115 johnson no power

[flech01]

Hello all and thanks in advance for you help.<br /><br />I have a 115hp johnson 1976 on a 17ft sunbird.<br />This motor takes forever to get on a plane and just seams to have no power what so ever. Here is a list of this I have already checked.<br /><br />Carbs- Just rebuilt<br />Fuel- New bulb and container <br />Prop- I have 4 props and hardly no change.<br />FuelPump- have tryed two types high performance and just the regular type and no change.<br />Coils- Replaced all four.<br /><br />The motor sounds like it hits full boar but does not move like it is. <br /><br />When I turn sharp corners the motor reves up real hi like it is cavatating. I have played a little with the placement of the motor but can that little of an adjustment affect the top speed and make me get out of the hole and on to a plane. <br /><br />Top speed as of right now is about 33mph.<br /><br />Compression is about 115 in 1,3,4 and about 100 in number 2. Could this be what is going on?<br /><br />Thanks again and sorry for the long post.

 

[angus63]

Re: 115 johnson no power

Check that spark can jump a 7/16 gap strong on each cylinder and then verify sync and link settings for carbs and timing. I would also try an alternate fuel supply to rule out fuel condition. If all this doesn't help, then I would start checking all of the ignition components per the manual.<br />Good luck

 

[OBJ]

Re: 115 johnson no power

The link & sync syncs the timing with the carb throttle plates. Follow the instructions in the service manual.<br /><br />Couple questions while I got ya' captive.<br /><br />What is your WOT rpm?<br />Do you understand the use of the trim and tilt if you have it?<br />Where is the anti-cavitation plate (plate right over prop) in relationship to the keel of the boat..above, below?

 

[dolluper]

Re: 115 johnson no power

placement of your motor is very important it sounds as if in fact you are to high up on your transom ,link and sync is when your trottle plates open together equally and close together equally adjusted by linkage between the carbs right side [starboard] when your looking at the bow I am assuming your bottom end is Full of oil and clean not milky coloured

 

[flech01]

Re: 115 johnson no power

I have tryed alternate fuel systems and none have helped. I Have a manuel and I am looking into the link and synk but im not to familiar with that if anybody has any advice on how to link and synk it would be greatky appreashed.

 

[flech01]

Re: 115 johnson no power

Is the link and synk the synking together of the two carbs ie choak butterflies or rear butterflies? Or is it the synk between the carbs and motor?

 

[dolluper]

Re: 115 johnson no power

forgot to say you have to check your timing with timing light on #1 cyl start hear up and turn your idle speed screw till you get 5 degress advance got that done shut her down then open throttle to wide open it should hit the stop now adjust the throttle adjust screw so you have .003 between the pin and the stop [full throttle screw located bottom of pivot arm upper other side of your arm is idle screw]

 

[flech01]

Re: 115 johnson no power

Obj I don't have a working rpm guage i am in the market to get one but I don't know what or where to get it from or what type to buy. Is there a special one I have to get for my Johnson?<br /><br />As for the anti-cavitation plate it is above the keel. I have tryed the trim tilt and mabe got some more speed at the top end but no help with take off.

 

[flech01]

Re: 115 johnson no power

Thanks dolluper I will check all of that stuff tonight. Oh can I time it out of the water or should i time it at the lake?

 

[dolluper]

Re: 115 johnson no power

it's done at idle but you need water with muffs on or in the lake don't want to cook anything

 

[flech01]

Re: 115 johnson no power

Is the anti-cavitation plate supposed to be below the keel?

 

[angus63]

Re: 115 johnson no power

even or just above. Alot depends on prop and hull design.

 

[Solittle]

Re: 115 johnson no power

The best location for the cavitation plate will vary from boat to boat. The place to start is even with or 1/2" or so above the bottom.<br /><br />Did you do the spark check that angus recommended? <br /><br />What is the pitch of the prop that is on the boat?<br /><br />You will need a working tach to really nail this.

 

[OBJ]

Re: 115 johnson no power

SoLittle is on the money with the tach. You need to see what the engine is turning. Anything you do now is just a shot in the dark. Tachs can be bought through your local John/Rude dealer or right here at iboats Mega Mall. Check them out.

 

[flech01]

Re: 115 johnson no power

What one do I buy? do I have to buy a special one for the type motor I have?

 

[flech01]

Re: 115 johnson no power

The pitch prop is 19 I have a 16 pitch but it is worse than the 19 pitch.

 

[OBJ]

Re: 115 johnson no power

Most Bomby tachs are "plug and play" meaning nothing special to do to get it hooked up. Some Teleflex tachs may need a resistor added. Bomby Tachs are a little more money. If your control box doesn't have a tach plug which would be right above where the cables enter the control box, you may have to run some wire. On John/Rude harness', the gray wire is the tach lead or signal wire. All that you then need is a 12V source, usually off the ignition switch and a ground.

 

[Solittle]

Re: 115 johnson no power

Bill - Check Tiny Tach in the red search at the top of the page.

 

[flech01]

Re: 115 johnson no power

Ok if the control box doesn't have a quick connect. Will the Tach have directions on how to hook it up? I have a manuel will that tell me how?

 

[angus63]

Re: 115 johnson no power

Tach needs 12V positive, ground, and sender from rectifier to work. 12v pos and ground can be taken from any source on the dash that powers up when the key is turned on. Not sure about 1976 motor, but commonly a gray wire from the rectifier is the sender signal for the tach. There also may be a fourth connection for a light that can be tied in to your running lights. The tach will have directions and usually the connections are identified on the back of the gage. Be sure the tach is able to accept a 6 pulse signal.<br />Good Luck<br />Good luck