Motor Still Won't Fire After New Ignition Components and Carb Rebuild

[adt2]

Howdy, folks. Another update on my ongoing 1957 Johnson 35HP tune-up. I have good news and I have bad news. The good news is, the motor turns over just like it did before I tore it all down and rebuilt the carb and installed new ignition components.

The bad news is, the motor still will not fire. It started for a moment, but before I could get the throttle moved to rev it up, it died and hasn't fired since. Starter motor just spins the flywheel endlessly with no indication of combustion. I have the slow-speed needle at 1-1/2 turns out from lightly seated and have tried with and without choking. Fuel is fresh and bulb is firm. Plugs and wires are all new, as are coils, condensers, and points (with correct 0.020" gap).

Now what?

 

[milliesdad]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Check compression, spark and fuel.

If you have all three, God said it has to run.

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Compression is ~120psi on each cylinder (or it was before I rebuilt the carb and put in new ignition stuff; would any of those repairs change it?). Fuel is fresh and flowing; I know because I forgot to tighten the hose clamp where the fuel line connects to the carb and sprayed fuel everywhere when I pumped the bulb.

Re: testing the spark...I hate to admit this, but I don't really know how to do that. The plugs are new. The wires are new. I bought a spark tester but I can't figure out how to use it.



Had I seen the reviews of this thing on Amazon before I bought it at the local auto parts store, I wouldn't have bought it. At least it didn't cost much.

 

[Rick.]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

It's pretty simple to use. Open the gap to 1/4 inch, put your plug wire on one end and clamp the other to a good ground on the block. The other wire should be gronded at the same time and then crank your engine and look for a blue/white snappy spark at the 1/4 inch gap. Then do the other plug. Have you checked to see if your plugs are wet with fuel after cranking. They should be. Best of luck. Rick.

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

When you say the other wire should be grounded - do you mean the other plug wire? It shouldn't be on the other plug? How do I ground it?

 

[AlTn]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

both spark plugs are removed for the spark test....I use a jumper wire made from ~ 16" length of insulated wire with 2 thin long aligator clips < 1 on each end >...one clip goes up into the sparkplug boot and clamps into the wire coil that slips over the spark plug when it's installed, the other end just clips to a good ground on the powerhead...you may have to use a darkened area to see the spark well...btw the clamp on the spark tester has to be on a good ground to work properly...as another member has posted before you can always use an old sparkplug and open the gap to ~ 1/4",hold the threaded portion of the plug to the block and check for spark

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Okay, I'll go out and re-test. I just used the tester on one plug wire at a time without removing the other plug, and I got blue spark across a 1/4" gap on each wire.

 

[AlTn]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

well, you've established you've got spark....the reason for both plugs out is one of safety , your motor is capable of starting on 1 cylinder..it's also easier on the electric starter w/o any compression to overcome...get some fuel mix into each sparkplug hole, reinstall the plugs and see if you can get it to fire....you can move onto the fuel delivery systems if it fires

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

No dice. I squirted a bit of fuel mix into the plug holes, reinstalled the plugs, and...nothing. Starter spins the flywheel, but no firing. How much fuel should I be putting in the holes? I used a plastic glue syringe, sucked up about a tablespoon of fuel mix and split it roughly evenly between the two plug holes.

 

[lindy46]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

How are your spark plugs? I just went through a no-spark issue on a 1976 35hp Evinrude, and I put new Champion plugs in it. No spark. I put the old NGK plugs back in and had fine spark. I went and got another set of new plugs and they wouldn't fire either. I tested both sets of new plugs and they had no continuity. Both sets were Champions, made in Mexico. Never had that happen with Champions before. So the simplest things can sometimes be the problem.

 

[milliesdad]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Did you use a torque wrench to tighten the flywheel nut?

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Spark plugs are new, but I don't know how to tell if they're sparking...? Re: torquing the flywheel nut, yes I did but I have no idea if I got it tight enough. The torque wrench I borrowed was for inch-lbs, not ft-lbs; I set it to 45 in-lbs and I couldn't make it "click off." So the nut is as tight as I could get it.

 

[boobie]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Maybe a sheared flywheel key.

 

[Daviet]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

45 in-lbs is only about 3 1/2 ft lbs. As boobie suggested, check the flywheel key to make sure you didn't shear it and tighten it to the correct ft lbs.

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

I might not have been clear; I think there was something wrong with the torque wrench I borrowed. I'm a pretty big guy, and I tightened this thing as hard as I could. I could use a couple of fingers and get the nut to 3-1/2 ft-lbs. I had a foot braced to the transom pulling against the wrench - pretty sure I'm at least 45 ft-lbs.

But if I grant for a moment that the flywheel key is sheared - does that impact the motor not firing? The flywheel turns just like it always did when I hit the starter. The motor still never even fires.

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

By the way - I did check the plugs for continuity, and both of them are fine.

 

[Daviet]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

If the flywheel key is sheared the engine will still spark, but the spark will not be delivered at the proper time and the engine will not start.

 

[adt2]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

I'll double check tomorrow but I don't think that's the problem. The motor is exhibiting exactly the same behavior it did before I did any of the repair work, and the flywheel key was not sheared when I pulled it.

 

[Daviet]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

It takes three things to make your engine run, timed spark, compression and fuel.
If your flywheel key is not sheared, and the points are set correctly, and your spark will jump a 1/4" air gap and is bright blue you are Ok.
Make sure you have the correct plugs, gapped correctly.
That only leaves fuel. Have you tried to squirt some fuel mixture into the carb and see if it will fire?

 

[lindy46]

Re: Motor Still Won't Fire After New Ignition Components and Carb Rebuild

Flywheel nut MUST be torqued to 60-65ft.lbs. on that motor. Any less could result in a sheared key.