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

[ColdFire]

I noticed a rough idle the other day so I went over the motor today and I found no spark on 3 & 4. After following the seloc manual and trying to digest all of the information on here I am just getting myself confused. I've got good compression on all 6 110 to 115, the coils test good and when I test the stator and trigger they ohm out good. I don't have a DVA but I have access to a fluke meter with a peak setting will this work? I plan on testing the rectifier in a couple of hours. Is there anything else I should be looking for or that I can test with out a DVA if the fluke won't do it.

 

[Kenny Bush]

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

Sounds like you may have a switchbox problem. If your good, you can trace down the good circuits, and hook #3 & #4 on it, to make sure the circuit is good. If 3 & 4 work on the other circuits, then your switchbox is bad....

 

[ColdFire]

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

I will get to try the voltage test tonight... but I was guessing the trigger since 3&4 are together on the trigger. 3&4 are on different switch boxes, so I would guess that I would have to have both switch boxes bad inorder to see both 3&4 fail, right?

 

[andy6374]

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

IF it was the trigger you would have no spark at all. Follow BushCat's advice. Swap the wires leading from the switchbox to the #3,4 ignition coils with the wires leading to #1,2 (for instance). IF the spark condition jumps to #1,2 then the switchbox is bad, if it stays then the coils are at fault

 

[ColdFire]

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

Ok I tested the coils that way and the spark condition followed the outputs. conversly can I swap the inputs to the switch boxes... since it is the last output on both switch boxes I have a hard time believing they both failed the exact same way. If I swap the switch boxes around I still don't have a valid test since it is the last output on both that is affected. Either way I will know more tonight.

 

[Clams Canino]

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

That might yet be a trigger issue. Ohm out the trigger as per the manual. <br /><br />A single trigger coil can fail and take out 2 cylinders one on each box. Each coil runs 2 cylinders. On this one Andy is not correct.<br /><br />-W

 

[ColdFire]

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

Well the ohm test was ok with my el'cheap'o meter but I am borrowing a nice fluke and see how it reads that way.<br /><br />Clams how about swapping the inputs of the switch boxes to rule them out? with out the manual in front of me I believe they are the violet, white and brown wires.

 

[ColdFire]

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

ok with the fluke the all of my test come in at 1300 with in the test range of 1100 - 1400, for the trigger.<br /><br />But the stator is is only reading 5500 ohms for the blue and red leads when it should be 4500 - 6200 and 5000 for the blue/white and red/white should be 5400 - 6200<br /><br />I've also swapped the stator wires (blue and red to blue/white and red/white) from one pack to the other and did not see the spark problems move.<br /><br />I also noticed an intermitant spark on #1 so I am guessing it is the stator.<br />Does this sound alright or should I try a couple more test before I hunt down a stator and a flywheel tool?

 

[Clams Canino]

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

Yes the second stator reading sounds a bit low.<br />I'd start there... but know you could be in for a tough one.<br /><br />-W

 

[ColdFire]

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

clams I don't like the sounds of that... what else do you see in my future should I grab an extra switch box. <br /><br />I will start looking for a stator, I have seen a lot of references to a red stator kit is that something I should be looking for? The serial number is 0B110378. I have found a part# of 174-5456 for the stator unless there is a place to pick up a good used one.<br /><br />BTW what is the best way to hold the flywheel while you are trying to remove the nut?

 

[andy6374]

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

Originally posted by Clams Canino:<br /> That might yet be a trigger issue. Ohm out the trigger as per the manual. <br /><br />A single trigger coil can fail and take out 2 cylinders one on each box. Each coil runs 2 cylinders. On this one Andy is not correct.<br /><br />-W

Is this just with inline triggers? I thought for sure, at least on my V6 Black Max 88', that if the trigger was bad I wouldn't get spark at all consider all the trigger coils are interconnected or least I was told something like this before on this forum.<br /><br />Sorry about the bad info...It can be hurtful<br /><br />-andy

 

[ColdFire]

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

Andy I'll take any advice I can get, this site has such a great wealth of knowledge that it can overwhelm you, if you do a search look out, it is a guarantee that someone else has had a problem on a motor similar to yours and all of that inforation mixed in with what the manuals put out can really get a persons head hurting and tie that in with the marginal reading I am getting and look out but that is what I like about my set up, the motor and boat have been relativly easy to work on... nothing like the vehicles that I own, were I have to be a contorsionist just to change the plugs

 

[snpr762]

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

Did you get the no spark solved? Just curious what you found. I have the same problem with a 40hp 4cyl with 3&4 no spark. I have the Mercury service manual but all it has for tests is the static resistance tests that you mentioned.

