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1975 Johnson 4hp engine

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noblo88

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So I have a 1975 Johnson 4 horse and it wont start. It has new spark plugs with good spark, New fuel pump that works well, cleaned out the carb like 5 times. its reading a 90 for compression. I've narrowed it down to this, the heads are not getting fuel in them therefore it wont start because no fuel but i don't know how to fix that. what could possibly be blocking the passage way to the heads for the fuel to not get there? I tried spraying some startin fluid in er but nothing happened either? Any tricks or ideas, please help.
 
What happens if you pull spark plugs and pour a little mixed fuel directly into both cylinders and try starting it again ?
 
Compression or 90 psi is okay. Spark being "good" means nothing. With the spark plugs removed, the spark should jump a 1/4" gap with a strong blue lightning like flame... a real SNAP! Does it?

(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 1/4" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4
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(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP embossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
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If you have proper compression and ignition (spark), the problem is usually a clogged carburetor... very easy to overlook something in that area.
 
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its got a big ol spark nice and blue and makes a good snap, the carb was cleaned very throughly, is there any chance there is something in the block?
 
If fuel is not getting to cylinders via carb. internal blockage in carb. still exists. Can you verify fuel bowl is getting proper mixture 50/1. Is float height set at right spec. What happens when squeezing primer ball before start up. Is carb secured on manifold snugly,vacuum leak at gasket?
 
I would try the fuel in the cylinders trick again and take it easy. If you pull 3 or 4 times with the choke out and it doesn't fire or sound like it's even trying, push the choke in and try again 3 or 4 times. Even if you put too much fuel in there, wait 30 mins and try this one more time.
If you're getting nothing like it's even trying to fire, that likely rules out if it's fuel or not and I'd move back to insuring its ignition.

I've done this on a few based on the folks recommending it on this forum and it fires up and dies within 4 or 5 seconds.
This tells you that spark is fine and that there likely is a fuel blockage (likely in carb, sorry). If it doesn't fire, it's most likely ignition and do what the guys say above. Double check your spark and timing.
 
IS your fuel mixture correct as in post#9. Are you using old fuel,old tank? Starting fluid doesn't provide adequate lubrication use fuel mixture instead.
 
i dont really think you can set the fuel bowl, the only screws she has are the slow and high speed screws. and when i prim it, it goes and goes for a squeeze or two and i see the fuel goin into the carb and then it stops and i cant squeeze anymore.
 
FishyBC if i do what you say and nothing happens, so i check the timing and spark and its good, put some fuel in (not a lot) should i put some fuel in each cylinder? say she does fire for a few seconds, so then it would be the carb, but if i go buy another carb rebuild kit then do it all corectly and it still doesn't go, is there a chance there is something in the block that would be causing it to not get fuel into the cylinders???
 
You're obviously overlooking something pertaining to the carburetor. Did you adjust it as per post reply #5?

No, there's nothing in your crankcase/block.
 
Ok,you said you cleaned the carb 5 times.Did you disassemble the carb to clean it,paying close attention to the idle circuit and high speed orfice and float level? If not give that a try, but it should pop when you spray mix in the cyls.
 
Does spark jump a gap of 1/4" or more, yes or no ??-----------Have you switched the plug wires to test and see if that makes a difference ?
 
If you tried starting fluid and it did not fire, you are missing something there, staring fluid will start a dead horse
 
noblo, again if you squirt it with starting fluid and it did nothing, not even backfire or some kind of explosion there are only two thing to look at, spark or compression, if you said he compression was 90 psi then the sparks dies under compression because is not good.
 
You said the ignition was perfect,we can not do it for you over the computer.Answer #18 if you want to continue.
 
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joereeves, I wish I was, i need a week or two to get back and let you know how everything turns out, kinda hard to do it when you live in the barracks on a Marine Corps base.
 
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