No spark on 77 140 hp Evinrude 140783S

[mikietoo]

I'm beginning to trouble shoot a no spark condition and the first thing I run into is a question about the starting RPM. I have no rev counter and the tach is not working so is there some way that I can I use the frequency position on my DVOM to measure the engine RPM? I am fairly familiar with the DVOM but have never used the frequency counter and my book does not say much about the use of it.

Also, where is the trigger circuit. I think the stator coils supply pulses over wires marked sensor (1-4) to charge capacitors (1-4) in the power pack that correspond to cylinders (1-4). How do the capacitors know when to discharge into the coil (1-4) and fire the plug (1-4).

Also, what is the firing order?

I don't have a book yet. I'm getting my info from some stuff that I downloaded from CDI. Which book is best? I've not seen a factory service manual. I have seen Selco, Clymer and Cook but don't know which are best. Cook seems pricey at $70. Don't know if it is that much better. I would prefer a factory book if they can be found.

 

[emdsapmgr]

Re: No spark on 77 140 hp Evinrude 140783S

The information from CDI is very useful. I'd only want an original factory service manual to use when working on that engine. Don't bother with a Clymer or Seloc. You can still get one from the original pulisher at: outboardbooks.com. Generally the 4 spark plug coils are pretty reliable-certainly they have not all gone bad at once. That leaves the stator, timer base and the power pack as possible ignition failure culprits. The stator is divided into two sections, the charging side and the ignition side. Separate sections. You'll want to test the cranking stator voltage output for the ignition side. It may be condemned if it puts out less than some specified voltage, (such as 150 v.) The timer base determines timing and usually also has a small volt output also during cranking (such at .03 volts). The power pack drives the coils based on voltage and timing requirements. Generally the power pack is the common failure item-but considering it's expense-best to test all components before buying anything. You'll need a special "peak reading" voltmeter in order correctly measure output voltages. The factory manual has a number of ohms tests which are recommended. Personally, I've had great luck with the output voltages instead.

 

[mikietoo]

Re: No spark on 77 140 hp Evinrude 140783S

I will get the book. But for now, what is the timer base and where is it located?

 

[Daviet]

Re: No spark on 77 140 hp Evinrude 140783S

Look at #53 below.
http://www.ishopmarine.com/ishop/js...CatFilter=BRP&eCatSupFldr=supplier-100-005-EJ

 

[mikietoo]

Re: No spark on 77 140 hp Evinrude 140783S

Also still wondering about using the frequency counter to count revs. Any chance it can be used for that purpose?

 

[Daviet]

Re: No spark on 77 140 hp Evinrude 140783S

I have never heard of doing it so I guess I can't help you out there.

 

[mikietoo]

Re: No spark on 77 140 hp Evinrude 140783S

Thanks to all and especially Daviet for info on book availability. The book has been ordered.

 

[mikietoo]

Re: No spark on 77 140 hp Evinrude 140783S

I borrowed a hand held tach from where my son works. My battery was new but small (600 cca). I was counting marginal cranking rpm (243, 259, 251, etc.) and still no spark. I jumped the new battery with my pickup and cranking rpm jumped up to around 300. Tested for spark. WOW, now I have spark. It starts and runs. So I have concluded that my new battery is too small. I need to get a battery with higher CCA. After this experience, I don't think I would venture too far in this boat without an extra battery.

 

[Daviet]

Re: No spark on 77 140 hp Evinrude 140783S

Glad you found your problem. I don't think you will have to have a second battery, just a good primary battery.

 

[emdsapmgr]

Re: No spark on 77 140 hp Evinrude 140783S

That engine makes it's own power to fire the ignition based on flywheel rotation. Does not rely on the battery for spark. The battery must crank the engine at least 250 rpm's in order for the stator to make enough power to fire the ignition.