Load resistor - how used

[OldPcGuy]

I'm off to Rat Shack for a 10ohm 10watt resistor... to use as a "load resistor". Is this the part I need for DVA testing on a 1987 200hp evinrude..??

Do I use the resistor to "replace" the coil in the circuit , and test... from the PwrPck "side" of the resistor..??

(Waiting for my OEM manual)

 

[boobie]

Re: Load resistor - how used

If your getting an OEM factory service manual you may not need it. If I remember right they started using the resistor in 1988 when QS and SLOW came out. If I'm wrong I'm sure I will be corrected. The service manuals called it a pl-88.

 

[daselbee]

Re: Load resistor - how used

That's a waste of time. Just do the orange wires to ground voltage test. You should see around 200 v.
You must use a DVA meter or a DVA adapter on your existing meter.

 

[boobie]

Re: Load resistor - how used

If it's a waste of time, why did the later manuals call for using it?? By the way, the orange wire was for the center cyl and blue and green went to top and bottom.

 

[daselbee]

Re: Load resistor - how used

Waste of time because you will not learn anything new that the voltage measurements from the orange wires will tell you.
Proper voltage there will tell you if you got a hot stator, no voltage there can point to various other things.

Orange/blue is top cyl., orange is middle cyl, and orange/green is bottom cyl...I didn't think they changed anything from 1987 thru 2001 regarding the ignition color code. Did they?

 

[metriccrescentwrench]

Re: Load resistor - how used

If you have the proper adapter you can measure the primary voltage going to the coils. If you don't have the proper adapter the manual says you can use the 10 Ohm resister instead, to simulate the load a coil puts on the power pack. One side of resistor goes to the primary (orange; orange/blue; orange/green) wire and the other side to ground, and you measure peak voltage between ground and the hot side of the resistor.

Either method will give pretty much the same results. You've got to have a proper load on the power pack to get a meaningful measurement, that's why you need to use either an adapter on the coil or else the resistor.

 

[OldPcGuy]

Re: Load resistor - how used

Ok... so with the orange wire connected to the coil, and measuring from the orange wire to ground... at idle it seems I'm getting less than 200 volts... and with more RPMs.. the voltage goes up, but it doesn't 'look' like it gets to 200 to me.

Sorry for my ignorance (I know plenty, plenty enough to get into trouble.!!)

But, I set the meter to DCV (DC Voltage?) and first put it on 1000 range... then on 200 range... and I got readings like 10.3 or 12.5 ... never even a 20.0... The meter setting obviously 'moves' the decimal place, but...

Unfortunately, I didn't get to do a 'full' test... one Grandson crashed his bike, then dinner was served... then it was dark. So first thing Fri morn, I'll measure all cylinders...

FWIW, CDI test procedures say... (for motors 1979-88, no QS), to test orange wire with coil, and if test is 'low' test with "load resistor"... if test remains low, bad PwrPck or TimerBase... if test is 'good', bad coil.

Now, from some of what I'm "learning" here... (thanks to all for so much helpfull info..!!) I'm about to find a timing light, and get a spark "gap" tester... and check the "strength" of the spark... Then check to see if I'm getting an "intermittent" spark... and try some of these DVA tests...

Hopefully I'll eventually identify a culprit (among many possible/probable) to get 'fixed'.

Thanks again to all who give such helpful advice... much appreciated.

 

[daselbee]

Re: Load resistor - how used

Well...that 200v value is not fixed in concrete. If the stator is hot, it will put out a voltage that high....If it is 175v I would call it Ok...even down as low as 150 or so.....

Look, I am just practical. I don't want to do more than I need to in order to fix a broken engine. I am sorry, but I did not read thru the whole thread, so I do not know what problem you are fighting. BUT, if you have 175 DVA volts at all coils (for example), I find it very unlikely that this would be causing ANY problem. For example...assume engine is rough....missing...you see 175 DVA volts at the coil primaries....assume that the book says 185 or more....COME ON....10 volts difference in the ignition system at that point will not cause the problem.

Look at is from a practical viewpoint. If you go ahead and use the load resistor, please post back what you find using it, vs. using just the coils as loads.....

Just trying to help.

 

[metriccrescentwrench]

Re: Load resistor - how used

at idle it seems I'm getting less than 200 volts... and with more RPMs.. the voltage goes up, but it doesn't 'look' like it gets to 200 to me.

