no spark after decarb, 1977 Evinrude 140

[cheft]

Engine was running poorly, wouldn't stay running at idle so I decarbed and when I put carbs back on there has been no spark at the plugs ever since. I have checked the Yellow and black wire at the power pack, no change, disconnected yellow wire from stator, no change , doesn't seem to be points under the flywheel unless there under the armature plate . can someone tell me why a carb cleaning would cause no spark. when I tightened the nut on the carb i touched a hot wire and got a small arc, could that have burned something out.inline fuse is good

 

[mrcj001]

Re: no spark after decarb, 1977 Evinrude 140

No fire at all:

1.(Note: If the engine fires with the spark plugs out but not with them installed, the timer base is either weak or the engine is not spinning fast enough. See # 6 and #8.)
2.Disconnect the black yellow kill wire and retest. If the engines now has fire, the kill circuit has a fault-possibly the keyswitch, harness or shift switch.
3.Disconnect the yellow wires from the stator to the rectifier and retest. If the engine fires, replace the rectifier.
4.Check the stator resistance. You should read approximately 500 ohms from the brown wire to the brown/yellow wire.
5.Check the DVA output from the stator. You should have a reading of at least 150V or more from the brown wire to the brown/yellow wire (while connected to the pack).
6.Check the timer bases resistance from the #1 sensor wire to the #3 sensor wire and from the #2 sensor wire to the #4 sensor wire. Reading should be 10-20 ohms on each set.
7.Check the DVA output from the timer base. A reading of at least 0.5V or more from the #1 sensor wire to the #3 sensor wire and from the #2 sensor wire to the #4 sensor wire (while connected to the pack) is needed to fire the pack. If the output is low, you may try to reset the air gap between the timer base sensor and the triggering magnet using a sensor gap gauge or use the following procedure:
A.Loosen the two mounting screws on the sensors and the nuts located in the epoxy on the outside of the heat shield of the timer base.
B.Slide the sensors in toward the crankshaft until the sensor touches the stop boss located at the base of the sensor mounting area. Tighten the mounting screws.
C.Coat the face of the sensors with machinists bluing or equivalent.
D.Install the flywheel according to the service manual and crank the engine over.
E.Remove the flywheel and check to see if the trigging magnet struck the face of the sensors. If it did, back the sensor out approximately 0.005? and repeat steps C, D and E.
F.If the ignition fired, finger tight the nuts on the outside of the heat shield and coat them with RTV.
G.If still no fire, replace the sensor.

7.Check the DVA voltage on each black/white wire to engine ground. You should have a reading of at least 150V or more (while connected to the pack). If the reading is low, disconnect the trigger wires from the pack and recheck the black/white terminals on the pack. If the voltage jumps up to an acceptable reading, the timer base may have a problem in the internal wiring (A thin spot in the insulation on one wire).
8.Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to fire properly.

 

[jtexas]

Re: no spark after decarb, 1977 Evinrude 140

Plug the emergency lanyard back in and try again.

"Decarb" can't be done without the carbs in place -- the motor has to be running ... can you be a bit more descriptive about what maintenance you did?

No spark any cylinder? How did you determine that?

"I have checked the Yellow and black wire " What kind of checking did you do?

your motor has a magneto-driven capacitor discharge ignition, so there's no points.

Can you identify the "hot wire" that arced while working on the carbs? Color maybe? What it's attached to? How you were able to get an arc from it...I mean, you must have touched a terminal end, or else there's missing insulation or something?

The only electrical device I can think of near the carbs is the choke/primer solenoid, and that only has 12v when the choke is activated.

