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Johnson 4HP Rebuild Issue - Dry Spark Plugs

G

Griggs

New member
First post here. First engine rebuild as well. Forgive me if I may have overlooked a thread that touched this topic. I looked and found a few topics that were similar to my problem but I've tried what worked for them and it isn't working for me. Here is my problem:

I recently rebuilt a 1974 Johnson 4 HP (4W74R) from top to bottom. Everything is put back together properly. I installed a new ignition system and it gives a good spark on both cylinders but when I go to start it, it isn't turning over. I tried and tried with no joy. I took the plugs out and they were both bone dry. I sprayed some starting fluid in both cylinders and carb inlet to no avail. I have the slow speed needle set at 1 -1/2 turns from a gentle seat and the high speed setting at 1 full turn. I pump the primer bulb until it is hard and see fuel getting to the Carb. and the bowl is filling up but no fuel is getting inside the engine. I've also set the correct timing with throttle at wide open. This is a dry start so there is no fuel in the motor whatsoever.

What am I doing wrong?? I am probably making a newbie mistake but I have thought of everything and no fuel is getting to the engine for some reason. I even took the carb off the block and no fuel. I am stumped! Any help would be appreciated! Thank you!

Bret
 
What does rebuilt top to bottom mean? Did you have the powerhead apart, pistons out and everything?

Does it have compression? How many psi?

Your last sentence, carb off the block. Are you saying there is no fuel in the carburetor?
 
fdrgator said:
What does rebuilt top to bottom mean? Did you have the powerhead apart, pistons out and everything?

Does it have compression? How many psi?

Your last sentence, carb off the block. Are you saying there is no fuel in the carburetor?
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When I say "top to bottom" I mean I took the entire engine apart, cleaned it, inspected the tolerances, replaced anything that had to be replaced, polished the journals, etc. It was broken down all the way.

I'm testing the compression today, I have to go out and get a new compression tester.

When I say "carb off the block" I meant I took it off the powerhead and inspected it to see if fuel was getting in the engine and found the bowl was filling up but no fuel was getting inside the engine. The carb. has fuel getting to it but the spark plugs are dry.
 
racerone said:
I say you have no spark.-----With fuel in the spark plug holes it should bark like a big dog for a second !
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I do have spark though. I have tested both plugs in a spark plug tester, both have solid sparks (not weak). When I took both the spark plugs out, they were both dry and both had a little soot on them. I cleaned the soot off and tried it again with no luck.
 
Put some fuel in the spark plug holes.----Put plugs in.----Pull it over.----If it does not bark like a wild dog , you have no spark !----Note----I was repairing outboards BEFORE that motor was built.
 
If you have spark but it is not firing it makes me think your coil wires might be switched. In other words you have spark but it is sparking at "bottom dead center" as opposed to the "top dead center" that is required to run an engine. Switch the coil clips to confirm if this is the case. The other alternatives is you have not set the point gap properly, have poor compression and perhaps a few other issues. The coil switch should be an easy one to confirm or eliminate.
 
racerone said:
Put some fuel in the spark plug holes.----Put plugs in.----Pull it over.----If it does not bark like a wild dog , you have no spark !----Note----I was repairing outboards BEFORE that motor was built.
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I will try this instead of the starting fluid. Thank you.
 
optsyeagle said:
If you have spark but it is not firing it makes me think your coil wires might be switched. In other words you have spark but it is sparking at "bottom dead center" as opposed to the "top dead center" that is required to run an engine. Switch the coil clips to confirm if this is the case. The other alternatives is you have not set the point gap properly, have poor compression and perhaps a few other issues. The coil switch should be an easy one to confirm or eliminate.
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When you say coil clips, what are you referring to? Can you explain as if you are talking to a 5 year old? haha. I have a set of feeler gauges and set the gap on the points to .02 at the arrow that is to the right of the 'TOP' on the bushing for each set of points. Please let me know if this is incorrect. This is what I have gone off as I have seen this in an outboard forum. Are you saying possibly switch my coils? Are the coils not universal for this type of ignition? Or are you saying switch the coil leads and place them on the other set of points instead?
 