Are those values using a DVA adapter? (You never explicitly said you were using one, just asking.) You absolutely have to use that to get meaningful numbers, and from your description of the readings it sounds like maybe you're not. What the adapter does is measure the voltage at the peak of the AC waveform, in the case of the coil primaries it's measuring the voltage for the few milliseconds the powepack is firing. Using only a multimeter on AC or DC volts won't give you any meaningful information for this test, you MUST use the DVA adapter in conjunction with a multimeter set to DC volts. (If you need it I can post the schematic for building one, there's only a few parts which are available at Radio Slack.)

FWIW, CDI test procedures say... (for motors 1979-88, no QS), to test orange wire with coil, and if test is 'low' test with "load resistor"... if test remains low, bad PwrPck or TimerBase... if test is 'good', bad coil.

That would effectively test the primary side of the coil, but not the secondary (high voltage) side. If there were a problem on the secondary side of a coil all tests would show good but that particular coil still wouldn't make a good spark, therefore the need for a spark tester.

 

[OldPcGuy]

Re: Load resistor - how used

Sorry Daselbee, I'm 'fighting' with a 1987 xp200 that starts great, idles fine (a tad fast for my taste, 1100), had carb issues that I believe I've fixed (kits+adjusted the floats), ran GREAT for about a day (better before I adjusted the floats...3 were totally 'whacked'.... didn't run hard and fast, just a couple hole shots, and some idling). Yesterday I noticed the 'internal' fuel filter does not 'fill up' with motor idling or at ~3k RPM..(??) The motor was stored for 10+ years and well 'cared' for in storage. Started getting it 'in shape' a few months ago, and had a mechanic come over to replace the water pump, check the lower unit (too much hefting for me to do alone). And he stated (??!!) flat out, it needed a PwrPck, so we put on one new CDI PP . Looking under the flywheel, things look 'fine'.. nothing burned/melted/falling off... lastly, the heat horn has a 'mind of it's own'... Sometimes 'chirps' at key turn like it should and is quiet... then other times, with cold engine the horn comes on and stays on. I've even had an instance where I turned the key, got the 'chirp' but didn't start the motor, just left the key in 'run' position... after 3-5 mins the horn came on and stayed on. Never DID start the motor that day, but tried the key every couple hours, and got full horn. Corrosion in the control box..??

I've got a meter, a DVA, spark 'tester', a new coil (for testing or use), and hopefully I'll get a timing light today... I'm running high test gas with pricey additive and good oil, using a 6 gal tank with 'fast' release OMC style connection (not enough fuel flow for V6.??) but hopefully by this afternoon will have plumbing installed to new below-deck tank using 3/8" ethenol resistant hose through fuel/water separator/filter.

Whew... and after all this, my neighbors are suggesting their 'favorite' mechanics..!!! In a couple weeks, I have to leave for a week and it's tempting to take the boat to a mechanic and ask to get it back running great. But, d_mn.. I would rather find the problem and get it fixed. As always, I KNOW it's right in front of me... just have to find it.

Thanks very much for you time, effort, and advice....

 

[daselbee]

Re: Load resistor - how used

But Old PC....you never say what it is doing now...running wise. You say it ran great for about a day...then you veer off to fuel filter, and horn.

What is it doing, and why are you focusing on spark, coils, etc right now?

Using the DVA, at idle, (or cranking speed), measure the voltage at the orange coil primaries, and POST the numbers for all six. Use the short jumper under the cap method I suggested, and measure from there to good engine block ground. DVA setup should be set on 200 vdc scale.

1 = xxx
2 = yyy
3 = zzz

etc.

 

[OldPcGuy]

Re: Load resistor - how used

Focusing on electrical because I THINK I've eliminated the fuel issues... won't know until I get some feedback on that. ie - inline fuel filter fills halfway when primer bulb pumped, but is almost empty when engine runs... is this normal..?? New carb kits installed, and floats adjusted. Engine starts easily, idles a 'little' rough and a little fast (1100rpm) for my taste, and is weak on hole shot, won't reach top end.

I built a couple of DVAs per the schematic on this web-site. I'm using it with a 'cheap' DMM...

Not knowing the correct cylinder numbering scheme, the DVA readings are as follows...