 

[rodbolt]

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

the trigger circuits are just that, they trigger the SCR's in the switchbox to turn on. they are controled by the physical relation to the inner hub on the flywheel. each trigger coil pair of wires control 2 cylinders. lose a trigger and 2 cylinders drop off. the stator windings are wired in pairs to the switch box. you normally only lose one bank or 3 cylinders.the stator windings just provide AC current to the switch box, the box rectifies and stores the current, the trigger releases the current to the coil primaries where its further stepped up in the coil secondaries and ultimatly is able to create an arc path to ground.<br /> if you will notice one pair of switch box leads are yellow sleeved. this is to aid in repairs and installation to keep the two boxs seperate.<br /> two things ya need are a DVA meter or an adapter and the correct service manual. I have seen the resistance specs be ok and the voltage output be bad.<br /> CDI has a good reference book on testing that system as well. look for wbk 2004 list price is 19.95.

 

[ColdFire]

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

I just haven't had the time or the $$$ with christmas coming up. I am hoping to find either a good parts motor this winter or just bitting the bullet and buy a new stator this feb. <br /><br />Rodbolt, I have tested the trigger circuits and they appear to be good just a little low, I am still leaning towards the stator being weak.<br /><br />I've also fabricated a flywheel pulling tool from a lifting eye, and it worked like a charm so I am all set once I get the parts, my 4 year old is really wanting a "My Little Pony" and a couple of other MUST HAVE ITEMS so the parts will wait

 

[Laddies]

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

On I/6 or V/6s a bad stator will effect 3 cyl= 1 switch box, a bad trigger will effect 2 cyl 1 on each switch box, 1 cyl is a box or a coil, a high speed miss is usally a rectifier. These a general rules of ign. service. OHM meters are unreliable to test the systems it takes a DVA. Always disconnect the kill wires from the boxs and ck the bias (ground wire) between the boxs

 

[snpr762]

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

I think rodbolt,clams,andy & laddies on the right track. In the past,I have done a static resistance test on these type items and they test out of spec, yet they are not the issue. I was hoping to find a dynamic test to check the stator and trigger for output. The problem with a DVA is (according to a master electrician friend) is the response time is 500 milliseconds at best, too slow to see a pulse from the trigger or stator. A oscilloscope or analog volt meter may work better. Any input from a electronics wizard would be appreciated.

 

[rodbolt]

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

ya need to not listen to your master electrician friend, a DVA meter like a CD-77 or a DVM with the DVA adapter is what you need to test it with, its not a pulse type trigger.<br /> both the trigger and the stator give a rather slow analog signal.<br /> can be easily seen with a CD-77 on voltages as low as .5 peak.

 

[ColdFire]

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

Ok I am back at the beast. I have started over just to make sure. I have no spark on 1, 2 and 6(new positions since I swapped the boxes the first time around and then botched the test) the stator and trigger ohm out alright. If I swap the switch boxes the problem follows to 3, 4 and 5 (matches to the outputs in previous position if I am reading the schematic right). I have also found the red wire going to the idle stabilizer to be cracked so I am going to remove it from the circuit tomorrow night and try again (I had to put my helper and her little pony to bed ) . I am thinking that since the problem followed the switch boxes that they might both have problems. I tried making a DVA adpter that I found plans for and it seemed to show proper voltages from the stator and trigger, but my readings from the switch boxes were eradic so I might just have to break down and buy an appropriate adapter.

 

[MercFan]

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

Could this be a switch box or stator earthing problem guys?