connect fuel line fitting. The o-ring in it wears out pretty quickly and it's often the culprit. Either that or the connection at the tank, a leaky fitting somewhere, etc. You'll need to do a little detective work.

 

[gavin dunne]

Re: 1967 6hp Johnson. Timing problem?

Just to give an update on the final outcome of this. The fuel pump checked out ok. I replaced the primer bulb on the fuel line as the check valve was shot. Runs fine now. Strange thing is that the shot primer bulb worked fine with my Mariner 30hp. Maybe the fuel pump is just a bit stronger on the Mariner.<br /><br />Thanks for all the help.