Checking the spark - procedure?

[richardbrown67@yahoo.com]

1980 Evinrude 70 hp -- what is the easiest way to check the spark on a motor that has stopped running but will still crank? My motor starts and runs fine, but then after 10 minutes or so of running it boggs down and finally quits. It will still crank but won't run anymore until later. Folks have recommended checking the spark once the motor quits, to determine if the problem is electrical. I own an automotive timing light. Can you give me a step-by-step procedure-for-dummies on how to check the spark on this engine? I'm not a boat mechanic.

Thanks!

Richard

 

[Joe Reeves]

Re: Checking the spark - procedure?

Remove spark plugs. Use a spark tester whereas you can set a 7/16" gap for that model engine. Crank engine and observe spark.

Still no spark?..... Disconnect the large RED electrical plug at the engine. Crank engine by using a small jumper wire from the large battery trminal of the starter solenoid to the small 3/8" nut of the solenoid that energizes the solenoid. If you now have spark with that red plug disconnected but not spark with it connected, replace the ignition switch.

No spark tester? Build the following.

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

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

Let us know what you find.

 

[richardbrown67@yahoo.com]

Re: Checking the spark - procedure?

Thanks for the reply!

Where do I get a spark tester? Are they made specifically for my engine? 70hp 1980 evinrude 3 cyl.

Richard

 

[boobie]

Re: Checking the spark - procedure?

You can make your own as Joe suggested above or go to any parts house and buy an adjustable gap one for around $10.00. Then set it to the gap your OEM manual recommends.

 

[zach103]

Re: Checking the spark - procedure?

can't you just test it like you test any small engine?? Unplug the boot from the plug, remove plug, put the boot back on, hold it against the block. crank the engine and look for the spark to jump from the plug to the block.

 

[Joe Reeves]

Re: Checking the spark - procedure?

Zack.... No, testing spark simply by using the spark plug is a waste of time. The specific gap mentioned for a particular model is important. You can hold the plug wire that approximate specified distance from the block to observe the spark instead of using a spark tester if you wish BUT the spark plug thing is a no no.

 

[boobie]

Re: Checking the spark - procedure?

What you are doing when you use the 7/16" air gap test is simulating what is going on in the cyl when you have compression,fuel, heat and ect. The open air gap test tells you if your ignition system will operate under actual conditions. The old spark plug on the block trick doesn't mean diddley.

 

[tx1961whaler]

Re: Checking the spark - procedure?

Take off your shoes and socks.
Stick your little finger in the spark plug boot.
Have someone crank the motor.
A. Only your hand goes numb = weak spark
B. Your entire arm goes numb = OK spark
C. Your whole body twitches, you heart flutters (or stops) and you pee yourself = GREAT SPARK

Disclaimer: Do not try this yourself. Get your brother-in-law to do it and YOU crank the motor.

 

[jeffersondodson561]

Re: Checking the spark - procedure?

Zack.... No, testing spark simply by using the spark plug is a waste of time. The specific gap mentioned for a particular model is important. You can hold the plug wire that approximate specified distance from the block to observe the spark instead of using a spark tester if you wish BUT the spark plug thing is a no no.

If you the ground (metal part with threads) against the block and check spark this is more than adaquate. If it jumps the proper gap outside in ambient air with no conductive materials (such as fuel) it will definately jump the gap with the proper 14.7:1 air fuel mixture.

 

[Joe Reeves]

Re: Checking the spark - procedure?

Jefferson..... You are in error if you are insuating that my database statement of requiring a certain gap for testing the spark as required by OMC standards is incorrect. The information I inserted previously comes from the former engineering department of OMC and is a standard listing in their factory service manuals. There are other factors associated with ignition spark when compression is applied whereas the strong (7/16") normal spark would still jump across the .030 or .040 plug gap but a weak spark would not.

There was a time when things were done via the shade tree mechanic method but that time has long past us by. The spark plug spark test method would have a tendency to confuse and mislead many boaters into thinking they indeed have proper ignition when they actually do not, resulting in having them travel down a wrong trouble shooting path to waste time and money.

The 7/16" gap mentioned..... On many tests, a weak yellow spark may jump across that gap. This type spark would never jump a spark plug gap of .030 or .040 when in a cylinder under operating conditions, hence the demand for the strong blue lightning like flame mentioned in my reply.

 

[jonesg]

Re: Checking the spark - procedure?

If you the ground (metal part with threads) against the block and check spark this is more than adaquate. If it jumps the proper gap outside in ambient air with no conductive materials (such as fuel) it will definately jump the gap with the proper 14.7:1 air fuel mixture.

