Need help, have 73 Merc Thunderbolt 850(85hp) and it won't start. NO spark. ideas?

[jpgsr2001]

I need help Have a 73 Merc Thunderbolt 850(85hp) and it won't start. Any ideas? Any idea where i can download a manual please? I am not getting spak at the plugs? I am New to boat motors though. Any idea where i can download a manual please? Thanks in advance!!

 

[skey]

check power to coils and then from coils. if none to coils try power in and out of switch.

 

[jpgsr2001]

check power to coils and then from coils. if none to coils try power in and out of switch.

Not sure HOW to do that, Hoping to get a manual or diagrams to help me determine if its coil, Distributer, trigger, Power pack? (the last two are things I know NOTHING about them on youtube something about them?) I am ASSUMING it is the coil? are there more than one? I only see ONE wire going from the cap to the coil? Any idea on WHERE I can get more info on this motor? Diagrams, Manual, ANYTHING? Of course, I have NO manual,..THANKS SO MUCH for ANY help I can get. I am a Newbie to working on boats but I have worked on cars for years so I no completely blind here...

 

[jpgsr2001]

check power to coils and then from coils. if none to coils try power in and out of switch.

Sorry, is the "switch" you refer to the plate with like three wires on each side above the carb? It looks kind of like a "terminal block"?

 

[skey]

Sorry, is the "switch" you refer to the plate with like three wires on each side above the carb? It looks kind of like a "terminal block"?

I was referring to the ignition switch

 

[jpgsr2001]

Ok. Thank-YOU! It IS turning over, just not starting..

 

[skey]

don't make things hard. you have mechanical background. think of it the same way. power comes from battery first, to ignition switch an so on. you have to have power going in to get it out. get a meter and chase the power and find where it stops.

 

[skey]

I haven't dealt with a 73. but follow your plug wires back to the coils how many are there 3??

 

[jpgsr2001]

I only see ONE coils, but the motor is a FOUR Cylinder.. There is only one wire that goes into the center of the cap so I assume it only has ONE coil? That's what it looks like. Wish I had a manual for this, damn.. Thanks for trying to help me but I am going to have to keep looking for a manual...

 

[jpgsr2001]

I haven't dealt with a 73. but follow your plug wires back to the coils how many are there 3??

Thank-YOU! I will chase it out more. I think it is the coils so I am going to try to find more info and take it from there. Thanks!

 

[Chris1956]

The Mercury coils rarely fail on those motors. Inspect the wiring harness. Most of the originals will be bad.

Your ignition system is driven by the battery. You need to have +12VDC on the red wire on the switchbox, as well as the white wire next to it. Red will be "hot" all the time. The white will get "hot" when the ign key is set to start or run.

CDI Electronics has a troubleshooting guide for your motor. Look on their web page.

 

[jpgsr2001]

Thank-YOU Chris! I will check their website and test the voltage. It IS turning over real well so the battery seems good and fully charged, but i will check those terminals and the website! Thank-YOU!