87' 115Hp inline 6 no spark on 3 and 4

[Clams Canino]

Re: 87' 115Hp inline 6 no spark on 3 and 4

Doubtfull But worth a quick check. Sounds now like it may well be a switchbox all the way issue.<br /><br />-W

 

[rodbolt]

Re: 87' 115Hp inline 6 no spark on 3 and 4

beats me.<br /> its difficult and occasionally expensive to splatter gun the testing procedures, thats why I dont swap parts around, its to easy to test them. when you start swapping stuff its to easy to get confused or create another problem.<br /> here in the salt pond if I dont HAVE to remove a fastener I usually wont touch it on a motor that old.<br /> in the mercury service manual it describes both the distributor and the ADI ign system and how they work as well as the correct test instruments and correct testing procedure. <br /> the CDI manual I referenced above is also a very good ign testing manual.<br /> the analog DVA sold by merc and sierra is not expensive at all and works well.<br /> for trouble shooting I prefer an analog peak reading meter as the meter movement reacts quicker and will show issues that dont show up on a digital meter. a digital is easier for a novice as its not polarity sensitive.<br /> but its all a matter of input/output.<br /> the switch box does not step up voltage just stores the rectifies and stores the current then releases it when triggered.<br /> that being said I have seen switchbox failures that took the stator with it and stator failures that smoked a switchbox.

 

[ColdFire]

Re: 87' 115Hp inline 6 no spark on 3 and 4

Clams and rodbolt, I would like to thank both of you for your help. Rodbolt I wouldn't mind getting the analog DVA but it is not a piece of equipment that I would use for anything else (and the boss at home might shoot me if I get another piece of electronic test equipment). I have a few digital meters and a nice digital O-scope with HV probes (I design embedded computers an analog circuits for industrial use) so if I can make do with the tools I have it would be nice. I can use the o-scope tonight to check the voltages again. I will also double check the grounds, and remove the idle stabilizer tonight.

 

[rodbolt]

Re: 87' 115Hp inline 6 no spark on 3 and 4

there is an odd trigger problem that can occur with dual wire coils, if one wire shorts to ground it can take out just one cylinder and still pass an ohms test. it will fail a loaded and unloaded peak reading test.<br />so anytime your fighting a dual lead coil try testing each leg to ground.

 

[ColdFire]

Re: 87' 115Hp inline 6 no spark on 3 and 4

Ok I didn't get to finish all of the test tonight but I did test the following with an o-scope:<br />stator voltages:<br />Blue = 162V low but with my home made DVA adapter it was correct.<br />Blue\White = 168V<br />now the red and red\white wires had pulses well over the minimum 25V<br /><br />now the good news when I removed the idle stabilizer I got spark back on 3 so one problem solved, now to figure out 4 & 5.<br /><br />Removing the bias wire did not help either so tomorrow night I will test the trigger and switch box outputs.

 

[ColdFire]

Re: 87' 115Hp inline 6 no spark on 3 and 4

Ok finished testing the trigger still ohms good and my scope checks show good voltages. so to add to the confusion I decided to swap the trigger wires for 4 and 5 and check for spark again. When I did this I started getting spark on all 6 so I am completely confused and fed up I will break down and buy the dva adapter and try again who has a good one?

 

[ColdFire]

Re: 87' 115Hp inline 6 no spark on 3 and 4

Ok, new DVA adapter cleaned all connectors here is what I came up with.<br /><br />DVA Voltages:<br />stator Blue = 235V Blue/white 200V Red= 32V Red/white= 34V<br /><br />Trigger voltages:<br />all about 2V on the outputs that don't have spark a little lower if I disconnect the wires and retest they come up to about 4.5V<br /><br />Switch box outputs all above 170 except 3 1.2V 4 and 5 about 148V.<br /><br />If I remove the bias wire I start getting spark on 5 and 4 and no help on three.<br /><br />so from these readings I am going to order 2 new switch boxes tomorrow. Looks like the trigger and stator are good.<br /><br />Thank you for the Help.