1986- l-6 no fire 90/115

[country boy]

Hello, i just picked up on this deal on a 90/115 merc its a 86 model i believe
the lady i picked it up from said it ran ,and also said she knew nothing about boat motors!? well my problem is spin & spin no fire no kick or smoke looks like on any plug .geting gas every thing looks ok as far as i can tell so my thing is where to from here,where should i start,i have a complete running engine for parts but dont want to start changing parts to find the problem?any advice. compression is 120-130 on all cylenders.Thanks c.b.

 

[daveswaves]

Re: 1986- l-6 no fire 90/115

Hello, i just picked up on this deal on a 90/115 merc its a 86 model i believe
the lady i picked it up from said it ran ,and also said she knew nothing about boat motors!? well my problem is spin & spin no fire no kick or smoke looks like on any plug .geting gas every thing looks ok as far as i can tell so my thing is where to from here,where should i start,i have a complete running engine for parts but dont want to start changing parts to find the problem?any advice. compression is 120-130 on all cylenders.Thanks c.b.

Sounds like you have no spark, make sure your battery is fully charged, if not the inlines will not fire. Check the wiring for frayed insulation, they have a habit of rotting away.

 

[emckelvy]

Re: 1986- l-6 no fire 90/115

ADI systems are not dependent upon battery voltage except to have enough juice to make the starter spin.

ADI spark is killed by grounding the switchboxes so the first thing to do would be to disconnect the kill wire to each switchbox and see if spark comes back.

Kill wires are black with yellow stripe, if I recall. You can check with a meter by disconnecting both wires then with the meter on ohms scale, switch key off then on while measuring with one meter lead connected to one wire and the other meter lead to solid metal grounding point on the block. With the key "ON" you should have an infinite reading (no conection); with the key "OFF" you'll have a dead short (close to "zero" ohms).

Change the scale on the meter to DC volts and check for any voltage on the kill wires with ign switch both off and on. There should be no voltage, if there is it can kill the switchboxes. Usually if you find voltage at the kill wires it's a defective ign switch.

The trigger and stator can be resistance-checked once you fully disconnect their wires from the switchbox. Be sure to note where the wires all go; make a layup diagram so you won't get them mixed up between the 2 switchboxes. Each terminal on the switchbox does have a color marking, which will help.

If you eliminate the kill circuit, and the trigger and stator pass resistance checks, the switchboxes are the likely source of the problem. It's very unlikely to have all 6 ign coils fail. It's really not so common to have both switchboxes fail, either. So definitely you should check the other components carefully before spending a considerable amount on any particular part.

I prefer the CDI brand for ign parts replacement, they are reasonably priced and have never had one fail.

Here's some troubleshooting info you'll likely find useful:

http://dolphinmarineservice.homestead.com/ign5.html

http://www.boatpartstore.com/mercreadings.asp

You can search for ign parts here at the iBoats store.

I get my CDI parts here:

http://www.boatfix.com/searchcdi.asp

HTH............ed

 

[Goneflyin]

Re: 1986- l-6 no fire 90/115

Try unplugging the switch control harness from throttle assembly, a round multiwire vertical mounted plug by the middle carb and give a pull with a rope. Mine quit on me in the middle of the lake when it was fairly new (bad switch) but pulling the plug opened the short to ground as previous post mentioned. Be careful and pull the plug wires as the motor starts quite easily, done it numerous times.

 

[daveswaves]

Re: 1986- l-6 no fire 90/115

Sounds like you have no spark, make sure your battery is fully charged, if not the inlines will not fire. Check the wiring for frayed insulation, they have a habit of rotting away.

I was half asleep when I answered this, Ed's got the answer, thanks Ed.

 

[country boy]

Re: 1986- l-6 no fire 90/115

Thanks,Ed/all this is some really helpfull info.sounds a lot of experience in there.looks like i have some checking to do,i will start with the control box /stator/triger/switch boxes.process of elimination i think it will run if i could get fire to her.I will re-post progress,Thanks CB

 

[country boy]

Re: 1986- l-6 no fire 90/115

Hello!update on issue checked kill switch (ok) checked stator (ok) checked triger(ok) disconected rectifier and still no fire had no way to check power packs .they were the only thing did not pass inspection.so i had a set off an old running motor i had some time back,and now i got fire (2 bad power packs) fired her up and runs like it should (great actually) 120-130 psi i am extremely happy thanks for the advise everyone this forum is very helpful.

 

[emckelvy]

Re: 1986- l-6 no fire 90/115

Most likely one power pack went bad and then took the other one out. I hear the CDI replacement packs aren't as prone to doing this.

Glad you got it running, congrats you've just learned troubleshooting skills good for many other motors, anything past 1980 or so (and some earlier models) are using one variant or the other of the ADI system!