comment from an intelligent shource
A 1987 Evinrude E50TLCUD bogging down is almost always caused by fuel, air, ignition, or exhaust issues. On that era of 2-stroke outboard, a few causes are especially common:
Most likely causes
1. Fuel delivery problems (very common)
- Dirty or clogged carburetor jets → engine starves under throttle
- Old fuel / water in fuel → poor combustion
- Weak fuel pump diaphragm → can’t keep up at higher RPM
- Clogged fuel filter or line → restricted flow
Classic symptom: runs OK at idle but bogs when you accelerate.
2. Carburetor out of adjustment
- Low-speed or high-speed mixture screws not set correctly
- Float level off inside carb
Causes hesitation or “choking” feel when throttling up.
3. Ignition issues
- Weak spark from:
- Bad ignition coil
- Faulty power pack
- Worn spark plugs
- Timing slightly off
Feels like misfiring or uneven power, especially under load.
4. Air leak / intake issue
- Cracked intake gasket or loose carb mount
- Vacuum leak → lean mixture
Engine may surge or bog unpredictably.
5. Choke sticking partially ON
- Manual or electric choke not opening fully
Engine runs overly rich → bogs, smokes more.
6. Exhaust restriction
- Carbon buildup in exhaust housing (common in older 2-strokes)
Engine struggles to breathe at higher RPM.
7. Cooling-related limp behavior
- Overheating (bad impeller) can cause power loss
Check for weak water stream (“pee stream”).
8. Prop or load issue
- Damaged prop
- Too much load (over-propped or heavy boat)
Engine bogs when trying to reach RPM.
Quick checks you can do
- Pump primer bulb while running → if it improves, fuel pump issue
- Try fresh fuel mix (correct oil ratio)
- Inspect spark plugs (wet, black, or fouled?)
- Check fuel lines for softness/cracks
- Look for strong spark on both cylinders
Most common on this exact motor
For that model/year,
90% of bogging complaints end up being:
- Dirty carb(s)
- Weak fuel pump
- Old fuel system hoses
If you want, tell me:
- Does it bog only when accelerating or also at full speed?
- Does pumping the bulb help?
- Is there smoke or sputtering?
I can narrow it down to 1–2 likely causes pretty precisely.
when accelerating
If your Evinrude E50TLCUD
bogs specifically when you accelerate, that narrows it down a lot — this is almost always a
fuel delivery or carburetor transition problem on these 2-stroke engines.
Here are the
most likely causes (in order):
1. Dirty / partially clogged carburetor (TOP cause)
- The high-speed jet or transition circuit is restricted
- At idle → OK
- When you throttle → not enough fuel → bog
Very common if:
- Fuel sat over winter
- Ethanol fuel was used
Fix:
- Remove and clean carb thoroughly (not just spray — full disassembly best)
2. Weak fuel pump
- Pump can supply idle fuel but not enough when demand increases
Test:
- While accelerating, squeeze the primer bulb
- If engine picks up → fuel pump is weak
3. Air leak in fuel system
- Cracked fuel line, loose connector, bad tank fitting
- Engine sucks air → leans out when accelerating
Symptoms:
4. Carb adjustment off
- Lean mixture on acceleration
Especially if someone adjusted screws recently
5. Choke not opening fully
- Engine runs too rich when throttle applied
Usually comes with:
- Extra smoke
- “Blubbering” sound instead of clean bog
6. Ignition weakness (less common but possible)
- Coil or power pack weak under load
Usually:
- Feels like misfire, not just bog
Quick diagnostic trick (very useful)
Next time it bogs:
- Pump the primer bulb
Improves → fuel pump / fuel restriction
No change → carb or ignition
Simple checklist
- Fresh fuel mix?
- Fuel lines soft or cracked?
- Spark plugs fouled?
- Carb ever cleaned recently?
Bottom line
For your exact symptom (
bog on acceleration only), the odds are:
~70% carb dirty
~20% fuel pump / fuel line issue
~10% everything else
) and walk away .