I've always used standard spark plugs which cost around $2-$3. Then someone said that I should use resistor spark plugs if I have electronics on my boat such as trolling motor and fish locator. I have both. The resistor spark plugs cost $7.49 each. Yikes!

 

 

This is what NGK says about resistor spark plugs:

 

 

When should I use a resistor spark plug?

 

A: NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking.

NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance. This is because resistor spark plugs reduce electromagnetic interference with on-board electronics.

They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer.

In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion.

 

 

 

I haven't had any problems since I first started using motors however, at the end of last season my motor was having a rough time starting. The spark plugs were new that year. One guy I know changes spark plugs twice a year, but I've always done it every 2 years. Maybe the rough starting was the spark plugs.

 

 

 

 

So, do I need to use resistor spark plugs?

 

 

 

And how often do you change spark plugs?

What does your manufacturer say?  Do their motors come with resistor type plugs?

 

In some cases, they are necessary.  Years ago, fifty or so, before electronics even approached the sophisticated gizmos of today, resistor plugs were fairly common.  They helped to reduce ignition static in the old am radio receivers.

 

Even then a majority of vehicles did just fine without resistors or suppressers.

 

I suspect that today's electronics come with a certain degree of "noise filters" in their circuitry.

 

Further, most of the time, you are on the trolling motor, not the propulsion engine, so the spark plugs serve no useful purpose when you are on the trolling motor.

 

Difficulty starting can be caused by a number of things.  For an engine to run, it needs fuel, air, and ignition.  You could have contaminated fuel.  You could have a clogged filter(s).  Your plugs could need changing.  It could be in the fuel delivery system, such as an air leak in the fuel line between the tank and the engine.

 

You could replace components one by one until you solve the problem.  Or, you could take it to a technician who will, for a fee, plug it into a computer diagnostic device to find the problem. 

What does your manufacturer say?  Do their motors come with resistor type plugs?

 

In some cases, they are necessary.  Years ago, fifty or so, before electronics even approached the sophisticated gizmos of today, resistor plugs were fairly common.  They helped to reduce ignition static in the old am radio receivers.

 

Even then a majority of vehicles did just fine without resistors or suppressers.

 

I suspect that today's electronics come with a certain degree of "noise filters" in their circuitry.

 

Further, most of the time, you are on the trolling motor, not the propulsion engine, so the spark plugs serve no useful purpose when you are on the trolling motor.

 

Difficulty starting can be caused by a number of things.  For an engine to run, it needs fuel, air, and ignition.  You could have contaminated fuel.  You could have a clogged filter(s).  Your plugs could need changing.  It could be in the fuel delivery system, such as an air leak in the fuel line between the tank and the engine.

 

You could replace components one by one until you solve the problem.  Or, you could take it to a technician who will, for a fee, plug it into a computer diagnostic device to find the problem. 

 

 

 

Where would I find what the manufacturer recommends?

 

 

I have a 2000 Mercury 115 horse.

Try a google search, or call a Mercury dealer and ask them what plugs they recommend for your motor.

It says both.....so can I just use the cheaper non-resistor ones?

 

 

 

Also,....is this an EFI motor?

 

 

 

 

 

 

 

Use the cheaper ones. If you have a problem with noise change them.....