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1971 Mercury 7.5 hp

T

tmise

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Just recently bought a 1971 Mercury Comet 7.5hp to use as a kicker motor. Wasn't getting spark to the No. 1 plug so I had to replace the bad wiring coming from the points. Getting spark to No.2 plug. I swapped the wire coming from the No.1 points to the No.2 coil and get spark. I removed the green jumper wire from between both coils, it was frayed, insulation falling off, etc...Made up a new jumper wire with 12 gauge wire, still no spark at No.1 plug. But if I remove the green wire coming from the stator to the No.2 coil and hook it up to the No.1 coil, I get spark at the No.1 plug. So this tells me the coils are good, am getting juice from the points and getting juice from the stator. Why is it when I hook up the jumper wire between the two coils I can't get fire to the No.1 plug? Is it possible the new jumper at 12 gauge is too much and maybe I should go to a smaller gauge? I used this gauge wire to replace wires coming from the points also as I couldn't find anywhere as to what gauge to use.
 
That's easily enough wire size--the CDI stator use smaller than that.

Got confused by your explanation, but here's the deal on those infamous Phase Makers: Anything that can go wrong, already has! (Yeah: I hate those SOBs!)

I suggest that you have one bad coil and it's causing you a bunch of weird trouble. You can buy a good used coil on eBay cheaply. I would buy one and replace each coil, one at a time, 'til you isolate the problem.

Jeff

PS: WHen I get REALLY ticked with a P M, I replace the whole stupid thing with a Phelon magneto! Done that a couple of times now.
 
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fastjeff said:
That's easily enough wire size--the CDI stator use smaller than that.

Got confused by your explanation, but here's the deal on those infamous Phase Makers: Anything that can go wrong, already has! (Yeah: I hate those SOBs!)

I suggest that you have one bad coil and it's causing you a bunch of weird trouble. You can buy a good used coil on eBay cheaply. I would buy one and replace each coil, one at a time, 'til you isolate the problem.

Jeff

PS: WHen I get REALLY ticked with a P M, I replace the whole stupid thing with a Phelon magneto! Done that a couple of times now.
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Thanks for the reply yeah thought it sounded alittle confusing too. The coil that the green wire goes to from the stator works. The other coil does not work unless I take that same green wire and attach it to it, then I get spark from that coil also. But when I put the green wire back on the No.2 coil and attach a jumper from it to the No.1 coil, no juice to No.1 plug. The jumper wire that was on the engine was corroded etc...so I made up a brand new one. Don't understand why I can't get spark with the jumper attached??
 
kimcrwbr1 said:
There is a ground wire on the bottom of the coils also. Pull the coils and swap them and lightly sand the base of the coil mounts and rough up the braided wires on the bottom of the coils. If you have the same problem then both coils are good as long as you get around 3/8 inch spark with a spark gap tester. The phazemaker system is one of those combo CDI type with a points trigger not one of mercs finest moments. Be sure and use a spark gap tester anything less than 1/4 inch is unacceptable.
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Thanks for your reply. On this engine that short bare ground wire is on the top of the coil. It just lies on top of a rubber piece that fits over half of the coil? Then the metal coil cover goes over that. Still don't see how it can make good ground that way. I doubled over the ground wire to make it thicker to see if that would help. Going to order a spark gap tester in the mean time to see how strong or weak it is. But as I said before I don't understand why I can't get spark with the green jumper wire attached from one coil to the other? Doesn't make sense.
 
Really would like to not modify this outboard at all. Had been sitting for 15 years and looks to be in real good shape from what I can tell. Found green wire coming from stator was partially broken. Spliced 12 gauge into that and will adjust the points tomorrow. From what I could tell they did not seem to be opening to .020". So tomorrow I am going to sand the points clean and try to adjust them. Paid just $200 for this engine so I'm ok with putting alittle money into it but not too much.
 
No just used a regular spark plug tester that has the bulb inside. Just ordered a gap tester to check it with that. So far I've found coils for $72 each and a stator for $300 if I need them as I don't know yet. Going to adjust and clean the points today. The white insulator blocks look to be in good shape. This has the Thunderbolt ignition not sure exactly what that means. This engine has stator with two wires one green(to No.2 coil) and one salmon(kill switch). Two points white wire to No.1 coil and brown to No.2 coil. Thats pretty much it, don't see any condensor or anything like that.
 
Thanks for posting that stator link for me, that seems like a decent price! Like I said I don't mind pumping some money into it since it only cost me $200 and the engine looks practically brand new I think it's got some good life left in it and heard they are good engines.
 
Yeah this one holds oil. That was the first thing I did when I got it home was change the lower unit oil and then the impeller. Was going to ask you, the white wire and brown wire coming from the points was corroded and the insulation was falling off so I cut these close to the white plastic insulators and spliced new 12 gauge into it. Thing is the wire I used is thicker gauge, what gauge are those wires? Couldn't find that info anywhere so just gambled it was 12 and ordered that. Probably is 14 or 16 gauge I'm guessing. Does it matter that I spliced a bigger gauge into a smaller one? Or should I order the right size and take it all the way to the white insulators instead of splicing it? Thanks
 
Ok here is what I did. I swapped the points wires going to the coils and got spark to the No.1 plug! So something is up with the No.1 points, wire or white plastic insulator! Points don't look to be in great shape by any means so I'm going to start with new points and go from there. I had removed that white insulator before when I had to splice in a new wire and it looked fine, no cracks or arching marks nothing like that. Anyone know where I could get a set of points at a decent price?
 
Anybody know where I could get a set of points for a 1971 Mercury 7.5 hp serial #3103879 for a decent price? Only ones I'm finding are for around $100 plus. Thanks!
 
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