Electrical testing questions

[RookieinMass]

I am learning how to test and repair my 1986 140 hp Johnson but all I have is the Seloc manual as a teacher and I don't know how much I trust it. I have a good auto ranging DMM and a DVA adapter but I need some help with actually using them. I have replaced the power pack, coils plugs and wires but I now seem to have an intermittant spark problem on one cylinder.

Should the engine be running or cranking when testing?

How do I check the colored wires to white when they are located under the flywheel?

Why does my manual say I have 2 power packs when I only have one?

 

[HighTrim]

Re: Electrical testing questions

As you have found, those Selocs are not good for much other than collection oil drips while you work on your outboard They cover multi year/mult model engines. Get yourself a factory OEM Service manual, it will pay for itself many times over, trust me.


What is it that you are attempting to test?

The following is from the CDI Troubleshooting Guide.

NO SPARK OR INTERMITTENT ON ONE OR MORE CYLINDERS:

1. Check the trigger resistance and DVA output as given below:

Wire Color: Check to Wire Color: Resistance: DVA Reading
White wire: Purple: 35-55: 0.6V or more Connected
White wire: Blue wire: 35-55: 0.6V or more Connected
White wire: Green wire: 35-55: 0.6V or more Connected
White wire: Pink: 35-55: 0.6V or more Connected

2. Disconnect the white/black temperature wire and retest. If all cylinders now fire, replace the timer base.

3. Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack.

 

[RookieinMass]

Re: Electrical testing questions

I hate sounding so stupid but I actually need to know how to do the testing. How and where to hook up my meter, whether anything should be diconnected etc.

I can locate pretty much all the wiring and what it is for. Since it looks like the internal harness is original 1986 I am going to replace it because I have problems with the overheat alarm sounding and now no trim/tilt.

If I also need to replace the trigger I would prefer to do it all at the same time.

 

[HighTrim]

Re: Electrical testing questions

If you are having an intermittent spark problem on one cylinder, start by cleaning up/filing the ground connection then re tighten. If the spark is not jumping as it should, you solved your problem. If it is still intermittent, try swapping the coil/lead with a coil/lead from a known good cylinder. If the problem follows the coil, replace it. That is the easiest way to test without the meter. If it doesnt follow the coil, let us know and we can go from there.

Now, regarding the overheat alarm, what is the issue at hand? Is it sounding, yet you are not overheating? If so, you will need to check the temp switch, although that is usually the likely cause. If it is sounding, and in fact overheating, you will need to service the water pump and/or thermostats and/or water circulation system.

In reference to the trim and tilt, is the system completely not functioning? Can you hear the trim motor trying to run, yet still no movement, or is it not making any sounds at all?

 

[RookieinMass]

Re: Electrical testing questions

Chris,

Let me start at the beginning. On warmup the engine "Coughs" about every 5 seconds. Down river at slow speed she still coughs occasionally. Ran up to WOT, running about 5500 rpm, drops to about 4200 rpm and fluctuates for about 5 mins of high speed running. Finally settles at 5500 but need to slow down then overheat alarm went off. Pulled cover and could touch heads so not too hot. Allowed 1 hour for cool down, restarted with alarm still going off, back upriver with alarm sounding and engine either at 4200 or 5500 rpm.

Seems that I am missing on one cylinder but not sure best way to determine which cylinder. Need to run the test with the DVA . I tried clipping onto the wires but didn't get any readings. Do I need to disconnect the plug and use jumper wires for the test?

The engine temp seems fine so I think the thermostats are okay, where is the temperature sensor?

I appreciate any help you can give me.

 

[F_R]

Re: Electrical testing questions

That coughing or sneezing at idle is caused by being too lean (fuel/air ratio). It is normal for them to want to lean sneeze till it warms up. If it still sneezes at idle when warmed up, check for a carburetor problem, or link & sync problem.

 

[jonesg]

Re: Electrical testing questions

I am learning how to test and repair my 1986 140 hp Johnson but all I have is the Seloc manual as a teacher and I don't know how much I trust it. I have a good auto ranging DMM and a DVA adapter but I need some help with actually using them. I have replaced the power pack, coils plugs and wires but I now seem to have an intermittant spark problem on one cylinder.

Should the engine be running or cranking when testing?

How do I check the colored wires to white when they are located under the flywheel?

Why does my manual say I have 2 power packs when I only have one?

another mass rookie here,
the factory manual tells when to test and how,
ignition off,
ignition on engine not running
and engine running tests.

I fixed a non sparker last week by removing coils and spraying grounds with electronic cleaner, swapped coils around and it sparks. Its worth a try, costs nothin, tastes better.

 

[emdsapmgr]

Re: Electrical testing questions

Get an original manual from the original printer, in Milwaukee, Wisc. Ken Cook Co, 414-466-6060. Give them your model # and a credit card and they will ship you one. The factory troubleshooting information is detailed and thorough. You can take a timing light and check each of the plug wires to determine which is not firing. Once you know which is the faulty one, switch two coils and see if the problem moves to the other plug wire. If not, you will need to look closely at the timer base, stator and pack. A special "peak reading" voltmeter will be required to troubleshoot these electrical compents properly. Electrical problems tend to be heat-related and typically show up when the engine reaches normal operating temperature.

