Logo
FULL SITE MENU

1993 Johnson 115 VJ115TLETS locking up. HELP

N

ngraham

New member
I have a 93 Johnson 115 cross flow. Recently the only way it would run is if I bumped the “choke”. I pulled the carbs and cleaned them, replaced the gaskets and needle and seat. Did a link and sync, joe reeves method WOT timing and now if I run 4000 + rpm’s for a short time, the engine locks up. No high temp alarm but engine is hot and will not rotate until it
cools. Wait 1 minute and it fires back up. It will run slow speed all day. Any suggestions??? I’m wondering about float height? If the float drop was adjusted too low, could that cause this? Did not do this until after carb work.
 
The engine is experiencing thermal seizure (a cold/lean freeze) at high RPMs because it is running dangerously lean. Since this issue started immediately after the carburetor overhaul, a severe fuel-starvation condition is starving the cylinders of fuel and oil, causing extreme friction, overheating the pistons, and soft-seizing the engine.

Do not run the engine above idle until this is resolved, as repeated thermal seizures will score the cylinder walls and destroy the powerhead.
 
  • The Fix: Remove the outer drain plugs on the carburetor bowls and inspect the main jets. Ensure they are completely clear and screwed in tight.
    • The Fix: Remove the float bowls, flip the carbs upside down, and verify that the floats sit level/parallel with the bowl gasket surface. Check float drop to ensure the float hangs down sufficiently to pull the needle off the seat fully without binding.
 
  • The Fix: Re-torque the carburetor mounting bolts evenly. Check that the new bowl gaskets are seated properly and not pinched.
    • The Fix: Re-verify that you subtracted the standard 4-degree offset correctly during static testing (e.g., if target WOT timing is 20° BTDC, static cranking test should set at 16° BTDC).
    • Ensure the VRO or mechanical fuel pump is maintaining adequate pressure at high RPMs and isn't pulling air through a degraded fuel line connection.
 
Elite Boat Engine said:
The engine is experiencing thermal seizure (a cold/lean freeze) at high RPMs because it is running dangerously lean. Since this issue started immediately after the carburetor overhaul, a severe fuel-starvation condition is starving the cylinders of fuel and oil, causing extreme friction, overheating the pistons, and soft-seizing the engine.

Do not run the engine above idle until this is resolved, as repeated thermal seizures will score the cylinder walls and destroy the powerhead.
Click to expand...
Excellent advice. If the OP's engine is locking up solid with a lean seize I would be very concerned there is already cylinder wall damage.
 
What kind of fuel pressure should I be looking for? Idle vs. wide open? Max pressure drop? I did have to sand down both of the carb bowls due to warpage. My float drop may have been set to too much drop. Motor still starts and idles around good.
 
Back
Top