Johnson 74 15hp starting without plugs?

[jcd]

Need help! Bought boat w/motor this spring, lruns choppy, replaced coil, key way, plugs, etc., but won't stay started the second I ground the bottom spark plug. runs like a charm with no wires connected? takes 45-60 minutes to start once out in lake. tried the kill switch too. what else could there be? baffled!!

 

[Walter]

Re: Johnson 74 15hp starting without plugs?

Wwwhat??? Are you saying this engine runs like a charm with no plug wires attached? Hmmm... now that's something I've never come across before. Somehow I think I'm missing something here.<br /><br />By "grounding" the plug wire...do you mean you're actually attempting to run the engine with a plug wire connected to the engine block? If so, then I wouldn't expect it to run very well...like not at all!<br /><br />When you say it takes 45 - 60 minutes to start when on the lake...what's going on during that time? Is is just sitting...or are you cranking on her the whole time? Wow...that would get old in a hurry!<br /><br />You haven't provided enough info for me to determine whether your problem is fuel or spark. As simple as it sounds...that's what you need to do...make that determination first, then go from there. Good luck! Walt

 

[jcd]

Re: Johnson 74 15hp starting without plugs?

will not run with wire attached to spark plug, like it is grounding out, but as soon as you disconnect metal from metal and just hang rubber on end of spark plug, runs perfect.

 

[JB]

Re: Johnson 74 15hp starting without plugs?

Hey, JCD. If I understand your description correctly, I think you've got a bad spark plug. Switch it with the other one and see if your symptom moves with it. There is a type of plug failure in which the plug leaks so bad it wont arc UNLESS it has an extremely fast rising pulse. When you back the metal connector off you are getting arcing to the plug, which produces the fast rising pulse at the plug electrodes, then it sparks.<br /><br />Double check that you have the correct plugs, correctly gapped.<br /><br />One thing many people overlook is that most electrical devices should not be replaced unless they fail. This does not include plugs and points, because they suffer wear, but it does go for coils, condensers, semiconductors (transistors, SCR's, etc.). The reason is that these devices are more likely to fail in their first hour or two of operation than the next hundred. The reason I point this out is that if the above doesn't correct your problem, it is probably in one of your new parts.<br /><br />Red sky at night. . . . <br />JB

 

[jcd]

Re: Johnson 74 15hp starting without plugs?

Correction, 74 Evinrude 15 hp before electronic ignitions, double points under the fly wheel, checked all wires, will not run with plug wires on spark plugs but take spark plug wires off and hang on end, it will run. changed plugs and same problem, put old plugs back in and still had same problem. could the coils be bad??? could it be the stator under the fly wheel? like I said, will not run with plug wires completely on but as soon as disconnect and hang on end of plug or insert screw driver into end of plug wire and hold away from plug arcs across and runs. the further away I pull, the faster it runs. Any suggestions???

 

[jcd]

Re: Johnson 74 15hp starting without plugs?

Also took plug out hooked it to the plug wire when it was hanging loose there would be spark but as soon as grounded against motor, no spark. took all wires apart from points to the coil, checked the wire goes to the kill switch, disconnected them, and still the same.

 

[JB]

Re: Johnson 74 15hp starting without plugs?

Hmm. This happens with both plugs. It is clearly a poor rise time problem. Did you replace the condensers when you replaced the coils (you said coil before, did you mean coils?) You may have gotten sold the wrong coil(s) for the magneto ignition. A coil for CD ignition would have a very different turns ratio.<br /><br />What correction did you mean? You said '74 15hp the first time. My comments including transistors and SCRs etc. were general, not specific to your engine.<br /><br />Because your engine ran, if not very well, before you replaced parts in the magneto system it seems likely that something you changed is causing the new trouble. Likely candidates are coils and/or condensers that were substituted for the correct parts.<br /><br />Good luck, and keep us posted on any new info you develop.<br /><br />Red sky at night. . . <br />JB

 

[Walter]

Re: Johnson 74 15hp starting without plugs?

Hey JCD...<br /><br />If you're like me, ya never throw anything away. You still got the old parts you replaced? Put them back on and see if your engine runs as it did before. Now that I more clearly understand your situation, I'm with JB and wonder if the new parts you installed are creating a new problem. Just so I got it straight...it ran ok (well sorta)with the plug wires properly installed BEFORE you changed coil, etc... It was only after you put on these new parts that it wouldn't run with the plug wires connected? Is that correct?<br /><br />Walt