Thats what I thought initially but tis not true.
But the proper gap is almost 1/2 inch, you cannot establish that gap with a sparkplug. The reasoning is because under compression the spark has to jump through more air molecules(compressed air). A weak spark will look ok on a sparkplug but fail to spark under compression.
Outboards are persnickety.

 

[Sixmark]

Re: Checking the spark - procedure?

If you the ground (metal part with threads) against the block and check spark this is more than adaquate. If it jumps the proper gap outside in ambient air with no conductive materials (such as fuel) it will definately jump the gap with the proper 14.7:1 air fuel mixture.

There is no way that ambient air conditions should ever be used as a testbed reproduction of an internal combustion engine.

A test light will light up on a weak or strong battery but it won't tell you the voltage now will it!! The same principle applies here.

By using the method that you mention, it only confirms if there is spark or not, it DOES NOT indicate if it is sufficient spark.

 

[jeffersondodson561]

Re: Checking the spark - procedure?

Well it's not like OMC makes any money off of their special tools that they sell. This procedure has not bitten me yet, whereas OMC ignition systems have. I would be interested what a KV meter would say to test that theory. Weak spark on an OMC? No wonder the split fire plugs were such a hit!

 

[richardbrown67@yahoo.com]

Re: Checking the spark - procedure?

Thanks to everyone for chiming in on this thread.

I have ordered an adjustable gap spark tester, so I'll post when I let you know what I find out.

 

[Joe Reeves]

Re: Checking the spark - procedure?

Spitfire plugs? I've searched thru various factory manuals and can find no mention or recommendation of this item.

 

[Sixmark]

Re: Checking the spark - procedure?

Splitfire plugs were a joke designed at robbing people, that's about it. You could accomplish the same thing by cutting a slot in the ground terminal on a standard plug

 

[boobie]

Re: Checking the spark - procedure?

I guess the people who believe in split fire plugs don't believe in factory recommended test procudures either for trouble shooting ignition probs.

 

[jeffersondodson561]

Re: Checking the spark - procedure?

Factory Manuals, come on you know scuttlebutt at the dock trumps Factory Manuals. I have seen my fair share of Split Fire plugs in many a motors, put in by the customer, even heard of them blowing up engines. My only point is how many times have you had to replace L77JC4's do to worn electrodes? Ever seen a Yamaha ingitions systems eat up spark plugs like that? Ever try to see a Yamaha spark on one of those testers? Ever looked closely at the OMC and Yamaha block, to me they seem very similar. All I am saying their is a reason OMC went bankrupt. Yeah now they are a Pheonix a rising (they better be). But I have been to Mercury and Yamaha service schools and the instuctors have asked me "how is BRP going to get their emissions under EPA standards with a two stroke"? I just replied "I dunno they didn't tell me in factory school".

 

[wilde1j]

Re: Checking the spark - procedure?

Factory Manuals, come on you know scuttlebutt at the dock trumps Factory Manuals. I have seen my fair share of Split Fire plugs in many a motors, put in by the customer, even heard of them blowing up engines. My only point is how many times have you had to replace L77JC4's do to worn electrodes? Ever seen a Yamaha ingitions systems eat up spark plugs like that? Ever try to see a Yamaha spark on one of those testers? Ever looked closely at the OMC and Yamaha block, to me they seem very similar. All I am saying their is a reason OMC went bankrupt. Yeah now they are a Pheonix a rising (they better be). But I have been to Mercury and Yamaha service schools and the instuctors have asked me "how is BRP going to get their emissions under EPA standards with a two stroke"? I just replied "I dunno they didn't tell me in factory school".

The simple fact is that BRP's E-Techs, in fact, exceed all EPA emission standards by wide margins. Your instructors were ignorant if they didn't recognize the benefits of direct fuel injection, very lean mixtures and other high tech induction and ignition features. This is not new anymore and the future of outboards is two stroke, not four stroke motors, since the only way four stroke motors will meet future requirements will be with the use of catalytic converters. Of course the new future does not include carbed motors.

 

[jeffersondodson561]

Re: Checking the spark - procedure?

If "Direct Injection" is the answer why did Mercury develop the Verado? And why after all the R&D did the Verado lose one of it's CARB stars? Why did the engineers not go forth with the Optimax? You have to admit that the Orbital Direct injection is better than BIP injectors as far as atomization right? So what makes the Etec meet EPA standards whereas the HPDI and Optimax cannot? Is it because the Homoginized versus Stratosfied injection/ignition at transtioning rpms, because Catalytic converters will be coming in outboards and cats only work at low to midrange rpms. Seriously I don't know what components of the Etec makes it superior in the emissions department?