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Johnson 1998 50hp Starting Issue

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boat_guy

New member
I have Johnson 1998 50hp J50PLEEA with VRO pump. When bought it seller told me about damaged lower unit.

I put engine on the stand and connected fuel, VRO tank, battery, BRP Side remote control.
Removed lower unit and attempted to start engine to confirm working condition.
First time I tried, engine would start and run for few seconds and then stop. Subsequent attempts to start were unsuccessful.

1. Checked fuse. Good.
2. Verified battery. Charged to full. Tried to start - spins but no start.
3. Removed spark plugs and measured 0.035 for both and put back. Tried to start - spins but no start.
4. Removed each spark plug, connected rubber boot wire, touched the metal with spark plug. Tried to start - visually confirmed spark on each.
5. Removed starter, disassembled. Removed metal powder from magnets, cleaned rust a bit, added grease and assembled. Tried to start - spins but no start.
6. Removed VRO pump, disassembled. Visually inspected, no rips/holes/cracks on both membranes or gunk on inside. Re-assembled and re-installed back.
7. Disconnected hose into carburetor from prime solenoid. Tried to start - visually confirmed fuel spaying on each hose.
8. Remove carburetors, disassembled. Removed all gunk and cleaned all. Installed back. Manually pump fuel - hear fuel filling up each carburetor (removed screw to confirm). Tried to start - spins but no start.
9. Removed spark plugs and engine cover (with spark plug holes). Verified no chips, scrapes or rust on the insides of both cylinders. Tried to start - visually confirmed fuel mist spraying from each cylinder. Put engine cover back and re-connected spark plugs. Tried to start - spins but no start.
10. Checked stator with multimeter. Black/yellow - ground. Orange to Orange/Black - 400ohms. Brown to Brown/Yellow - 800ohms.
11. Checked timer with multimeter. White to Green - 27ohms. White to Blue - 27ohms.

After few attempts to start engine would backfire with loud bang and fuel would drip from opening below where lower unit installed.

What can I do next? Thank you for your help.
 
12. Removed flywheel. Check for no physical damage to stator, timer and key. Re-assembled. Tried to start - spins but no start.
 
Did you check ohms on the starter armature ?-----Are you pushing the key in and holding it in while cranking it over ?-----Does spark jump a gap of 3/8" on a test device , yes or no ?----What is wrong with the lower unit ?-----Or have you rebuilt it ?
 
I checked started for resistance and shorts before assembling.
Start key held by kill switch clip so I am not pushing in, just turning.
Ordered adjustable ignition spark test tool. Will post reading later.
Rebuilding lower unit. Ordered parts and such.
 
Got adjustable ignition spark test tool in mail today today. Set to 7/16in (10mm).
Connected to first(top) cylinder. Tried to start - visually confirmed stable spark in tool.
Connected to second(bottom) cylinder. Tried to start - visually confirmed stable spark in tool.

Any other ideas? Please, any help would be much appreciated. Thank you.

P.S. Got timing light as well. Will check sync with timing light test tomorrow.
 
It's possible the power pack could have internal problems and not firing at the right time.Take your plugs out and rotate the motor to top dead center on #1 cylinder and mark your flywheel the do the same with #2.Hook up your timing light to #1 and crank over the engine,you should see the #1 mark flash and only #1,do the same on the #2 cylinder.If you see any other number flash when you do this you have power pack problems.
 
Ran timing light test today. 1st cylinder spot light pointed far away numbers on flywheel. I removed flywheel, key is fine. One of two things(or both) could be faulty - timer base or power pack. Timer base looks a bit scuffs on the inside.

Timer base $200, power pack $100. How would I know what to replace?

flywheel inside.jpg

flywheel key.jpg

timer base inside 1.jpg

timer base inside 2.jpg

timer base inside 3.jpg

timer base inside 4.jpg

timer base.jpg
 
I decided to attach magnetic ring to the inside on flywheel instead of replacing.
Soaked magnetic ring in gasoline overnight (to soften old glue). Removed old glue, used 200 sandpaper to clean up bumps and uneven surface.
Lined-up notch on magnetic ring with white mark on flywheel.
epoxy.JPG
Used "J-B Weld" epoxy to attach the ring and left it cure for 24 hours.
Assembled all together, added fuel, put into barrel, started and ran for 5 minutes on idle. Everything sounds good.

Thank You for you contribution.
 
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