Spark plug question for Seahorse 20hp

dlivi04 · Jun 26, 2008

I am not sure of the year, but I have a hand driven 20 hp motor that just has the seahorse symbol on it. When I get it running it runs great but it wears me out with how many times I have to pull it to start. I currently have Autolite 303 plugs in it and want to change them. I have talked to people who have change their plugs and didn't have this problem anymore. Does champion make a plug that I can replace the Autolites with? Or is there another solution to why it would take so many pulls to start?

Joe Reeves · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

Look on the port transom bracket for a plate that will have the model and serial number on it. What is the model number?

Also on the powerhead, there may be a core plug (Looks like a small freeze out plug) with the model and serial number imprinted.

dlivi04 · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

Does E3419064 sound like one of those #'s?

dlivi04 · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

Having trouble finding Serial number or model number? Should I be inside the motor? Does S16604 sound like one of those 2?

CATransplant · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

Look all around the transom mount on that outboard for a label with the model number and serial number.

Bottom line is that it shouldn't be so hard to start. Does it run well at all speeds once you get it started? If it does, then it may be your starting routine that's not right. That engine should start in no more than three or four pulls when cold, and with one pull after the first start of the day.

Those 20hp engines should have Champion QL77JC4 plugs in them.

dlivi04 · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

I'll keep looking for the #'s. I run the motor very infrequently,but the last time I had it out we ran into the starting problems. Should I try and match up a champion plug with the autolite 303 and go ahead and change them out? If so, do you know the match?

CATransplant · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

The Champion plug, as I said, is QL77JC4.

It may be that new plugs will solve your problem. You should only use the recommended Champion plugs in that engine.

Just out of curiosity, can you describe the sequence of events you use when trying to start this outboard when it is cold? That could make all the difference.

dlivi04 · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

Thanks for the info.! I didn't see the last line about the sparkplugs on your first message.

When I am starting the motor I start by pumping the gas line from my tank. Then I usually pull the choke out before I pull the cord. The motor has a dial on it that says rich and something else but I don't ever mess with that.

Thanks again for your help!

ezeke · Jun 26, 2008

Re: Spark plug question for Seahorse 20hp

The serial number you gave fits the numbers from around 1971. I would continue to look for the model number which should be on a 1" X 3" aluminum plate on the port transom bracket.

CATransplant · Jun 27, 2008

Re: Spark plug question for Seahorse 20hp

Wow! I missed the earlier 20hp Johnsons. Those use a J4C plug, not the QL77JC4.

My error...sorry! The QL77JC4 has a 1/2" reach, while the J4C has a 3/8" reach. Don't use the previous suggestion in that older motor.

That'll teach me to wait for the model numbers to show up.

dlivi04 · Jun 27, 2008

Re: Spark plug question for Seahorse 20hp

How did my starting routine sound?

THANKS for for all your help guys! I am going to try the J4C. Like I said, I took out 2 Autolite 303's. Were those the wrong plugs or are the Champions just that much better for the motor?

ezeke · Jun 27, 2008

Re: Spark plug question for Seahorse 20hp

BRP is not listing any other plug besides the J4C for your motor at this time.

boatsetup.com doesn't either.

When you cold start your motor, put the choke on and keep it on until the engine fires. Keep the primer bulb fairly firm.

CATransplant · Jun 27, 2008

Re: Spark plug question for Seahorse 20hp

Your starting routine sounds OK. Be sure to put the shifter in neutral and open the throttle to at least the Start mark or just beyond that. I believe that your engine has a throttle limiter when in neutral. If so, open it as far as you can with the choke fully on. Once the engine fires, you can push the choke partway in until it's running smoothly. I normally let my outboard run a minute or two at the dock before setting out.

Sorry about the confusion with the plugs. Yes, Champion plugs are the ones recommended for your outboard. I wouldn't use any others.

Let us know how you do once you install the new plugs.

dlivi04 · Jun 27, 2008

Re: Spark plug question for Seahorse 20hp

I will, Thanks!

Spark plug question for Seahorse 20hp

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