 

[cheft]

Re: no spark after decarb, 1977 Evinrude 140

thanks for replying, the control box doesn't have a kill switch lanyard. does that mean no kill switch at all? I disconnected the yellow and blk wire from the powerpack and cranked engine , no fire to plugs. reattached yellow and blk wire and disconnected 2 yellow wires from stator to rectifier, no spark. unplugged red plug going to starter and jumped from positive battery cable to small terminal on starter and still no fire. I was in the process of cleaning both carbs off the engine and when i was attaching them back on the engine i forgot to undo the positive battery cable and while tightening the right side nuts i touched the hot cable on the starter and got an arc with the wrench. I am using an in line spark plug tester where you plug one end into the spark plug wire and then attach the other end to the plug itself still in the engine and there is a light that is supposed to light up, no light. i tried pulling the plugs one at a time and grounding them to the block and no spark thats why i bought the spark tester, very cheap one. I can't figure out why it was starting every time i turned it over until i took off the carbs and then no fire since then I will try your advice and these next steps is ther any way to measure with a multi-meter or do i need to find a DVA? i'm not smart enough to figure out the schematic for making one that i saw on this forum. thank you both again for the help.

 

[AlTn]

Re: no spark after decarb, 1977 Evinrude 140

shop2.evinrude.com..1977 140..ignition system...shows an inline fuse #27 on the diagram...maybe you got lucky an it's blown

 

[cheft]

Re: no spark after decarb, 1977 Evinrude 140

no such luck on the fuse. checked the resistance on the stator between the yellow and brown and the brown wire, forum said should be about 500ohms, it was 640, then checked the timer base resistance on 1 and 3 sensors and 2 and 4 sensors, should be between 10-20 ohms 1 and 3 was 8 and 2 and 4 showed nothing, no reading at all does this mean the sensors are bad? I haven't been able to get a DVA so i can't check any voltages yet. RPM's seem at least 1000-1200 . Any ideas about the sensors . I readjusted the sensors closer to the crankshaft and now I need to know what to do next, I guess I need to get a DVA to proceed. can someone direct me to how to adapt a multi meter to work as a DVA?

 

[AlTn]

Re: no spark after decarb, 1977 Evinrude 140

cheft...seems like there's an analog dva for ~$40 that's been recommended several times in various post...I bought a dva adapter..CDI...product...for $60 and it plugs into your multimeter allowing you to read voltages coming into and out of your power pack

 

[jtexas]

Re: no spark after decarb, 1977 Evinrude 140

You got an arc from the starter terminal? That's strikes me as very strange...that cable is only hot when the solenoid is actuated, and when that happens, the starter motor spins. That's a mystery. Unless your talkin bout the battery cable where it's connected to solenoid...would've been quite a spark. How that could blow an ignition component...I dunno but electricity can be unpredicable.

For the spark tests, use a tester with an adjustable gap, set it at 7/16" and clip it to the engine block -- this way you can test the ignition system independently of the spark plugs.

yep, to accurately measure "DVA" voltage you either need a "peak-reading" voltmeter or else a DVA for the multimeter.
this one has been recommended by others on the board for power pack testing:
http://www.usatoolwarehouse.com/usatoolwarehouse/ESI-640.html
Because of its low cost, I'm skeptical of its ability to accurately measure very low voltage, like 0.5V (timer base output spec); I haven't seen any comments on that aspect of it.

no factory kill switch on that motor (but you or a prior owner might've added one -- it's pretty easy whenever you get around to it, generic lanyard switch about $10).

On your resistance tests, I believe 640 is "approx 500", and 8 instead of 10-20 might be ok; "no reading" could mean "zero ohms" (no resistance at all), or "0.L" (open circuit). An open circuit fault would be pretty conclusive, but I'm not sure about 0 ohms.

For future reference, that's a 20-amp fuse on the main 12V feed to the keyswitch; if it blows, the starter motor won't spin, choke won't actuate, gauges won't register, etc.

Also, note that "decarb" refers to the process of cleaning carbon deposits out of the cylinders and is unrelated to the carburetors.............

 

[Narojobra]

Re: no spark after decarb, 1977 Evinrude 140

I am subscribing because I have identical symptoms with my 1977 Johnson 75. It was running fine. I hosed out the boat and went to start it later that day. Now its dead, no spark. I've done the same checks as you with no success. We're in the same boat. I will post if I figure it out. I'm suspicious that it is purely coincidence that the power pack is DEAD!