john 3hp won't start

[rgeddes]

I have a 55 johnson 3 hp motor. I replaced the points and plugs. It has good spark. I had a problem with the carb, but it started a few times by spraying carb fluid into the carb. I bought a new carb and rebuilt it. I won't start. I checked the cylinder and its getting gas, but just won't start. Even when i spray carb fluid. Any suggestions?

 

[Rick.]

Re: john 3hp won't start

First thing I would do is check your compression. Did you set your needles correctly after carb. rebuild? Did you clean the carb. really well? You say it fired at one point so that is a good sign. Get back to us. Best of luck. Rick.

 

[boobie]

Re: john 3hp won't start

When say you checked the spark, will it jump a 1/4 " open air gap on a spark tester ??

 

[rgeddes]

Re: john 3hp won't start

What do you mean by ajusting the needles and how do I do that?

 

[Rick.]

Re: john 3hp won't start

http://forums.iboats.com/engine-fre...sorted-carb-variations-joe-reeves-167352.html
It is well explained here. If they aren't open you won't be getting gas. Just to prove gas flow from the tank you could open a fitting below the fuel valve to see if you have flow but the needles first. Rick.

 

[rgeddes]

Re: john 3hp won't start

Thank you for the link. It was helpful. I adjusted the needles. I re-checked the spark. It was not consistent. The wires are rusted and cracked. I will try replacing the wires.

 

[Rick.]

Re: john 3hp won't start

How did the coils look? If the wires are shot I would expect the coils are too. Did you clean and adjust the points? Your problem has gone from fuel at first thought to spark. For spark I would suggest taking the flywheel off and having a good go at the magneto. Rick.

 

[kfa4303]

Re: john 3hp won't start

Here's a handy link that can walk you through a tune up from top to bottom.

3 HP Evinrude Johnson Outboard Tune-Up Procedure 1952-1967

 

[maak]

Re: john 3hp won't start

I know this isn't the same motor & I hate jumping in, but would there be a site like this for a 1971 2 HP Johnson??? I just picked one up today & I'm looking to get it set up for when the ice is finally off the lakes... It ran very nice during the sale, but I'd like to get to "know" the motor before taking it out on the water... Thanks for all the info on this site... I've been on it for hours.... LOL

 

[jbjennings]

Re: john 3hp won't start

A 2hp and 3hp which you mentioned have the following things in common: hey both have the same ignition systems, both need good compression to run properly, and clean carbs. If you take care of that, it'll be a good runner.
SOme things mentioned in this thread that I think were good advice for both motors: check spark with a spark tester---it's one of the first things that a person that owns any kind of gas engines should own (about $10 at a auto parts store). Tune the carburetor properly (link shown in previous post). Check the compression (also about $30 at an auto parts store---they're notorious for being inaccurate so look for a difference between cylinders).

BTW: I've heard that a lot of the older 3hp were used for so many years and run hard that some of them are just plain worn out. I'd definitely check the compression. I have a '67 3hp ducktwin that I got recently that has 90psi in both cylinders, which I thought was really rare. I'd have been pleased it it had 80psi in both. I personally don't think a 3hp would run and idle good with less than about 60-65psi.
JMO,.
JBJ