Charging coil shorted?

[Maxx99]

hi, i am trying to fix a misfire at idle. I have a 1997 60hp Vro johnson. i checked the resistance of the coils and they check out with the book. i also checked the charging coil resistance, with the wires unhooked. 0.5 ohms, the book says 300 or so, does this seem right? can this cause a problem at idle in gear?

any help would be greatly appreciated. thanks matt

this is the battery charging coil i am testing. not the cdi coil

 

[Big flop]

Re: Charging coil shorted?

The wires you tested were yellow? Battery charge wires.
Ignition coils, brown.
Quick start/slow orange. If applicable.
If you have a low speed sneeze could be lean fuel condition.
Ignition miss check small orange wires going to coils,
clean connections.
Make sure pack and coil grounds are clean and tight.
A cracked coil you can see jump to ground in the dark.

 

[Maxx99]

Re: Charging coil shorted?

yes the wires are yellow.
the motor runs fine for a few secs, then it kicks then runs fine again. its kicks enough to shake the whole boat. it will do this up to about 1/4 throttle or so, then it smooths out and runs fine above 1/4 throttle. is that what you mean by lean sneeze?

it only does it in gear in the water.
i checked the connections at the coils on the orange wires, they are spotless, i cleaned them anyways, and greeased them with dielectric grease. also checked the spark plug wires, they are clean and tight as well.
also checked timing, 4-5 ATDC at idle, after the quick start gives way, and 17 BTDC at WOT, seems correct.
i will check the grounds tonight if its not raining.
thanks for the input
matt

 

[Maxx99]

Re: Charging coil shorted?

lets see what else have i checked. compression is 115 roughly on all cylindars when warm. changed all fuel lines and have a new fuel tank. took carbs apart and cleaned them with spray and compressed air, didnt see anything in the carbs. i tried adjusting the low speed idle jets, no difference at all on the jumping problem.
i think i seen the timing light miss a beat when timing it, unless my timing light has a problem.
on top of the carbs there is a flat plastic plate with an orfice on the side of them, i blocked each one off with my finger and the motor bogs down a bit, still jumps though.
i assume that is the idle orfice?

 

[metriccrescentwrench]

Re: Charging coil shorted?

i think i seen the timing light miss a beat when timing it, unless my timing light has a problem.

That's an important clue pointing directly to an ignition problem. I had the same symptoms and it was a bad timer base. HOWEVER, before you go spending hard earned cash on a timer base make sure you go through the ignition system diagnostics which are spelled out in the factory service manual - the problem could also be a power pack or coil. You'll need a DVA adapter for your multimeter (I've heard they're around $30 or you could build one for under $10), what that does is takes a voltage measurement at the peak of the waveform as the ignition is firing for a few milliseconds each revolution. Essentially the procedure is to measure the voltage "spike" that the timer base generates to fire the transistors in the power pack, and then you'll measure the voltage coming from the power pack to the coils.

 

[Maxx99]

Re: Charging coil shorted?

so about the charging coil with the yellow wires, you guys think that is ok? or it is shorted.?

also, i have a amprobe voltmeter with peak, min and max voltage measurement capability. that should work ya think? or i have an oscilloscope, that will work for sure.

its raining here so i will check it if it ever quits, supposed to rain all week though.

thanks for the input, i will get back with you.
matt

 

[Maxx99]

Re: Charging coil shorted?

ok i did some checks.
did this with 2 different meters and got the same readings. Fluke 77 II

Brown - Brown/yellow = 5.66k ohms
Orange - Orange/black = 374 ohms
ok now red lead on white wire always for the next 3 tests

White - Purple = 7.18M ohms
White - blue = 6.92M ohms
white - Green = 2.11M ohms

not sure what the Black/white wire is for but i checked it also to the white wire and its 440 ohms


i spun the flywheel by hand a few times and triple checked readings and they are the same.

what do you guys think?

 

[Big flop]

Re: Charging coil shorted?

Sorry i dont have a manuel for that motor.
did you get the test sequence from a manuel?
It sounds right but timer base wires are
blue top cylinder
purple center cylinder
green bottom cylinder
green wire looks very low ?
the two yellow stator wires(battery charging) look ok
I have seen low ohms on timer base before that still runs ok
maybe re test after its warm?
if the pack has a stuck switch in it you can tap it
with a screwdriver handle and make it miss?

 

[Maxx99]

Re: Charging coil shorted?

i have a solec manual, but its not all that good..
but i downloaded the cdi ignition troubleshooting guide. here is what it says it should be

brown-brown/yellow should be 450-550 and i have 5660 ohms
orange-orange/black should be 450-550 and i have 374 ohms
white-purple should be 1.1M-2.4M but it says this can depend on the meter you have, so as long as the purple, green, blue wire are within 10% of each other they are good. of course mine are not as i stated above.

i downloaded 2 different troubleshooting guides from 2 different places and they both say the same thing..

does $169.90 sound ok for a price on a timer base..?

my stupid solec manual says it should be 650-850 ohms for the purple,green, blue wires, and that isnt even close..

 

[metriccrescentwrench]

Re: Charging coil shorted?

also, i have a amprobe voltmeter with peak, min and max voltage measurement capability. that should work ya think?

