2003 J50PLSTD fails charge coil test.

bigdog009

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2003 I have a 50 HP Johnson and I cannot get the motor to run or briefly run at a rough idle for 20 to 30 seconds. Some history: This spring took boat out and it "coughed" one time then went on with normal operation. Second time out it coughed twice then ran for about two miles and then quit. Would not start. Took it to the water a week later after changing plugs and replacing fuel filter and finally got it to start but when in gear (forward) full throttle would barely push the boat.
I have accomplished the following;
Suspected faulty fuel but did not know for sure:

Fuel:
1. changed fuel filter with transparent filter
2. Drained and flushed tank and replaced fuel with non ethanol fuel.
3. Replaced primer bulb and hose assembly ( original equipment was weathered and seemed weak).

Ignition:
I have maintenance manual: 1. changed spark plugs and ohm check coil to be within range of factory specs. 2.plug wires are reading "0" resistance;
3. checked spark with spark testing tool. settings of 17 to 20; continuous spark blue strong, loud report during operation on each cylinder.
5. When I removed spark plugs,they are wet with fuel. I am wondering if there is a way the choke could be stuck or something like that. The Illustrated parts breakdown of the carburetor looks simple.

I am the original owner and this year is the first year I have had any issues with the motor operation, excluding trim and tilt.

recap I have cleaned the fuel system ( not carburetors or VRO) I have bench checked ignition system.I have a maintenance book that states that the charge coil has to read 800 to 1000 ohms. I can get 395. Since temp is stated to be 68 degree f. can this reading be good at 85 F?
 

AlTn

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Re: 2003 J50PLSTD fails charge coil test.

suspect that 17-20 are KV readings and your ignition should be capable of 30KV or more...is the air gap adjustable in your spark tester?..if so, open it to 7/16" and recheck...post back
 

bigdog009

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Re: 2003 J50PLSTD fails charge coil test.

I got brave and followed my instincts for the failed charge coil test and it worked. I can achieve idle and it does not stall when I put it in gear (test hose connection only) I am wondering if timing could be an issue. The engine will run up to the peak idle settings by the book then caugh and start over again. If it were a car I would be looking for a vacuum leak or a idle air solenoid etc... Any ideas you wisdom is appreciated
 

AlTn

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Re: 2003 J50PLSTD fails charge coil test.

no direct experience with your engine, but what you are describing sounds like a "lean sneeze". I'd suggest opening the slow speed idle valves 1/2 - 1/4 turn at a time and seeing what effect this has on your idle. Also check all the fuel hoses possible cracks and for tight fittings.

If you've set the timing by the "book", I'd try fuel adjustments now. In my experience 2 strokes are more sensitive to this than 4 strokes.
 

bigdog009

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Re: 2003 J50PLSTD fails charge coil test.

Timing I cannot do with out specific equipment and I believe it is under load. I have checked range of adjustment on timing advance or idle advance @ 2.5 inches and it is exact. So is the rest of the "alignment" adjustments. I will explore your idea of "lean sneeze" and see what I can find with the adjustments.

The tachometer is also an issue. I lost it when the charge coil went away. What powers the tachometer on these engines, the book does not state. I want to think it is the position transmitter for the crankshaft but it could be anything including the power pack. Any information would be appreciated
 

AlTn

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Re: 2003 J50PLSTD fails charge coil test.

the tach signal comes from the a/c coils < charging coils > in the stator. These run to the rectifier which generally go to a terminal block mounted on the side of the engine. Don't know enough about this subject to advise you, but I've read on the forums that a bad rectifier can cease providing a signal to the tach. Do a seach using the search feature, or maybe your manual has one as well, on the procedure for checking the rectifier. You certainly want to test it first before blindly purchasing one.
 

bigdog009

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Re: 2003 J50PLSTD fails charge coil test.

