Need Mercury Mech...

[Rock Man]

Man, I have big problem, have 86 merc. 90hp inline 6... used to fire up but not run, Now I have no spark or when I do it's not good or on all. replaced rectifier, stator, triger, fuel, had running a couple of times but ending is the same, fires up but won't run. Now it's worse, all six coils are reading good .02, compression is better then 120 on all cylinders, carbs been rebuilt(by mech), bypassed emergency shut off, even been trying to bypass key switch, the only thing else is the switch boxes but I never heard of two of these going bad... is this possible? What else could I check? or do? Please Help!!!

 

[omctech]

Re: Need Mercury Mech...

Switch boxes do go bad. However, it sounds like your motor has a short (grounded wire) in your system. Check continuity on all of your wires before trying new boxes.

 

[Hitman]

Re: Need Mercury Mech...

Check the motor harness that attaches to the switch boxes, I've had some with bare wires (orange w/black stripe) that crumbled apart and would not start, no spark.

 

[hondon]

Re: Need Mercury Mech...

Remove the ground wires from the switchboxes, triggers,and stator.Clean the connections as well as where they connect too, and see what happens.While your at it clean the battery terminals too.We may be looking at a bad bias circuit.

 

[Rock Man]

Re: Need Mercury Mech...

Thanks guys, My day has been spent checking every wire and cleaning all grounds that I could find. I think I got all of them, I even replaced the **** key switch with new one. "LOL" still same thing, I have spark on #4 at times and on others only when key is let go... that's why I changed switch, but right now when I just came in after all day on this thing. I have Nothing. my last try to fire, it did a little back fire thing, almost like it was out of time but I'm sure it was because of the firing problem... the only thing I see left is these switch boxes. Would hate to replace and still have same problem, been through that, Any other suggestions??? or could this be my problem? Is there any way to test these boxes??? and thanks again for the help!!!

 

[rlouns]

Re: Need Mercury Mech...

You may have already but incase you have not - take a good hard look at the kill switch. It could be intermittently causing the problem. I also had a broken wire that I could not find because it was broken under the protective rubber at the terminal end. That rubber held it in place and it would touch and work occassionally. When it finally fell out where I could see it I fixed it and no more problems. Just my 2 cents

 

[12Footer]

Re: Need Mercury Mech...

AHA,RobertL..So that's what it was? Glad you found it,man.<br />Rockman, are you saying that it seems to fire better, or have a hotter spark when you let go of the key?<br />If so, check the starter's current-drain and the battery. It may not be leaving you enough to energize the coils. Another way of checking this, is try (carefully) by a starter rope on the flywheel (if it has a pull rope option on the flywheel).<br />I would also check the timing belt (dunno about the 86,but the older models have a timing belt,that if it slips a cog, will not start for anything. This can be done by checking for top dead center by rotating the flywheel (by hand,ignition switched-off), and a pencil in #1 spark plug hole. If the TDC is off at all, that's the problem.<br /><br />Let us know what u find. Good luck.

 

[hondon]

Re: Need Mercury Mech...

Don't mean to keep flinging new and exciting crap at you ,but when that trigger and stator were changed,did anyone take a hard look at the flywheel magnets?

 

[Mikael-Block]

Re: Need Mercury Mech...

Hi all<br />I have a Marina 75 hp 4 cyl 1984.<br />I think it have a " mecury Switch " that kill the engine if I tilt it to high.<br />It might be hanging if it have been tiltet for a long time.<br /><br />Mikael Block

 

[Rock Man]

Re: Need Mercury Mech...

Hondon<br />Ya I checked Flywheel everytime I had her off, about 4 times, looks new, no cracks, and all magnets suck up screewdriver,<br /><br />12Footer <br />It does have better spark when let go of the key, but don't have belt, now you say check spark with pull rope?<br /><br />Mikael-Block <br />Ya the mercury switch!!! I thought it might be that, I toke wire off to by pass it, don't know how else to check this little thing (merc switch) any suggestions???

 

[12Footer]

Re: Need Mercury Mech...

Yes, if your flywheel has the groves in it for a starter rope, try to start it on the pull rope. It might be the starter drawing too much of what the battery has to start it. Or it might be a weak battery,not delivering enough power for the ignition,with the starter eating it all.<br />It could also be the switch,shorting out in start position.<br />You could start the motor at the starter solenoid, by jumping it (thus, ruling out switch problem in start position).

