1958 18hp Johnson hesitating and lacking power

[restornator]

Here's the motor: http://www.youtube.com/watch?v=P5QsYSCKt98

The carburetor is clean, new gaskets, float, needle, check that off. Ignition has all-new components. My concerns are fuel pump and compression. The motor just doesn't want to rev up

Here's my 56' 15 hp that runs great, just needs a kill switch: http://www.youtube.com/watch?v=p0-06oBzP1s

 

[tashasdaddy]

Re: 1958 18hp Johnson hesitating and lacking power

good stuff here (carb adjustments) http://forums.iboats.com/showthread.php?t=299680, did you replace fuel lines. also check spark, acted like it was running on one cylinder.

 

[MudLake]

Re: 1958 18hp Johnson hesitating and lacking power

Here's the motor: http://www.youtube.com/watch?v=P5QsYSCKt98

The carburetor is clean, new gaskets, float, needle, check that off. Ignition has all-new components. My concerns are fuel pump and compression. The motor just doesn't want to rev up

Here's my 56' 15 hp that runs great, just needs a kill switch: http://www.youtube.com/watch?v=p0-06oBzP1s

As funny as my story may sound, it is true!!!!!!!!!!!!!!!

When I first got my boat and twin 1961 johnsons last summer I went over each motor and replaced and cleaned everything that was dirty or cracked as in coils ect.

I put each outboard in a 45 gallon drum of water. Fired each unit up to test. They both would idle all day but would not rev past half throttle.

I concluded because they smoked so much they were trying to burn their own exhaust and thus would be runing too rich.

I used a fan to blow the fumes away from the barrel and all way well.

Put them both on the boat and headed for the rideau river where they run perfectly.

Hope your issue can be this simple

cheers

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

good stuff here (carb adjustments) http://forums.iboats.com/showthread.php?t=299680, did you replace fuel lines. also check spark, acted like it was running on one cylinder.

Someone else said the same thing about it running on one cylinder, it would still have a noticeable acceleration. This motor just doesn't seem to at all. i will check for spark though

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

As funny as my story may sound, it is true!!!!!!!!!!!!!!!

When I first got my boat and twin 1961 johnsons last summer I went over each motor and replaced and cleaned everything that was dirty or cracked as in coils ect.

I put each outboard in a 45 gallon drum of water. Fired each unit up to test. They both would idle all day but would not rev past half throttle.

I concluded because they smoked so much they were trying to burn their own exhaust and thus would be runing too rich.

I used a fan to blow the fumes away from the barrel and all way well.

Put them both on the boat and headed for the rideau river where they run perfectly.

Hope you issue can be this simple

cheers

Problem here is the one having problems is running on the lake

 

[1946Zephyr]

Re: 1958 18hp Johnson hesitating and lacking power

Yep, I agree. It sounds like it has one cylinder dropping in and out. Did you replace the spark plug wires too? I would also check the connections on both ends of the spark plug leads. Under the spark plug boot, the spring connector tends to rust out and lose contact with the high tension lead. I usually trim off where the tong went through the wire and re-attach it with a fresh connection.

Make sure your points are both still at .020 gap.

Compression on a good cylinder should be around 100 psi or better and the compression on both cylinders should be very close to the same, or it'll run rough.

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

Yep, I agree. It sounds like it has one cylinder dropping in and out. Did you replace the spark plug wires too? I would also check the connections on both ends of the spark plug leads. Under the spark plug boot, the spring connector tends to rust out and lose contact with the high tension lead. I usually trim off where the tong went through the wire and re-attach it with a fresh connection.

Make sure your points are both still at .020 gap.

Compression on a good cylinder should be around 100 psi or better and the compression on both cylinders should be very close to the same, or it'll run rough.

yeah it has new spark plug wire, and new boots. I actually found a 30 foot roll of hypalon copper core spark plug wire in the shed. It must have been 20 years old

 

[tashasdaddy]

Re: 1958 18hp Johnson hesitating and lacking power

so you built you own wire, i like to strip the wire back an wrap some wire around the plug connector spring, ensures good contact. also the high speed carb adjustment, with the motor off, in gear, watch the timing plate, is it advancing all the way around? could be hanging up, and not turning to full throttle. the have a rod, that blocks the timing plate so the motor cannot be over reved in neutral, it could be stopping the timing plate.

 

[1946Zephyr]

Re: 1958 18hp Johnson hesitating and lacking power

yeah it has new spark plug wire, and new boots. I actually found a 30 foot roll of hypalon copper core spark plug wire in the shed. It must have been 20 years old

Well, if the lead still looks clean and the rubber is plyable, then being 20 years old isn't bad. Just as long as it is the right kind of lead for the motor.

The faces of the coils have to be perfectly even with the machined surfaces on the armeture plate, or that could cause a fault. If they're off any, then the coils could drag on the flywheel, therefore creating a spark issue.

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

The faces of the coils have to be perfectly even with the machined surfaces on the armeture plate, or that could cause a fault. If they're off any, then the coils could drag on the flywheel, therefore creating a spark issue.

okay yeah, this may be a cause. Because the coils were rubbing, i mounted them back past the even point. They aren't perfectly even, but i did this with the 15 hp and it has no problems. This may be causing a weak spark

 

[1946Zephyr]

Re: 1958 18hp Johnson hesitating and lacking power

I usually use a blade from a utility knife to line things up. The better they're lined up, the better your spark will be.

 

[tashasdaddy]

Re: 1958 18hp Johnson hesitating and lacking power

agree get them flush, or they will not perform properly.

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

update: I notice the throttle timing is off. The timing mark is well past the throttle cam when it begins to open up. I can only think of adjusting the cam plate on the armature to fix this. I have even compression, both coils are hot, the motor runs with either spark plug wire disengaged. Also in reverse, i get full power (full reverse power) but it kinda revs up, i keep it 100%, then it kicks up more rpm's with no warning.

 

[bktheking]

Re: 1958 18hp Johnson hesitating and lacking power

Point gap set properly?

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

yeah, imma get some new spark plugs, J6C, all ignition is set, except for the coil mount and timing apparently

 

[KB1]

Re: 1958 18hp Johnson hesitating and lacking power

Has anyone else noticed in the vid that the high speed jet's knob is dancing around? Is the knob just loose or is the entire jet loose? That's one concern for sure!!

 

[restornator]

Re: 1958 18hp Johnson hesitating and lacking power

Has anyone else noticed in the vid that the high speed jet's knob is dancing around? Is the knob just loose or is the entire jet loose? That's one concern for sure!!

i packed it (needle) more tight, and it does not dance anymore

 

[moonfish]

Re: 1958 18hp Johnson hesitating and lacking power

It's all true. They'll suck air around either needle if that packing isn't pretty tight. It's easy to run a wire so it interferes with the armature movement also. It's easy to put something together wrong and get some head scratcher. I won't tell you how I know...

 

[Sargent Skiff]

Re: 1958 18hp Johnson hesitating and lacking power

update: I notice the throttle timing is off. The timing mark is well past the throttle cam when it begins to open up. I can only think of adjusting the cam plate on the armature to fix this.

This adjustment is important. Loosen the cam plate and move it out until the roller (the roller is still there, isn't it?) aligns with the index mark on the flywheel at the point at which all of the slack is taken up in the linkage and the throttle butteryfly just starts to open. An old trick is to put an alligator clip with a length of wire on the butterfly shaft to exaggerate the motion, which makes it easier to tell the exact instant the butterfly starts to move.