Classic 50 spark advice?

[zorak]

Hi. I need some advice. I have an '88 classic 50 with spark troubles. My problem is this. No spark on #1 and #2. I constructed a DVA adapter and tested the stator and the triggers. Both are in spec per resistance and voltage output.That would seem to indicate the switchbox is bad by a process of elimination BUT, on a whim i pulled the green and the green/white wire off the switchbox and measured the voltage to the terminal on the switchbox.To my surprise i am now getting 150 volts to the aforementioned terminals.I hooked up the green/white wire and got spark out of coil #2 .Is there anything i should look for. I ran out of time tonite but i will remove the coils tommorrow to see if my suspicions are correct. I suspect some sort of wiring damage as the switchbox has clearly been replaced. I would assume that the switchbox would either work or not as it is potted and vibration shouldn't affect it. Any other opinions would be welcome as i was getting ready to order a switchbox .Thanks in advance.

 

[verado7]

Re: Classic 50 spark advice?

common failure on these motors to lose 2 cylinders - switchbox .i have the same motor and have gone thru the same thing .

 

[zorak]

Re: Classic 50 spark advice?

i originally thought switchbox but if i remove the wire from switchbox to coil #2 then #1 will fire. I have seen on my Onan engine that it has one coil with 2 spark leads.Both plugs fire at the same time whether that particular piston is at tdc or not. I am thinking that if one of the wires between coil and switchbox were grounded or 1 coil has a short to ground then that would kill the spark on both coils as i see no way that this ignition system could differentiate between #1 or #2 piston being tdc so both plugs #1 and #2 spark at the same time.I may be totally wrong on this one and i intend to do some more troubleshooting when i get home .Like i said earlier i get 150 volts plus at all 4 switchbox terminals with #2 disconnected at the box so i suspect that the wiring or coil may be my problem.

 

[zorak]

Re: Classic 50 spark advice?

Hi. i need some advice on my problem. Can a switchbox only have 1 circuit go bad. My switchbox will output the specified voltage for all 4 coils but will only fire on 3&4. If i unhook the wire from switchbox to #2 coil then #1 coil will fire.I have verified that all 4 coils will fire. i am stumped as i cant see how the switchbox terminal for #2 coil can have the proper voltage on it until i hook it up then it goes to zero volts at the box. i have checked the wiring from the switchbox to the coils visually and with a vom. I assume the box is bad but searching for anything similar already posted hasn't given me any insight.Thanks for reading.

 

[zorak]

Re: Classic 50 spark advice?

Thank you Verado for the response. I suppose i will just have to roll the dice and get a switchbox as i don't think my problem could be anything else i don't have any more ideas on how to be more sure that my switchbox is faulty other than to replace it and see.

 

[zorak]

Re: Classic 50 spark advice?

Hi all. I am still trouble shooting my problem and i think it is the switchbox however,something doesn't make sense to me. The CDI troubleshooting guide says to read stator voltage between blue and blue white and red and red white. I have seen several other websites and even a merc manual that say to check between blue and ground and between red and ground .Which one is correct. According to the CDI guide my switchbox is bad but all other sources says that the stator could be bad.I tend to trust the CDI information as the readings i get match their listed OEM specs perfectly ( resistance and DVA voltage).Thanks in advance for any help i can get.

 

[verado7]

Re: Classic 50 spark advice?

read between red/red white and blue /blue white the other advice refers to the red stator ( of death) dont buy the red stator - ever .

 

[zorak]

Re: Classic 50 spark advice?

Thanks. Yea i have heard about just how crappy the red stator is.I think it has to be the switchbox as i feel i have eliminated everything else as the stator and the trigger test within specs.Thanks for the help.

 

[zorak]

Re: Classic 50 spark advice?( update)

Re: Classic 50 spark advice?( update)

Just to help anybody out there haing similar issues.I ordered a new switchbox and now the engine runs on all 4 cylinders.I found a source for new switchboxes for $109.00 and it was NOT on ebay.