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50 hp Force no spark on cyl#2/2 only in idle. video attached

A

acalabro

New member
So I've had good luck with this (89-91) Force 50hp mechanically since I bought it used with low hours back in July of 2012 until a few weeks ago. I was out on the water and was fine until after I stopped, went to power up and it would only start on fast idle. If I brought the throttle back down to regular neutral idle position, it would sound like its missing and die soon after putting it in to that idle position. The only way to start it and keep it running was to throttle up to a fast idle, out of gear of course.
facepalm.gif

Back at home, I hooked up a spark checker and discovered that cyl #2 was losing spark upon putting in idle that I'm used to. I already replaced the coil for that cyl #2 and same result. I don't know what to go to next and I really don't want to bring it in to a shop but if I have to I will. My guess is that it could be the CDI box I guess but I don't know how to check those or if it's even possible and don't want to buy a used one for $150 before I know that's what it is.
Here is a video of the symptoms on youtube: 90' Force 50hp missing on idle - YouTube , sorry for poor quality.

I know that this is not a fuel problem because I can see that it is simply not firing in that idle position. Any help appreciated thank you
 
Do a compression test and then go to CDI ignition . com and they have test procedures for your motor. If you need to buy these people have stuff cheap. Standard Magneto Sales Company, Inc.
4119 West Grand Ave., Chicago, Illinois 60651
Phone 1-800-MAGNETO
(1-800-624-6386)
Fax 1-773-235-2996
 
Jerryjerry05 said:
Do a compression test and then go to CDI ignition . com and they have test procedures for your motor. If you need to buy these people have stuff cheap. Standard Magneto Sales Company, Inc.
4119 West Grand Ave., Chicago, Illinois 60651
Phone 1-800-MAGNETO
(1-800-624-6386)
Fax 1-773-235-2996
Click to expand...

I see they say to check trigger and stator resistance but it doesn't explain (which wires to test). My motor is pretty simple being that it's two cylinder. I have two service manuals for it and plenty of tools except a DVA peak voltage adapter. If that's what it takes I guess I will buy one. Anyways, the trigger on my motor, according to the diagrams in the manual say that it(trigger) has two wires coming out for each cylinder. Each set of these wires coming from the trigger go to two wires going to CDI box. I have tested resistance before for the coils but I don't know which ones to check for the trigger. Which ones do I check? Thanks for any help bud
 
Force

Prestolite ADI Ignitions 1984-1992
General

  1. Check for broken wires and terminals, especially inside the plastic plug-in connectors. We recommend that you remove the pins from the connectors and visually inspect them.
  2. Check the flywheel for a broken or loose magnet.
  3. Disconnect the kill wires from the CD and connect a DC voltmeter between the kill wires and engine ground, turn the ignition switch on and off several times. If, at any time, you see voltage appearing on the meter, there is a problem in the harness or ignition switch. At NO TIME SHOULD YOU SEE BATTERY VOLTAGE ON A KILL CIRCUIT.
  4. Visually inspect stator for burned or discolored areas. If found, replace the stator. If the areas are on the battery charge windings, it indicated a possible problem with the rectifier.
IF NO FIRE ON ANY CYLINDER:

  1. Disconnect kill wire AT THE PACK.
  2. Check for broken or bare wires on the unit, stator and trigger.
  3. Measure DVA voltage of the stator between the output wire sets. With everything connected, readings should be approximately 180 volts or more. Resistance readings between the stator wire sets range from 680 - 800 ohms.
  4. Disconnect the rectifier. If the engine fires, replace the rectifier.
NO FIRE OR INTERMITTENT ON ONE CYLINDER:

  1. Check stator and trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-5V or more), stator reads 680-800 ohms, DVA 180V or more from blue to yellow.
  2. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.
NO FIRE ON TWO CYLINDERS:

  • If two cylinders from the same CD unit will not fire, the problem is usually in the stator. Test per above.
ENGINE WILL NOT KILL:

  • Check kill circuit in the pack by using a jumper wire connected to the kill wire coming out of the pack and shorting it to ground. If this kills the pack, the kill circuit in the harness or on the boat is bad, possibly the ignition switch.
COILS ONLY FIRE WITH THE SPARK PLUGS OUT:

  • Check for dragging starter or low battery causing slow cranking speed. DVA test stator and trigger.
HIGH SPEED MISS:

  1. DVA check stator voltage to each pack at high speed. If it exceeds 400 volts, replace the pack.
  2. Disconnect the rectifier. If the engine fires smoothly, replace the rectifier.
Two Cylinder Engines with Combination CD Module with Built-in Ignition Coils
(1984-1988)
NO FIRE OR INTERMITTENT ON ONE CYLINDER:

  1. Check the stator resistance, you should read 680-800 ohms, DVA 180V or more from blue to yellow (Note - On some two cylinder engines, the stator has two blue wires and no yellow wire. The stator will read from blue to blue). All stator wires should read open to engine ground.
  2. Check the trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-5V or more), and open to engine ground.
  3. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack
ENGINE WILL NOT KILL:

  • Check kill circuit in the pack by using a jumper wire connected to the kill wire coming out of the pack and shorting it to ground. If this kills the pack, the kill circuit in the harness or on the boat is bad, or possibly the ignition switch.
    Force

    Prestolite ADI Ignitions 1984-1992 (Continued)
    Two Cylinder Engines Using Separate Switch Boxes and Ignition Coils

    1. Disconnect the kill wires from the CD and connect a DC voltmeter between the kill wires and engine ground, turn the ignition switch on and off several times. If, at any time, you see voltage appearing on the meter, there is a problem in the harness or ignition switch. At NO TIME SHOULD YOU SEE BATTERY VOLTAGE ON A KILL CIRCUIT.
    2. Check the flywheel for a broken or loose magnet.
    3. Check for broken wires and terminals, especially inside the plastic plug-in connectors. We recommend that you remove the pins from the connectors and visually inspect them.
    4. Visually inspect stator for burned or discolored areas. If found, replace the stator. If the areas are on the battery charge windings, it indicated a possible problem with the rectifier.
    IF NO FIRE ON EITHER CYLINDER:

    1. Disconnect all kill wires AT THE PACK.
    2. Check for broken or bare wires on the unit, stator and trigger.
    3. Measure DVA voltage of the stator between the output wire sets. With everything connected, reading s should be approximately 180 volts or more. Resistance readings between the stator wire sets range from 680 - 800 ohms.
    4. Disconnect the rectifier. If the engine fires, replace the rectifier.
    NO FIRE OR INTERMITTENT ON ONE CYLINDER:

    1. Check the stator resistance, you should read 680-800 ohms, DVA 180V or more from blue to yellow (Note - On some two cylinder engines, the stator has Iwo blue wires and no yellow wire. The stator will read from blue to blue). All stator wires should read open to engine ground.
    2. Check the trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-5V or more), and open to engine ground.
    3. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.
    ENGINE WILL NOT KILL:

    • Check the kill circuit in the pack by using a juniper wire connected to the white kill wire coming out of the pack and shorting it to ground. If this kills all fire from the pack, the kill circuit in the harness or on the boat is bad, or possibly the ignition switch.
    COILS ONLY FIRE WITH THE SPARK PLUGS OUT:

    • Check for dragging starter or low battery causing slow cranking speed. DVA test stator and trigger.
    HIGH SPEED MISS:

    1. DVA check stator voltage to each pack at high speed. If it exceeds 400 volts, replace the pack.
    2. Disconnect the rectifier. If the engine fires, replace the rectifier.
    3. Check for broken wires and terminals, especially inside the plastic plug-in connectors. We recommend that you remove the pins from the connectors and visually inspect them.
    4. Check the flywheel for a broken or loose magnet.
    5. Disconnect the kill wires from the CD and connect a DC voltmeter between the kill wires and engine ground, turn the ignition switch on and off several times. If, at any time, you see voltage appearing on the meter, there is a problem in the harness or ignition switch. At NO TIME SHOULD YOU SEE BATTERY VOLTAGE ON A KILL CIRCUIT.
    6. Visually inspect stator for burned or discolored areas. If found, replace the stator. If the areas are on the battery charge windings, it indicated a possible problem with the rectifier.
 
Jerryjerry05 said:

  • NO FIRE OR INTERMITTENT ON ONE CYLINDER:
    1. Check the stator resistance, you should read 680-800 ohms, DVA 180V or more from blue to yellow (Note - On some two cylinder engines, the stator has Iwo blue wires and no yellow wire. The stator will read from blue to blue). All stator wires should read open to engine ground.
    2. Check the trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-5V or more), and open to engine ground.
    3. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.
Click to expand...
I saw this guide on the website you copied and pasted from however my question is, on number 2, it says "trigger wire sets read approx. 50 ohms between the wire sets" does that mean to test resistance between the two coming out for each cylinder becoming a "set"? Like I said before there is 4 coming out of the trigger, each cylinder gets two of those according to manual diagram. First they go to cdi box, then cdi to coils then coils to spark plug. So when it says to test a "set" does that mean the 2 wires designated to same cylinder?
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