 

[RookieinMass]

Re: Electrical testing questions

Okay.

Just ordered a gap tester and an inductive timing light to help with the diagnosing. I do have an OEM service manual for the 1985 140hp engine, is it close enough to the 86 model to use?

If I pull the flywheel to replace the trigger will I need to redo the timing and a link and sync after reinstallation?

 

[blue_streak]

Re: Electrical testing questions

one way to check which cylinder/plug, if any, is missing is to pull the wire off of the spark plugs one at a time while it is idling. if there is no change in the motor speed, then that is the bad cylinder/plug/coil.

 

[jwbmarine]

Re: Electrical testing questions

I do agree on the 'other' manuals'.....they are good for the absolute basic 'theory' of how they wk....................
there are many sources nowdays,where u can get a FACTORY,service manual,..the same manual;,...that we service refer to in professional boat repair shops........do whatever it takes,to obtain,the manual for the customer's specific engine,....u would be very glad u did..

 

[RookieinMass]

Re: Electrical testing questions

Thanks for all the responses, I'm trying all of them. I ran the 1st test HighTrim suggested and got 42 Ohms for resistance and 3.3 to 4.3 volts on the DVA test. This weekend I'll do a spark test and a timing light test in addition to cleaning contacts with electrical cleaner.

My tilt/trim started working last weekend out of the blue so I am sure that there is an issue with the splices in the wiring harness. Time for a new internal harness.

 

[ezeke]

Re: Electrical testing questions

Pulling the plug wires one at a time on a crossflow may be ok and I personally never had a problem, but as I learned the hard way on my looper, it is a great way to keep the powerpack manufacturer happy.

Try using an inductive timing light or inductive tachometer instead; in the long run it is cheaper.

 

[RookieinMass]

Re: Electrical testing questions

I finally did the spark test this weekend. Set to 7/16" I had three cylinders juming with a yellow spark and one jumping with a white/blue spark. The white/blue spark was on the one cylinder that I thought was giving me problems but on other posts I've read that all cylinders should be jumping with a blue spark.

Powerpack, coils and wires are all new so I don't know why my results seem to be backwards.

I also cleaned the grounds on the coils.

 

[karlow1]

Re: Electrical testing questions

Two things:
To operate on one cylinder, I use an external plug that is grouned by cliping it to one the installed plugs. It has a big clip attached to it with a small hose clamp. Never operate the ignition system with a plug wire open circut. Aso do not use the case for a ground, it might be plastic like mine.
The meter needs to be a peak reading DVM. It needs to be able to read peak DC voltage at about 400Hz about 300Vdc. Most DVM do not have that feature. I did this test last week and had to bring may DVM home from work (Tektronix DMM916). Insert paper clips into the power pack connector to make the electrical connections.

Happy hunting

KP

 

[ezeke]

Re: Electrical testing questions

Were you testing spark with all of the spark plugs removed? It is necessary.

 

[RookieinMass]

Re: Electrical testing questions

No. Why does it make a difference?

I was testing with one pulled for the test and the other three still screwed in. A couple of times the engine started and ran briefly on three cylinders.

Can you point me to someone who would have an internal wiring harness in stock. The link here in IBoats shows out of stock.

 

[karlow1]

Re: Electrical testing questions

Not realy. I that test as well as well. (Checking the full trottle advance)
Pull the plugs, attach them to the plug wires, and position them so that they are in contact with the engine bock. Crank away, the plugs fire away. Just make sure they are not locted near the plug hole in the heads or things might get a little hot! If you allow the ignition to operate w/o plugs, all of the voltages will be excessive on the primary and the secondary of the coils. That is how you break things.
Trust me on this one, or eventually it will cost you with blown coils, or power packs. You see if the ignition fires with a plug attached, the plug will limit the voltage to 15-50KV. The system was designed to operate with 15-50KV. If you oprate the ignition w/o a plug, the coil might put out over 100KV. The wire, and coil are not designed for this high a voltage. The fly-back voltage on the primary will also be proportionaly higher and can pop or damage a switch. It can also cause an internal breakdown in the coil (autoformer).

Now you know.

 

[ezeke]

Re: Electrical testing questions

The spark test of the ignition system is tested with all of the plugs removed to remove the load so that a realistic test of the ignition system can be done without the engine actually running.

If you do a spark test with the plugs in, you are actually trying to check spark at less than half the speed that the engine runs at idle, thus the test is close to useless.

To give anything like a reasonable test of the ignition spark, you need either a running engine and a tester that will connect between one plug and the ignition coil, or, a tester for a non-running engine that has gaps of at least 7/16" for all of the holes and all of the plugs removed. Anything else is just a waste of time. You can make a tester with things as simple as a board and nails, but you still have to have the plugs out unless the engine is actually running.