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Wont start in the water

J

jn1440

Contributing Member
Hey everyone got an issue to run by you. Just finished a major overhaul of my 1984 Evinrude 70, new wrist pin on cylinder two, new exhaust plates, new head gasket, the works. Got it all put back together nice and started it up on the muffs in my driveway it ran perfectly no knocks no noise and fired up on the first crank to idle flawlessly. Next step was to head to the boat ramp! Got to the ramp and put it in the water and it wont even try to start just like I had pulled the kill switch. Pull it up the ramp and fires up immediately, put it back in the water and it fires up after a bit of cranking but idles real slow and eventually dies out. Compression is 110 on every cylinder got spark on every cylinder too. I assume all cylinders are firing because when its running on land I go and cover a carb and it starts to choke out with each cylinder. Really stumped on this on would appreciate some input!
 
Figured out the reason it wont run in the water, the middle cylinder is dead. Spark is good, pulled the plug out and watched it spark. Compression is good, 110, that doesn't seem high enough but the other two cylinder are at 110 and they run fine. I guess fuel mix is the issue, however the plug is wet and I don't see anything wrong with the carb when I took it apart. Carbs were rebuilt when the engine was done, new fuel pump and fuel lines as well.
 
Is this engine incorporating a VRO or has it been converted back to a 50/1 fuel mixture usage?

Did you thoroughly clean all the carburetors... including the high speed jet that is located horizontally in the bottom center portion of the float chamber, way in back of the float chamber drain screw/bolt? That jet must be perfectly clean!

Compression of 110 is okay. Spark plugs should be Champion QL77JC4 plugs... keep them gaped at .040 until all is well, then drop the gap down to .030.

With all s/plugs removed, the spark must jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? The stator under the flywheel is the beginning of the ignition system, if there is a sticky looking substance dripping down from it upon the timer base and/or powerhead, replace it as that indicates the stator has failed and this results in a voltage drop to the powerpack capacitor (weak ignition).

You indicate that the engine starts and runs perfect on a flushette BUT will not start when in the water. This relates to the following cranking problem:

(Engine Won't Start or Hard Starting In Water)
(Joe Reeves)

The Evinrude and Johnson engines, starting in 1973, have what is called Magneto Capacitance Discharge ignition, self contained, not dependent on battery voltage. The engine must turn over at least 300 rpms in order for the flywheel magnets rotating past the stator ignition generating coils to supply approximately 300v AC to the powerpack(s), which in turn is needed to supply power to the coils etc etc (spark).


In the water, exhaust back pressure is encountered due to the fact that the exhaust housing (housing between the powerhead and the lower unit) is filled with water. This would drag down the needed rpms, affecting ignition.

Normally the clue to this type problem is that the engine starts fine on a flushette (hose), but is very difficult to start when in the water.


Should this be the case, check the battery, clean and tighten all conections (use a wrench or pliers, not your fingers). Any cable that gets overly warm or hot indicates either a loose, or tight but dirty, or internally corroded cable. And of course check the starter itself.

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
 
There is no VRO just 50/1 mix in the gas. Just went over the electrical system before this, new batteries new cables the works. The starter is very healthy now it will turn the engine over at close to 1000 rpm in and out of the water. I will try a real spark tester as I am not sure how strong the spark is I just know its there by putting the plug against the block and cranking it over. Will pick up some new plugs too, why do you say gap the plugs more? Not questioning you just curious. I think, key word here, that the carbs have been cleaned good I disassembled everything I could then blew it out with crab cleaner and followed up with compressed air then reassembled with new parts cautiously.
 
Noticed something new, I went to test the spark with the spark tester and as the engine was cranking over there was fuel pouring out of the vacuum/breather nipple on the reed plate below the bottom carburetor.
 
Make sure battery is fully charged and spinning fast enough to provide a good spark during start. ALso when its in the water the backpressure will give you a lower idle rpm. Try increasing the idle speed on the muffs
 
Inspect carburetor floats and float valves.--------And do not start this motor up dry with no water to the pump !!
 
The original factory recommended gap was .040 and was revised in the late 1990's somewhere to ,030. The smaller gap supplies longer plug life. The wider gap supplies a hotter spark... it was just a suggestion and may not make any difference.

If that electric starter cranks that engine over 1000 rpm, you got one hellava starter! :cool: I suspect that tachometer is reading wrong.
 
Well maybe not a 1000 haha but it turns it over good. I tested the spark with a gap spark tester at 7/16" and surprise surprise there is no spark on the problem cylinder. Must be a weak spark because it will spark the plug but will not jump the gap like the other plugs. I cleaned the grounds and checked wires for that cylinder and nothing obviously wrong stand out so I assume bad coil? The other issue is all the carbs now refuse to hold onto their gas and just pour it everywhere guess I'm not that good at rebuilding them so I got fresh rebuild kits and will go over them again with a friend who has more experience with carburetors.
 
To test the non firing coil, simply switch the wire of the powerpack "temporarily" that leads to a firing coil with the non firing coil. If the non firing coil now fires, then obviously it is okay... if it does not fire, replace it. Be sure to return the wires to their original positions.

The weak spark... jumps a plug gap but not the 7/16" gap... does indicate a bad coil, but the above test will either back you up or disprove that assumption.

If the coil fires on the above test, that indicates that either the powerpack... OR... the related timer base sensor is faulty. To test those two items... with the coils wired properly to the powerpack, temporarily switch the "colored" timer base wires that lead to the powerpack. If that coil fires, the pack is okay (timer base is faulty). If the coil remains faulty and does not fire, the powerpack is faulty.

As you can see, with a little thought.... the engine supplies its own test equipment.
 
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Did some testing of the coils and it seems like to me that the spark plug wires are the issue. The top coil fires a strong spark and the top coil also has a new spark plug wire, why only that wire was changed I don't know, but the bottom two coils aren't firing at all until I put the wire from the top on them then they started firing.
 
Good news! she is firing on all cylinders now off to the boat ramp to confirm but I am feeling good about it. It was the coil after all, my tests were messed up because the wires were not snapping properly on the coil so with the weight of the spark tester it pulled the wires off enough. Squeezed the ends of the wires so they snap now and redid the coil swap test and the issue stayed with the middle coil. New coil is on and the engine seems to be running well now! Thanks everyone for the help I would still be messing with carbs thinking that was the problem without the help. If you don't hear back from me that means the launch went well.
 
Hello does any buddy know why my Doral splash water craft starts out of the water even starts on the trailer but just in the water enough to blow water out the rear jet but as soon as I put in the water and jump in it just cranks over fast but will not start take out of the water and starts ok but leaving it submerged on the trailer in a about four inches of water and lots of water comes out the rear jet I am stumped yet back it in the water partially submerged leave it running and works fine while I run it inthe lake lots of power believe it is a 1997 Doral splash
 
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