No. Multimeters read the RMS voltage of an AC waveform, which is kinda sorta an "average" value. In peak mode it's holding onto the highest RMS value it saw over a period of time. What matters in diagnosing ignitions is voltage at the instant the various components "fire". Since each cylinder fires for only a millisecond or less out of each revolution your meter won't be showing anywhere near a correct value. That's where the DVA adapter comes in.

or i have an oscilloscope, that will work for sure.

Yes, that would work. If you can get the scope to trigger correctly then you'd measure the value from zero to the top of the waveform.

I'm not familiar with your particular engine, but I very recently went through all off the ignition testing for my '90 200 and assume that it ought to be at least similar. For testing the timer base you'll disconnect the connectors and look at voltage (with the DVA adapter or a scope) from white to purple, from white to blue, and from white to green while you crank the engine. I don't know what yours should be (OMC factory manual for mine calls for 1.2 volts), but they should all be approximately equal.

my stupid solec manual

It would be well worth the money to find a real live OMC factory manual.

 

[Maxx99]

Re: Charging coil shorted?

Yes I will get a better manual. You said you can make a dva adapter. What do I need a diode and a cap?

 

[metriccrescentwrench]

Re: Charging coil shorted?

1N4004 diode, 2.2 uF or thereabouts cap rated at least 250 V, and a 1M or so shunt resistor across the cap to drain the cap.

Someone posted the schematic on one of the iboats forums, you should be able to search for it if you need it.

 

[Maxx99]

Re: Charging coil shorted?

ok thanks, got all the parts and assembled it tonight, waiting on rain to stop now for testing.

should i just test the 3 orange wires on the primary of the coils first? if they are ok then i am good? yes?

if there is a problem then i need to check at the timer base to determine it its the base or the pack correct?
now here is the kicker, it doesnt seem to misfire on the muffs, only under load and under 1/4 throttle, so am not sure if the reading here is going to tell me if its good or not, but its a start.

i have been reading about the link and sink procedures in the forums here, and they all say the timing must move before the throttle plates. mine do not, i dont believe this is the misfire problem cause at idle nothing has moved yet anyways. here is my problem, i dont have a adjustable idle stop screw, no spring on it its just ran all the way in tight, and the parts picture shows the same thing. so if i try to adjust the throttle linkage to make it move the timing first i have to adjust it ALOT. make any sense? hard to explain on the forum.

 

[metriccrescentwrench]

Re: Charging coil shorted?

Well, since you saw the timing light missing a beat every now and then it's a pretty sure bet that it is misfiring. It's just that you don't notice it as much.

If there's an ignition problem you'll likely see a lower voltage on one of the orange wires than the other two (this has to be checked with the orange wires either hooked up to the coils or else going through a 10 Ohm 10 watt resistor to simulate the load of a coil). I'd check it both idling and cranking the engine with the plug wires pulled.

If you see a difference then backtrack to the white-blue, white-green, white-purple measurements. Like I said, I'm not sure what the spec is on that for your engine, but they should all be pretty close. If it's bad one will likely stand out, that will mean the problem is the timer base. If the timer base is good, and if the stator is good that pretty much narrows it down to the power pack.

(You do still need to verify you're getting enough voltage out of the stator's brown wires - I'd think that spec would be in the Solec manual)

 

[Maxx99]

Re: Charging coil shorted?

ok here is what i got with the homemade DVA adapter and a fluke meter set on dc volts.
i am just cranking the engine with the plugs in and evything hooked up
Brown-Brown/yellow = 286VDC Peak
Orange-orange/black = 21.86VDC Peak
Cylindar #1 = 217Vdc
Cylindar #2 = 216Vdc
Cylindar #3 = 215Vdc

i know, your going to tell my to get a new timing light, and then take the carbs apart right?>

one thing i did notice is that the red lever on the primer solenoid is cracked, and it looks like it leaked a small amount of fuel out as well.

i took the carbs apart, now i havent put gas in it this year, or ran it at all yet, just cranked it for the dva test.
the bottom carb had a little gas left in it, the others were empty cause i ran it empty when i stored it. there was a water mixed in with the gas that was left in there from last year. could water cause it to jump around like that?

 

[Maxx99]

Re: Charging coil shorted?

let me know what you think when you get some time. thanks

 

[metriccrescentwrench]

Re: Charging coil shorted?

could water cause it to jump around like that?

Water will make it run like total crap. A filter/separator is a good fix for that, I've got one from wally-world on my fishing boat, and a Racor with a clear bowl on the Checkmate.

 

[Maxx99]

Re: Charging coil shorted?

Ok so you would say those readings are/good correcct. I put the carbs backs on today along with all new fuel lines. Started it up and it still misses. New gas tank and fuel as well. I have to have the low speed jets at about 1.75 turns out to run good.
Can a coil still bet the culprit even though the dva readings are good.

 

[AlTn]

Re: Charging coil shorted?

yes...coils, plug wires, plug boots....are all still in the equation...powerpack too as it can act up once hot....you can heat it with a hair dryer or heat gun to see if your dva values change....if your timing light is an inductive one, with the engine running, clamp to each wire in turn and look at the flash..if it's sporadic on 1 or more cylinders you'll have more info. to go on

 

[Maxx99]

Re: Charging coil shorted?

Ok thanks. Don't believe its a heat issue. Does it as soon as I start it up.