Idling at 1000-1100 rpm
Testing orange wire connected to coil (using pigtail) to ground (engine block)

Starboard bank of cylinders... (has 'old' powerpack)

Top 189.3 - 192.4 (has new coil)

Middle 208 - 216 ( had to switch meter from 200 to 1000 range )

Bottom 212 - 216

Port bank of cylinders... (has new CDI pwrpck)

Top 159 - 162

Middle 159 - 164

Bottom 157 - 161

 

[daselbee]

Re: Load resistor - how used

Ok....right off, I would say that those numbers are good for your purposes. "For your purposes"...what does that mean....well, there is not anything there that stands out as absolutely "bad". Or bad enough to cause your hole shot, and WOT problems.

MY OPINION ONLY.

What is odd is that you have basically two different readings...200v on the stbd side and 160v on the port. Now this MAY be caused by the CDI pack....I am just not sure on that...but your stator may have an issue also. The stator is the device that generates this high voltage in the first place. It is the source. And, there are two charge coils on the stator (Brown pairs of wires) that lead to the power packs. So two possibilities...the stator has a weak charge coil for the port side OR the CDI pack only outputs in the 160 v range.

One way to absolutely tell is to swap packs.

 

[OldPcGuy]

Re: Load resistor - how used

Ok....right off, I would say that those numbers are good for your purposes. "For your purposes"...what does that mean....well, there is not anything there that stands out as absolutely "bad". Or bad enough to cause your hole shot, and WOT problems.

Understood. I found it 'odd' that the new CDI pack was 'weaker' than the 'old' pack... someone here says they may be able to get me a used but "good" pwr pack cheap for 'test' purposes..

MY OPINION ONLY.

Understood.

What is odd is that you have basically two different readings...200v on the stbd side and 160v on the port. Now this MAY be caused by the CDI pack....I am just not sure on that...but your stator may have an issue also. The stator is the device that generates this high voltage in the first place. It is the source. And, there are two charge coils on the stator (Brown pairs of wires) that lead to the power packs. So two possibilities...the stator has a weak charge coil for the port side OR the CDI pack only outputs in the 160 v range.

One way to absolutely tell is to swap packs.

Understood. If the low voltage 'follows' the pwrpack, it's the power pack. If it 'stays', it's the starboard side charge coil of the stator..(??) But, as you've said, that may not be the source of my 'problem(s)'...???

Doesn't CDI recommend a couple tests for the "brown wires" from the stator..?? Resistance, and voltages..??
Should I do that before/after swapping power packs..??

So far today, the overheat horn has not come on... only chirped at 'turning key'. This horn issue has me 'spooked'.. the fact that it alarms when the engine is cold, but only sometimes...

 

[daselbee]

Re: Load resistor - how used

Sure absolutely....disconnect the brown pairs from the powerpack, insert suitable probes on the stator side, and measure the cranking voltage, brown to brown. If 200 on both sides, then the CDI pack is dropping the voltage down to 160. But this may or may not be bad. The CDI pack may be designed to only output 160. You can also measure the AC voltage at this point without the DVA adapter if you want. Switch your meter to AC 200v scale, and measure away. Post results.

If one brown pair is 200 and the other is 160, then definitely stator is weak on one of the charge coils. You will have to replace the whole stator tho. Individual coils are not changeable. Note that you may not see 200 on the browns...you will see some value that is close, but maybe not 200. The voltage waveform from the brown wires is entirely different from the waveform seen at the coils, so the DVA meter may read differently. It really doesn't matter for gross measurements...just see what it is, comparing the two sides.

It would only really matter for your purposes if one side was 200 and the other side was 95 or so. Big difference.

Once you get a handle on the bad component, get it replaced, and then you can sweat the small stuff. I am not sure I am making myself clear, but that is the way I approach problems like this. I look for big gross differences first, then hone in on the perfecting process.

EDIT:
Ummm you have a terminal strip right? If you have term strip, just probe right there, without disconnecting. Make sure you have two brown pairs...I am going by memory of newer loopers...1990 and up. Butterfly powerpack style. Not the dual PP style like yours.

EDIT 2: Don't sweat the horn problem. It is an intermittent short on a tan temp wire to ground, and you can tackle that later.

 

[OldPcGuy]

Re: Load resistor - how used

Easiest route for this afternoon... swap Pwrpcks... seems the 'weaker' side belongs to the CDI pack... as you said, CDI may regulate it's output to that lower voltage..(??)

NOTE: engine idles rougher, and at lower rpm. Before swapping coils, it idled at 1000-1100rpm.. after switching power pack, it idles at around 850, but idles rough enough that it's hard to get a good rpm 'read'... and seems like it 'might' stall...



