72 40hp Johnson.2 questions

[Saboat]

1.Starts and idles fine.Will run to about 1/4 throttle if edged slowly,and die immediately if accelerated hard.Pulled choke lever when accelerating and runs fine ? Can't see or find any air leaks on lines,could float level cause this ?<br />2.Should there be sign of battery charging at idle or does the charging system only kick in at higher revs ?<br /><br />Thanks in advance

 

[BoatBuoy]

Re: 72 40hp Johnson.2 questions

1. When my 35 did the same, I had trash (water) in float bowl. Pulled drain screw and tilted forward to drain. After that, it ran fine.<br /><br />2. Don't know.<br /><br />Other folks may advise to do a carb job and that's OK too. This is only what fixed mine.

 

[Paul Moir]

Re: 72 40hp Johnson.2 questions

1) I agree with BoatBuoy. Time to clean out the carb.<br />2) If your engine is equipped with a generator, it will not start charging until the engine is up over 1000RPMS or so. If it has no generator, it will not charge the battery. The generator is about the size of the electric starter, and is mounted on the other side of the carburetor. it is connected to the flywheel by a toothed belt.

 

[Saboat]

Re: 72 40hp Johnson.2 questions

Thanks guys.I pulled the carb apart and cleaned it.Did see some small black grit in the float bowl.Also found a heap of junk behind the metal sieve filter on the fuel pump.Will run it on the week-end to test.<br />The motor definitely has no "alternator" but I thought the coil assembly under the flywheel might generate charge to the battery?

 

[OBJ]

Re: 72 40hp Johnson.2 questions

That's just the charge coil Saboat. Set's up the charge for the points. <br /><br />On your model, there would be a bracket with a belt driven generator as Paul pointed out.

 

[Saboat]

Re: 72 40hp Johnson.2 questions

Sorry Paul,I didn't notice anything that looked like it would accomodate a bracket let alone a generator on that side of the motor.I'm gonna have to look for one.Would the belt connect to the teeth around the centre piece of the flywheel ? it doesn't seem like anything would stop it from slipping off.

 

[Paul Moir]

Re: 72 40hp Johnson.2 questions

If you look higher up on the flywheel, you'll see a square toothed portion. That forms the pulley for the generator's belt. The generator's pulley has shoulders to keep the belt in alignment.<br />There are three components to the charging system - the generator itself, the generator bracket, and the regulator. There's a few posts here about using an automotive regulator for the generator if you can't get a hold of it. <br />The generator is not really that great. It puts out 10 Amps max (120W), and only does that at full throttle.