Johnson 15 hp

[Riverrat47274]

I'm have problems getting my 15hp to start.just rebuilt carb and put new fuel pump on.also installed new plugs.seems to not be getting gas to cylinders but not sure.any ideas?

 

[boobie]

Re: Johnson 15 hp

Got a model # ???

 

[Riverrat47274]

Re: Johnson 15 hp

J15rtca.1983 Johnson 15hp.i soaked carb in carb cleaner over night and blew out all passage ways with air.replaced float,needle and seat plus gaskets.set slow speed idle 1 1/2 turns out from light bottom out.getting gas to carb.but won't fire up.

 

[Jim Hawkins]

Re: Johnson 15 hp

did you try squirting a little fuel into each cylinder to see if it fires?

 

[tomhath]

Re: Johnson 15 hp

Do you have a spark? Pull both plugs but reconnect the wires, then touch one at a time to the block while you spin the motor. You should see the spark jump across the electrode. Lots of good information here:

Maintaining Johnson 9.9 Troubleshooting

 

[Riverrat47274]

Re: Johnson 15 hp

Coils are good,have spark.will fire up if manually put gas in cylinders.

 

[boobie]

Re: Johnson 15 hp

What's the compression on it ??

 

[Riverrat47274]

Re: Johnson 15 hp

Have not tested compression.motor ran before work but had a dead spot in carb like it was sucking a piece of dirt or something up onto the main jet.it would do this periodically and sometimes would run right when increasing throttle.so decided to rebuild carb.

 

[Jim Hawkins]

Re: Johnson 15 hp

I think you just missed something in the carb cleaning. I've cleaned carbs 2 and 3 times before getting them right. Anymore I usually dunk them, blow them out, wash with hot water and dishsoap, rinse, blow and dunk them again...

 

[Riverrat47274]

Re: Johnson 15 hp

When I cleaned carb I soaked over night in carb cleaner and in the morning I blew out all passages and jets with compressed air.done this for 3 days in a row(waiting on carb rebuild kit) the only thing I did not do was remove welch plug and lead shot.just soaked carb then blew these passages out with air.

 

[Tom Maslar]

Re: Johnson 15 hp

do the welch plug and then give it a topcoat of rtv. also, dont forget to make sure it seats properly. You can give the edges a light coat of vaseline on installation. make sure vent is not plugged. this may sound crazy, but I have had great success cleaning carbs with 3 in 1 oil and compressed air in a can. it dissolves the worst gunk in a carb. I dont like carb cleaner. Its nasty stuff and in my opinion does not clean very well --but you should make your own decision on that--check that you have all your lead shot and that it is not sucking air too.

 

[Tom Maslar]

Re: Johnson 15 hp

btw, did you replace the needle packing washers?

 

[Riverrat47274]

Re: Johnson 15 hp

Yes replaced needle seat washer and idle screw washer

 

[Riverrat47274]

Re: Johnson 15 hp

Just wanted to say thanks for all the advice.will have to go back and check carb.also if idle screw is not set right would that cause motor not to start?

 

[Cofe]

Re: Johnson 15 hp

Couple of things to check cross my mind. Verify that the arrow on the primer bulb is pointed towards the motor and all fuel line connections are tight. Also if you can, borrow another tank and fuel line to make sure there is not a fuel delivery problem.

 

[bonzoscott]

Re: Johnson 15 hp

Did that model have the cork float? Was the varnish flaking off? If so, the carb may need cleaned again. New BRP float will be plastic. Go to Shop2 Evinrude or Marine Engine (& others), look up your motor and carb, then verify you have accounted for all parts. It's easy to leave something out.

 

[Daviet]

Re: Johnson 15 hp

The low speed needle should be set 1 1/4 turn out from lightly seated for the engine to start, you will have to fine tune it in the water with the engine in gear. There are passages under the core plug on top of the carb that have to be clean, if you didn't remove the core plug when you cleaned the carb you might want to remove the core plug and check the passages.

 

[Tom Maslar]

Re: Johnson 15 hp

Buy yourself a "coast" flashlight that attaches to your waist belt. You will find it to be an indispensible tool as you work on the motor--especially the carb. You will be amazed at the difference it makes--trust me. I also make sure to use reading glasses but you may not need those! Go for a light with the higghest lumen number--you wont regret it.

 

[Riverrat47274]

Re: Johnson 15 hp

Hey guys went back and recleaned card,found some gunk in it.reinstalled carb and she fired right up.now just have to fine tune.thanks for all the help!!!

 

[Daviet]

Re: Johnson 15 hp

Glad you found your problem and got your engine running properly.