DVA readings now ....

Starboard bank of cylinders... (has CDI powerpack, that WAS on port side)

Top 142 - 144 (has new coil) (was 189 - 192 with 'old' PP ** after switching, reading now below CDI specs)

Middle 158 - 160 (208 - 216 with old PP )

Bottom 156 - 158 (212 - 216 with old PP )

Port bank of cylinders... (has new "old" pwrpck, from other side)

Top 206 - 210 ( 159 - 162 with CDI PP )

Middle 209 - 213 ( 159 - 164 with CDI PP )

Bottom 209 - 215 ( 157 - 161 with CDI PP )

Could this indicate weaker/trouble coil(s) on starboard side..?? Moving the 'weaker' PP (CDI) to that side makes it run rougher and idle slower...

 

[OldPcGuy]

Re: Load resistor - how used

Set the spark gap to ~ 7/16" and tested all cylinders from end of spark-plug wire to tip of plug.

Port bank - (old PP originally on starboard side)

Top - strong spark, no apparent 'drop out'

middle - strong spark, no apparent 'drop out'

Bottom - strong spark, no apparent 'drop out'

Starboard bank - ( new CDI PP , swapped from port side )

Top - would not spark at all until gap closed to ~ 1/4" ( this cylinder tested low on orange wire at coil DVA test)
At 1/4" gap - spark strong with no apparent drop out.

middle - ~7/16" gap - strong spark, no apparent 'drop out'

bottom - ~7/16" gap - strong spark, no apparent 'drop out'

So, one cylinder, starboard top, with new coil, and new power pack, is showing weak "orange wire DVA test" (144v) and thus a weak spark (??) Is it weak enough to cause rough idle and that much loss of power...?

 

[daselbee]

Re: Load resistor - how used

Yes. Spark will not jump 7/16" on #1...the side with the low coil primary voltage...this is good. You have made excellent testing and diagnosis so far.

I am really starting to wonder about that CDI pack at this point. Gotta measure the brown pairs first tho.

It is very easy to swap coils with a known good cyl...say #3, just below....see if the weak spark follows the coil.

It should be easy to read the voltage at the brown pairs. My Vegas bet is that one pair will read high, the other low...

EDIT: Maybe....

 

[daselbee]

Re: Load resistor - how used

Set the spark gap to ~ 7/16" and tested all cylinders from end of spark-plug wire to tip of plug.

Ooopppssss....here is a problem.....do not test it to the tip of the plug...test from plug wire to tester to GROUND. All plugs should be out.

 

[OldPcGuy]

Re: Load resistor - how used

Yes. Spark will not jump 7/16" on #1...the side with the low coil primary voltage...this is good. You have made excellent testing and diagnosis so far.

I am really starting to wonder about that CDI pack at this point. Gotta measure the brown pairs first tho.

It is very easy to swap coils with a known good cyl...say #3, just below....see if the weak spark follows the coil.

It should be easy to read the voltage at the brown pairs. My Vegas bet is that one pair will read high, the other low...

EDIT: Maybe....

By "good" do you mean good it's "ok", or good-we're-finding-something...? It seems to me you mean good-we're-finding-something. Should I go ahead and move the coil, to see if the 'low' reading moves with it..?? Guess it's easy enough.

Now about the "brown pairs" to be tested... which wires are these..?? Where are they..?? and how are they tested..?? What test reading am I looking for..?? Voltage/Ohms, both..??

Are they from the stator/timer base and tucked under the flywheel..?? I noticed what appeared to be 'brown pairs' included in each connection to the power packs. One Pack had matching brown wires on "its" side of the plug (CDI pack I think). The other had black (or black with stripe) wires matching up with brown wires from stator/timing ring...

About your bet... when you say "one pair high, one pair low"... the power packs seemed to take their voltages with them when moved.. and the 'possibly' weak coil (#1) just got weaker with a 'possibly' suspect CDI PP moved to that bank. Are you betting the brown pair on (or to) the 'starboard' bank is low..?? The port side 'high'..?

Scary question (for me)... can the stator/timing ring/etc be intermittent..?? And if yes, would/could it be intermittent on a single cylinder basis..?? ie- be intermittent 'through' the PP to a particular cylinder, or 'cause' the PP to be intermittent on one cylinder..?? I guess for that matter, can the stator/timing ring/etc be 'weak' for one cylinder..??


thanks so much for your help...