Well funny you mention that and this will make things come full circle. Last year I had an issue with tach running off scale high or elevated rpm. ts to a voltage regulator I thought it was out of parameters slightly but I changed it anyway. Issue went away and for a while but began to be an intermittent issue. With all of this debacle I can see that my original issue was probably a charge coil. I still have my old VR and will install it ( cannot hurt). Will try it again. I have been challenging myself to the VR but needed reassurance from other minds kind of brain storming. I have read the the charge coils like any other coil will have issues with surface damage where the strips or winding's touch or loose connection increasing or decreasing the amount of resistance required to function normally. I have also found that OEM charge coils in earlier models have less heat dissipation that newer model coils and relay due to varnish, and construction and less airflow by design. If I can find the research again I will post it for someone else to find and help solve their problems. Will advise on lean sneeze and Tach this weekend. We are experiencing flooding rain here 1 inch per hour
 

bigdog009

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Re: 2003 J50PLSTD fails charge coil test.

AITn:
I took your advise. adjusted fuel/air mix on both carbs, runs like a Cadillac or better that it did when it was new. Follow up issue, Tach still inop, charging estimated 5000 rpm @ 18V and voltage changes with rpm. Did not run to long just made sure engine power and idle were good under load and I was concerned about smoking charging circuits. I am considering changing THE VR but I am looking back at my basic automotive/diesel electronics training and wondering if ignition switch may be the culprit or at least a associated system malfunction. I say this due to I can turn the ignition switch on and off and I get voltage indication on the tach but no rpm indication after start. I did a wire trace and cannot find any fuses or shunts and the guage and switch are the only other real functional point of failure. I had replaced the Vr last year for tach issues (My inaccurate TS) as stated before. @ 135.00 per VR it does get expensive. Your thoughts please. TACH has only two connections and a cyl and pulse selection which have not been disturbed along with the test warning alarm ind lights.
 
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AlTn

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Re: 2003 J50PLSTD fails charge coil test.

wayyy out of my element here, although 18 v. doesn't sound like much regulating is going on, seems like 14v. or so would be normal. I'd suggest you use the search feature for testing the VR, maybe cdi electronics has a procedure on their site < cdielectronics.com >. If no one chimes in you could start a new thread on how to test the VR and tach.
 

bigdog009

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Re: 2003 J50PLSTD fails charge coil test.

I am certain about the charging voltage. 12 @ 4 or 12 amps volts charging systems charge at 13.86 vdc. If voltage follows throttle movement then there isn't any regulating going on. I finally found the section in my book that depicts proper charging and it should be approximately 14 volts and a range of 12+vdc to 14 vdc indicated it will rise from idle to 2000 rpm per running test under load. So with my outing the other day I am way out of bounds. I have just replaced the VR with the old one I have and I am going to do a test with just flush valve for rpm indication. I think I can place a load on the charging system with a adapter from the 12 v power outlet in the boat and the lights maybe. If charge works and tachometer does not then I will go to the tachometer but I really hope this will work. I want to clean her up and get on the water and do some serious fishing.

May I ask what type of craft you have?
 
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bigdog009

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Re: 2003 J50PLSTD fails charge coil test.

OK great news. OLD VR was good. I have tachometer and charging within limits. Valuable lessons learned with this. Get a darn book and follow it. Charge coil was problem the whole time. For further info, if a coil ohm test low as in 50% of low range limit or more for example the coil has issues probably shorted winding's. Example ohm test for 50HP johnson charge coil 800 to 1000 ohms. My reading 375 ohms on a good day at 73F. I have found that checking on a warm motor will change the test. Carb adjustments in 1/8 turn increments on 2 cycle motors by book screw all the way in (clockwise) and then 3.5 turns out (counter clockwise).

Thank you AITn
 

AlTn

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Re: 2003 J50PLSTD fails charge coil test.

good deal bd..thanks for the info and the finished results of testing...threads with no end results don't lend much knowledge...as for current craft...ain't got airy...I depend on my fishing buddies for test mules as far as test crafts go and these are 14' alum. vhulls...besides the 2 cylinder engines I purchase and piddle with, I help them maintain theirs...I couldn't agree more with your statement concerning Factory Workshop Manuals. For a novice the Seloc manuals have many teaching pointers as well, they're just "difficult" to sift through for specific info. It's probably there, just time consuming to find.

Best of luck
 
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