94 Mercury 115 no spark on #1 cylinder.

[stickydahc]

Hi guys. I have browsed around for a few days and can't seem to find the answer to my problem. I just picked up this 93 Nitro 180fs with a 94(?) Mercury 115. I knew it had no spark when I got it. After checking spark with a tester, I found I have spark on #2,#3, and #4 but not #1. I swapped coils around and still no spark on #1 but the original #1 coil sparked in the #3 position. I tested to the best of my knowledge, the voltage coming from the CDI and it maxes out my dmm. I'm sure that isn't the proper way, but thats all I have. The question is, do you guys think its the trigger or the CDI? Thanks in Advance ~Chad

 

[enginepower]

It could need both. You need a DVA so you can test this properly. Need to make sure the triggers ohm within specs and test the voltage output of them. Make sure the CDI is putting out the proper voltage. A bad trigger can damage a CDI and vice versa. Since you have spark on the other cylinders, I would think the stator is ok but I would still ohm and DVA test it as well. This is a great troubleshooting guide. http://www.cdielectronics.com/support/

 

[stickydahc]

Thanks enginepower. I'll see if I can come up with a da today. It just seems weird to me that I have what appears to be decent spark on 3 cylinders but it won't even begin to pop over. I figured it would run but have a bad miss but it won't even try to start.

 

[Texasmark]

You can make one. It's basically a "sample and hold" circuit. The trigger pulses are very narrow and far apart. A regular meter can't register that. But the DVA is merely:

A pair of wire leads, one for the trigger source you want to measure and the other goes to ground, bat - or engine block.

A 600v or so 1 amp or so, diode with the Anode lead (the end with the arrow part on the diode symbol, not the bar at the point of the arrow which is the cathode) connected to the positive DVA (you are making) lead.....that connects to the trigger signal/voltage.

Attach a .47 microfarad 600 v paper/paper-plastic capacitor lead to the bar end of the diode (cathode) along with one end of a 1/2 watt or so carbon resistor of 1 meg ohm give or take. The other lead of both the cap and res tie to your ground lead. The components aren't all that critical. You can put 2ea 1 microfarad 400v caps in series with each other....capacitor value is halved in series and voltage breakdown is doubled. Resistor.....just get close.

Set your Digital voltmeter on the 400 or so DC volt scale. The red lead of the meter goes to the connection of the diode cathode, cap. and resistor junction and the black lead on any ground mentioned including the other (lower) end of the cap or resistor.

Run your engine at idle or the specified rpm in the manual (don't forget to put the water and muffs on) and give it time to charge up the cap....a few seconds. Correct voltage value is in the manual. Will be several hundred volts. I don't have mine any longer or I'd tell you what the number is. If you need a quick manual you can rent online time from Seloc manuals......check out the icon at the upper right of this page.

Obviously keep your fingers off the hot side of the cap. Enough stored energy there to give you a good whack! If you switch from one cylinder to another in measuring, after you disconnect from the trigger source, give the cap time for the "bleeder resistor" to discharge it and let it recharge to the new level.

Radio shack or a tv repair shop will have your parts.

Good luck,
Mark

 

[stickydahc]

Thanks mark. I will have to try that. What would make only number one not have spark though? I would assume the trigger powers the cdi and cdi sends signal to each plug. Like I said I am getting signal from cdi and 2 3 and 4 have good spark. I don't understand why it won't even try to fire up with only one cylinder not firing. I would assume it would still try to run but it would run rough. This motor won't run at all.

 

[Texasmark]

My maintence manual for the triple 90 and 2+2 4 cyl higher hp engines had an interesting and somewhat confusing triggering circuit. I don't know why it was so complicated but it would send the series trigger current around in a loop and involve several cylinders rather than just have each independent. If you get a wiring diagram you can see what I mean.

So in answer to your question, the answer could be what I said. Somewhere in the recirculating loop is an open circuit which kills the system.

However, if you have fire on 3, I too don't understand why the engine won't start unless you have a different issue.

First thing is test: Is it fire or fuel. Pulling the cover off the air box and with a can of Sea Foam shoot into the carbs while the engine is cranking. If something happens you have a fuel problem also. If it makes no difference then stick with spark.

HTH,
Mark

 

[enginepower]

Like Tex said, try spraying some fuel in there (pre mix in a spray bottle is suggested) With 3 cyl sparking, it should run on the muffs. Even if timing is off or whatever the trouble is, you should be at least hearing popping or back fire so maybe you aren't getting any fuel either. If the engine has been sitting up, the float needles are probably stuck.

 

[bilge rat jim]

So.......back to the no spark issue. Go to page 82 of the CDI troubleshooting guide. Test the trigger resistance as set out in the guide. If the resistance readings fall within the specs (or close), move on to step 2- switching stator leads.

 

[Texasmark]

Like Tex said, try spraying some fuel in there (pre mix in a spray bottle is suggested) With 3 cyl sparking, it should run on the muffs. Even if timing is off or whatever the trouble is, you should be at least hearing popping or back fire so maybe you aren't getting any fuel either. If the engine has been sitting up, the float needles are probably stuck.

That's the beauty of Sea Foam. You can get it in aerosol and it has oil, naptha, and alcohol in it's makeup. I learned of it on here and the big guns recommended it. Been using it ever since with my gas from the pint can. Course if you have a plastic squeeze bottle a little pre mix is probably more accessible.

Mark

 

[stickydahc]

I finally had a chance to test things. I tested the wires running from each coil to cdi and got 0. I also tested the ground wires from each coil to ground and got 0. From all 4 trigger leads to ground i got "open". I got ~750 between Purple and white, and brown and black. I tested the stator wire green/white to white/green and got ~550. Where it says blue blue white, is that the wire where the green/white white/green run into the black box and are blue/white/blue out of the other side? I tested those and also got about ~550. I didn't see any other blue wires so I figured those had to be right. According to that troubleshooting guide that should have been open. What is that black box? I'm still waiting on my dva adapter to show up so i haven't had a chance to test for voltages yet. I also tried shooting fuel into each carb and starting and it didn't even try to kick over. I have about 130 psi of compression on all cylinders so I'm sure its a spark issue. It still boggles me as to why it won't even try to kick over.

 

[racerone]

Have you checked the flywheel key ??

 

[enginepower]

If you don't have an understanding of how things work (trigger activating SCR in switch box/stator providing voltage to do things) you need to follow the trouble shooting chart step by step. Even with that, lack of knowledge may lead to you needing to bring it to a mechanic.

 

[Faztbullet]

It just seems weird to me that I have what appears to be decent spark

It needs to jump a min. 3/8 gap as if not strong enough compression will keep spark from happening..From you description of ignition system you have CDM modules and each is its own little switchbox, so check them per the CDI manual as the one above/below the one not firing can be bad(and still be working) effecting the one not firing.If spark is weak (should be bright blue and pop) the stator is weak.

 

[stickydahc]

Alright guys I got it running. Not sure exactly why but it gets spark on all 4 now. Something must have been loose and with all the testing i must have tightened it back up. It starts right up and runs good in neutral and in gear on the muffs. I took it to the lake and when I put it in gear it either dies or chugs really hard for a bit then takes off. I ran it again today after putting a can of seafoam in it and it seemed to get better. I would have ran the whole tank through but it was in the teens this morning and I about froze after a couple hours. I assume the carbs are gummed up. I have never used seafoam before, but after reading on here about everyone raving about it, I figured I should give it a shot. Will it clean the cabs out completely or will I still have to pull them and clean them myself? Thanks for all the help and great info.