Hurry----visit----leroysramblings------A wonderful site full of information to learn about this simple magneto ( coils ) and how to work on this motor.
 
Griggs said:
When you say coil clips, what are you referring to? Can you explain as if you are talking to a 5 year old? haha. I have a set of feeler gauges and set the gap on the points to .02 at the arrow that is to the right of the 'TOP' on the bushing for each set of points. Please let me know if this is incorrect. This is what I have gone off as I have seen this in an outboard forum. Are you saying possibly switch my coils? Are the coils not universal for this type of ignition? Or are you saying switch the coil leads and place them on the other set of points instead?
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I am not precisely familiar with the 4 Hp motor of that vintage but I am familiar with the 9.9Hp of the same year. Those motors, if I recall, have wire clips coming down from the flywheel that clip to individual coil clips. One for the top cylinder and one for the bottom cylinder. If those clips are reversed (top wire going to bottom cylinder and vise versa), you will still get good spark, but it will be timed at precisely the worst time. In other words instead of the spark firing when the cylinder has just compressed the fuel with the piston sitting at top dead center of the cylinder, it will spark when the cylinder is at the bottom of the cylinder and of course, the motor will never run that way.

I assume the 4 Hp has the same kind of coil clips but I can't say for sure. Your point gap sounds like it is set OK.
 
Yes I would agree check to make sure you're getting spark at the proper end of the Piston cycle. The other thing to check is if you can get a chunk of Hose up to the carburetor opening and blow in can you blow air in and it should sound kind of like a saxophone reed fluttering? I don't remember if it's possible but did the reed plate get put in backwards? The reeds should be on the crankcase side of the plate, not the carb side.The other thing did you get the right gasket on the right side of the reed plate if it is put in properly? I see that the complete assembly is still available for $23. If your reads are wore out or not ceiling off like they should that could cause an issue. Especially if you're getting fuel to the carburetor but nothing through the engine. The other thing is yes try putting some gas in the cylinder it should fire up. Although that's not a guarantee as I found out with my 1932 Johnson putting gas in the cylinders will not make it fire up it needs to be extremely rich in the carburetor to get it started and then you lean it out. But that shouldn't be the case with this motor as it should start up normally.
 
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The other thing is when you put this back together did you get the Pistons orientated the correct way? That is to say the sharp side of the Dome should be facing the intake ports and the shallow side facing the exhaust? The only reason I say this is that I got a three horsepower Evinrude from my dad for repair and the guy that had the motor apart previously put the Pistons in the wrong way so he could get it started but he could not build any speed because the engine would not breathe properly. I took it apart and put everything back together the correct way and it's a good solid motor now.
 
The OMC people back then were not a bunch of dummies.----Take a good look at the positioning of bolt holes on these motors.----Impossible to install reed plate the wrong way !
 
racerone said:
The OMC people back then were not a bunch of dummies.----Take a good look at the positioning of bolt holes on these motors.----Impossible to install reed plate the wrong way !
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Never said they were. Thats why I stated "don't know if I was possible". Just trying to weed out the simple things. If you have correct spark, air and direct fuel in the plug allows it to start. The next thing I would double check is the carb rebuild. All parts in the correct way? Float height correct?
I just had a 9.9 come to me that would not idle. The previous mechanic missed a broken brain box wire and forgot to install the plastic cup seal down in the carb for the idle needle. Fixed those two and smooth as silk. The other guy dumped 600 bucks into it and gave it back saying "thats the best it will do".
 
might you have put carb float in upside down? Blow some air into the carb (via fuel intake orifice) with a finger on the underside of the bowl. When bowl is low, it should allow air through, when bowl is horizontal it should prevent you from blowing air through.
 
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