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Discussion Starter · #1 ·
I went to Steven's marine and bought new plugs today. When I was taking the old ones out I noticed that they were resistor plugs. The ones I was sold were not. Same part number, just the ones I have are minus the "z" which I guess denotes resistor. I called back and spoke to the person who sold them to me and he said there was a 90% chance they would work fine and were about 1/3 the price of resistor plugs. When I asked him if it would cause any damage if they were not fine he said, no, the motor would just run bad. He said I could take it out and run it and if they didn't work I could still exchange them.
So, I am a little nervous about running them and causing damage so I went to look in my owners manual to see if there was a huge warning saying "USE ONLY RESISTOR PLUGS OR YOUR MOTOR WILL BLOW UP" but I can't find my dang manual. So I went to the merc website and went to the parts order page to see what it specified for my motor. It had me put in my serial number and listed all the parts for my specific engine. Well, now I'm even more confused because it listed 3 different plugs for my motor. What's the deal? This is supposed to be specific to my engine. Is it owners choice on which plugs to put in it?
So basically my questions are will it do any damage to run these plugs? Why are resistor plugs needed? And why is there 3 plugs listed for my motor? Someone please help, this is driving me nuts. Oh, my motor is a 2000 50hp if anyone has a manual and can look it up that would be great too.
 

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Rimshot: Were the plugs you removed painted black? Are you sure the motor is 2000? Is it a 2 Stroke motor?

1991-2000 50HP Merc (3Cyl) call for BP8H-N-10

2001-present 50HP Merc (3cyl) call for BPZ8H-N-10

I am told be a longtime Merc mechanic friend that it shouldn't hurt anything. It might affect your radio reception in the boat and other electronics by not having a Resistor plug.

The Serial Number plate will also indicate the Model year.

Call 4 Season's Marine in Medford 541-665-2920 and speak with Tim (the Owner). He's honest and has no reason to steer you wrong if you have any further questions. :grin:
 

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Discussion Starter · #3 ·
Yes they were painted black. How did you know that? Yes, I'm sure it's a 2000. Yes, it is a 2 stroke. So, I should be ok huh?
 

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I had my friend Tim (4 Season's Marine) look it up. The fact that they were black just means they were original. Tim seemed to think it doesn't matter. If you have any weird stuff with electronic reception I'd put the Resistor plugs back in. Otherwise, go with the less expensive ones.
 

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Discussion Starter · #5 ·
RogueFisher,
Thanks you very much for your replies. They put my mind at ease and I'm gonna go run her tomorrow and see how things are. I just wanted to make sure I wouldn't cause any permanent damage. By the way, he didn't happen to say what the gap should be did he? The guy at the shop said they are pre-gapped but they he threw them in the bottom of a sack and then put my oil on top of them. I would like to check the gap to make sure it is correct on all 3. Again, I can't find my manual. :depressed: . Anyone know what the gap should be? Thanks again RogueFisher :smile: .

[ 07-02-2003, 07:45 PM: Message edited by: Rimshot ]
 

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both my motors call for a .040 gap. One is 1996 Merc 115 and the other is a 2000 8 H.P. both are 2 strokes.

There is a good chance that your motor requires the same gap.
 

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In auto plugs a resister plug and a non resister plug are basicly the same eccept The resister plug helps with electical noise on your radidi-o and tape player with the new computer ignitions if it calls for resister plugs you better use them because there is a chance that non res. plugs could cause the computer to do wierd things. On an outboard don't have a clue.
DAB
 

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Rimshot,

All that resistor plugs do is to help reduce electrical noise that is induced on your boat's electrical system. Do you have a VHF or AM/FM radio on board? This electrical noise can be heard as a buzzing sound on your radio that increases in pitch when you rev your engine.

Try the regular plugs. Your motor will be fine but your radios might whine a little bit.

You should be able to download an owner's manual from the manufacturer to get the plug gap. Its true that the plugs are pregapped but sometimes they are off by .001-.002 or so. I always check mine to be sure.

I would guess the 3 different part numbers may just be equivalent part numbers by other plug manufacturers like Champion or NGK.

I'm surprised that Mercury would splurge on resistor plugs for your motor. I have a 2000 115 hp and a 2000 15 hp and Mercury never put them in mine.

Good luck :smile:
 

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If noise is a problem with your new plugs, a resistor can be placed in the power supply line of your radios, available at best buy, or any car stereo store. likely cheaper than the price difference with the plugs.
 

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In doing a search for info on my older kicker motor, I ran across a website for boat motors which also includes a BB. Some questions may be answered there. You can also order owner's manuals and repair manuals from this site.

Iboats Bulletin Board
Boatmotors.com

Hope this helps.

Steve :cheers:
 
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