 

[Mikael-Block]

Re: Need Mercury Mech...

Rock man<br />If you demount the wire to the switch, it ok.<br />Mine only have one wire, shortned to ground if tilted to high<br />Mikael Block

 

[lakensea]

Re: Need Mercury Mech...

Don't bother trying to pull start it. The Mercury system does not use the battery for ignition. All it's power comes from the stator coils. The only way to correctly diagnose the system is with a peak reading voltage meter - paying a Merc tech to test it would have saved you a lot of money already. To check the stop circuit, disconect the black w/yellow stripe wire from the switchbox. That will isolate the mercury switch, kill switch and ignition switch. It is also the only place a short to ground will kill the ignition. Make sure the switchbox's are well grounded - a bad ground will kill them. Also, make sure that all plug wires are either hooked up to plugs, spark testers or grounded out when cranking. If the spark has no place to go, it can kill a switchbox. And it is not uncommon for both switchbox's to go - a bad one can kill the other one thru the bias connection. Before you go and spend $320 on a pair of switchbox's, I suggest you have a Merc tech check the ignition out with the proper equipment.

 

[singerjr]

Re: Need Mercury Mech...

Rock Man,<br /><br />This is not ment to insult in ANY way it's adviCe my farher gave me all his life. He's gone but I'll never forget it and I'm going to pass that advice on to you.<br /><br />BOY, DON'T BE PENNY WISE AND POUND FOOLISH!!!<br /><br />You have made a noble effort, I've done the same. I can't remember the last time I paid someone to work for me but I've done it and will do it again when it's pound foolish.<br /><br />Good Luck

 

[Rock Man]

Re: Need Mercury Mech...

Capt_Ultra <br />LOL, ya I understand that, I look at it as paid schooling... I sure understand my motor alot more now and know where every wire goes, but still don't have her running. Would like to find out problem, with the help of others of course, but it is at a certified outboard Mech. now, and he don't understand either!!! says it tests out good and should be running, but not! and he can't explain why it's not firing. I been going over to shop everyday working on this monster with him or by self. My luck will be I will have to take it to someone else if I or this so called Mech. can't fix. <br />Did take some R/R, caught me a Rock fish today and will be back on the boat work'n tomarrow. Sure would have been nice if I had her in the water.

 

[singerjr]

Re: Need Mercury Mech...

Rock Man,<br /><br />I enjoyed reading the entire thread, we all are learning from other peoples problems. There are some real sharp people here but it's tough you can't see it you can't get your hands in there on the PC so it is tough. And sometimes the advice you get here is "take it to a shop" and that's not because some of these guys couldn't fix it they just can't fix it over the internet. <br /><br />I think your at the balance point you are on the verge of spending too much on things you don't need. Take it to a cert. tech. let them bang their head against the wall figuring out what you need and pay the 65/hr or so and get back on the water. Money well spent. Hopefully you will get 30 days or so to check their work. <br /><br />You will be fat and happy on the water sooner rather than later doing what you do best because they did what they do best. You will be a little lighter in the wallet but if you keep going this way it could be worse. If it's a good shop you trust you will feel very secure in knowing the job was done right. <br /><br />There is no shame in saying "I've gone as far as my equiptment and knowledge will take me, I need help." <br /><br />Hey, good goin on that rock today, by the time you catch a few more your boat will be ready!!!<br /><br />Best of luck

 

[petryshyn]

Re: Need Mercury Mech...

Yo, Rock Man <br /><br />Just read your post. One thing that bothers me.......in your first post you say you bypassed the kill switch. Explain please....<br /><br /><br />(maybe we can lick this thing yet)

 

[DJ]

Re: Need Mercury Mech...

SChematic,<br /><br />That caught my attention too. Also, I find it curious that the spark goes away as soon as he lets the key go to the "RUN" position.<br /><br />I don't know anything about Merc's. but some of us probably remember that when old point fired cars did this, it was a bad ballast resistor.<br /><br />Does he possiblt have an open in his ignition switch?

 

[dmessy]

Re: Need Mercury Mech...

Rockman, if 1984 I-6 switchboxes will work on your 1986 and you find that you need them,give me an email. I'm parting out this 84 ,90Hp Merc. due to a broken lower end and I was on the boat when it went so I know they are good. Hope you get your problem solved.<br />dmessy@ev1.net

 

[smiley]

Re: Need Mercury Mech...

I tend to go with the switchboxes, Ive seen them do many strange things. change them both!