information 1978 90HP 6cyl

[scmillar]

Best plug for hot spark,will weak battery effect spark,and finally small vac line coming from top of engine to bottom side of power head behind<br />fuel pump,what is this line it falls off rather easily

 

[corm]

Re: information 1978 90HP 6cyl

Hi Miller,<br />Put a new recirculating hose on so you don't have any oil or vacume leaks. The std plug is best for all usage except strickly trolling. I don't remember when Merc switched ing sys but, if you have a dist on yours a bad battery will wreck your ing sys. If you don't have a dist you will only hurt your ele starter.

 

[scmillar]

Re: information 1978 90HP 6cyl

Thanks corm, I'll change the circulation line

 

[The Marine Doctor]

Re: information 1978 90HP 6cyl

Corm. I do no wish to correct you but I must.<br /><br />Its impairative to have atleast 12.6 volts constant or higher with Mercury or anyone's electronic ignition for that matter. If the voltage drops below the recommended voltage...damage to components can and will occur.<br /><br />TMD

 

[andrewkafp]

Re: information 1978 90HP 6cyl

I would have thought that once the motor is running, the alternator or (Stator/trigger/rectifier) on the coil pack motors would take over and provide the correct voltage. <br />That is why you have and optional pull starter on most outboards until they get too big to hand crank ???<br /> I'm no expert, but I've read the Clymer manual.. Maybe I've missed the point !!

 

[The Marine Doctor]

Re: information 1978 90HP 6cyl

If you have ever replaced an electrical part...there should be instructions that come along with them..Stating what I have posted above.<br /><br />I am not posting here to blow smoke up peoples butt's<br /><br />TMD

 

[what200]

Re: information 1978 90HP 6cyl

The spark on distributor mercs runs off the battery.<br />Use NKG BUHW plug. Do not use the champions 76v.

 

[andrewkafp]

Re: information 1978 90HP 6cyl

Millar<br />I'm not on here to sell you a battery or any components. So from my study of the Mercury manual,and a bit of experience, a run down battery is common with marine,as they sit around losing charge. Once the motor starts, it will begin to charge, whilst supplying the ignition with voltage at the same time. So, if your battery is less than 12v, as long as it can crank it will cause no damage. You may think about getting a small home trickle charger to keep it topped up though, as a battery kept in a charged state will last longer and be more reliable.<br />As for the plugs, stay with Mfrs recommended range or you may cause piston damage from too much heat.

 

[corm]

Re: information 1978 90HP 6cyl

Well everyone is right and everyone is wrong. It is impossible to have 12.6 volts when cranking to starter motor, unless your battery is the size of your boat and then you have a draft problem. Batteries at full charge only have 12.5 volts and under a cranking load can drop to 9.5 volts. If you have a CDI Thunderbolt ing sys, 9.5 volts is Death to your sys. With the ADI ing<br />sys it runs off the alternator of the motor so battery voltage is not as important as it does not run on battery volts like the CDI sys does. It has its own separate alternator coils that it runs on. A low battery with this sys is still hard on the charging sys and will wreck the starter + your nerves.(same goes for the CDI sys)<br />As far as sparkplugs go one brand is as good as the next (let the flames begin ) In the last 40 yrs I've used and sold them all (family business since 1954) I personally have found no real difference in them. So put in what the manufacture sent with the motor because that is what they got the best deal on. I use Champs because I like the name. I sell people what brand they want because I'm smart.<br /><br />The Marine Doctor is a knowlegable person, I've read his posts and know he hit the 6 instead of the 5 by mistake. He is right about the instructions in the ele packages. The companies do this for liability reasons. You have all seen the *no returns on ele products* sign. He is not blowing smoke.<br /><br />I have made poorly written posts on boards before and will again. So I am glad that others read them and correct them when wrong.<br /><br />btw, Unicorn & What200 do good too.