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‘74 evinrude 85hp M#85493-BF

S

Shane86

New member
Back to the drawing board. Replaced the rectifier and confirmed that battery was holding voltage. Already replaced plugs. Fired right up. Ran great for 5 minutes. Then while at full throttle it just died. Would not start back up. Voltage on battery was still fine. Would really like to get this thing figured out in the next few days if you guys can help me out!
 
Are you saying that the engine cranked over okay but the engine wouldn't fire and run (start)?

Is it a case of not having spark?
 
Shane86 said:
No it runs fine for a little bit. Had it full throttle cruising and it just dies. And then won’t start.
Click to expand...

Yes, I know... but that just "round robins" right back to my original question of: "Are you saying that the engine cranked over okay but the engine wouldn't fire and run (start)? Is it a case of not having spark"

To remove any lack of communication..........................

1 - Are you able to crank the engine over, either via a electric starter or the manual starter immediately after it stopped?

2 - In removing the spark plugs and testing for spark... Is there spark at the spark plug boots that will jump a 7/16" air gap?
 
joereeves said:
Yes, I know... but that just "round robins" right back to my original question of: "Are you saying that the engine cranked over okay but the engine wouldn't fire and run (start)? Is it a case of not having spark"

To remove any lack of communication..........................

1 - Are you able to crank the engine over, either via a electric starter or the manual starter immediately after it stopped?

2 - In removing the spark plugs and testing for spark... Is there spark at the spark plug boots that will jump a 7/16" air gap?
Click to expand...
Now I get what you are asking. Yes. After it dies it will crank but not start
 
Shane86 said:
Now I get what you are asking. Yes. After it dies it will crank but not start
Click to expand...

Okay... Got one answer. Now, how about the spark? :)
Remove the spark plugs, test for spark... Is there spark at the spark plug boots that will jump a 7/16" air gap
********************
(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

This can obviously be modified to a 6 or 8 cylinder setup tester.
********************
 
joereeves said:
Okay... Got one answer. Now, how about the spark? :)
Remove the spark plugs, test for spark... Is there spark at the spark plug boots that will jump a 7/16" air gap
********************
(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

This can obviously be modified to a 6 or 8 cylinder setup tester.
********************
Click to expand...
Assuming that I do have the proper spark and it will jump the 7/16” air gap what would be my next step. As of now I’ve only checked my plugs using a multimeter and they are fine. Waiting for some assistance on checking the air gap jump.
 
Shane86 said:
Assuming that I do have the proper spark and it will jump the 7/16” air gap what would be my next step. As of now I’ve only checked my plugs using a multimeter and they are fine. Waiting for some assistance on checking the air gap jump.
Click to expand...

If you have compression, spark, and fuel... the engine should run.... what to do next depends on whether the engine runs, or has weak or no spark.

With all spark plugs removed and the key in the ON position, Removing the black wire that has a stripe running on it (Kill circuit) from the "M" terminal of the ignition switch would be one step. If you have spark, by cranking with the electrical starter, with that wire disconnected BUT no spark with it connected at cranking speed... the ignition switch would be bad, in which case, replace it.

Another step would be to closely inspect the stator under the flywheel to see if a sticky looking substance may be dripping down on the timer-base and powerhead area, and if so... replace the stator as that scenario would result in a AC voltage drop to the powerpack's capacitor.

Let us know what you find, In Detail.... NOT generalities such as this looks good, or that seems okay, etc.
 
Last edited:
joereeves said:
If you have compression, spark, and fuel... the engine should run.... what to do next depends on whether the engine runs, or has weak or no spark.

With all spark plugs removed and the key in the ON position, Removing the black wire that has a stripe running on it (Kill circuit) from the "M" terminal of the ignition switch would be one step. If you have spark, by cranking with the electrical starter, with that wire disconnected BUT no spark with it connected at cranking speed... the ignition switch would be bad, in which case, replace it.

Another step would be to closely inspect the stator under the flywheel to see if a sticky looking substance may be dripping down on the timer-base and powerhead area, and if so... replace the stator as that scenario would result in a AC voltage drop to the powerpack's capacitor.

Let us know what you find, In Detail.... NOT generalities such as this looks good, or that seems okay, etc.
Click to expand...
Ok. Just picked up an in-line spark tester and all 4 plugs have good spark. I guess what is baffling me is that my boat fired right up and runs great for a short period of time. Then while at full throttle is just dies. Will not start back up. Battery and spark plugs are fine. Just replaced rectifier.
 
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