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outboard quits working on the lake

T

tbabs

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I have a Johnson 65 hp outboard (it's on a '73 boat and I beleive the engine is from the same time.) Here's what is going on.
It runs perfect on the flusher in the yard. Starts up instantly. Took it to the lake: Saturday started just fine at the boat access, drove it across the lake, anchored and fished for about an hour, started fine and went somewhere else, sat for and hour or 2 again, and engine would turn over fine but wouldn't start, tried for about 5 mins, let it sit for another 30 mins, tried again, turning over fine just not starting, checked plugs and they are wet, all 3 plugs have spark. eventually dead battery. get it back home, starts right up with the flusher. Sunday same thing, 3rd or 4th time i tried to start it on the lake it started, put it into gear and it died, wouldn't start again. Plugs weren't wet this time, but i wasn't trying it as much. Got it home, it started. Monday just a repeat of Sunday.
 
I believe it only sounds good to you on the hose.---------------Start with a compression test.---------Then do a spark check with the 3 plugs still in the head.---------Spark must jump a gap of 7/16" or more, does it do this , yes or no.
 
I have spark on all 3 plugs, i've checked that, cant check compression right now cause i don't have a tester, but i can check that later
 
Does the spark jump a gap of 7/16" or more with the plugs still in the cylinder head, yes or no?-------This is an important definitive test !
 
Neighbor had a test so just tested it. All 3 plugs do have spark (checked again) and the compression on all 3 was about 102. How do I test the spark plugs are jumping that far? do i need a tool? i've been testing it by taking the plug out and reconnecting it back to the cap, the turning the engine over with the plug grounded on the engine.
 
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Plugs grounded to the engine is NOT a very good test of what this ignition system is capable of !!-------On my compression tester I would expect 140 PSI or more.
 
It wasnt a screw in tester it was just one you hold into place, so might have been a little lower than accurate. is there a way i can test that the spark is ok without a tool?
 
tbabs said:
It wasnt a screw in tester it was just one you hold into place, so might have been a little lower than accurate. is there a way i can test that the spark is ok without a tool?
Click to expand...

(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 
65ESL73R = 1973 65hp Johnson

Switch the non firing coil with one of the firing coils to test the coil.

Let us know what happens.... bad coil, good coil?
 
Next time it won't start, try it using the manual choke (choke on or choke off). Sometimes those things would choke when it wasn't needed. There is a service bulletin on that. However that doesn't explain why no spark on #3. Also, are you giving it some throttle with the fast idle lever? Also, check for water intrusion into the cylinders.
 
Sorry haven't had a chance to mess with the coils yet. Will after work today. Also as far as the manual choke goes, I'be tried it with it on and off and automatic. Tried it with the fast idle up, tried it with full choke. Didn't start. Spent about 4-5 hrs total stranded on the lake between Saturday-Monday so played with all that stuff trying to get it started again. But then every time od get it back home and on the flusher it'd start right up. No choke or idle lever need, just 1 turn and it start. Was frustrating.
 
Ok, sorry about taking so long. Been busy. Tested all 3 plugs again and today all 3 were jumping the 7/16" gap.Even the bottom one. Didn't move the coils or anything.
 
Spark plugs should be Champion QL77JC4 plugs gaped at either .040 (strong spark) or .030 (long life).

If you have compression and proper spark, that leaves fuel. This is due "usually" to a fouled high speed jet located in the bottom center portion of the float chamber... way in back of that drain screw plug (it has 1/4x20 threads), Clean it carefully with a piece of single strand steel wire as solvent just doesn't do that job properly.
 
Yep those are the plugs. I'm not sure whether they're the .040 or .030 though... took the carbs off and cleaned them. They looked pretty clean already, but sprayed them out. Used a wire and some carb cleaner for the jets in the float chamber. I guess from here I'll just have to give it another shot on the lake?
 
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