If your outboard runs fine at idle but won't reach full RPM under load, you're losing power somewhere. Here's how to find it.
What to Check
1
Fuel restriction
Clogged fuel filter, kinked fuel line, or anti-siphon valve failure starves the engine under load.
2
Old / bad fuel
Ethanol-blend fuel sitting more than 90 days causes power loss. Drain and refill with fresh.
3
Lower unit / prop
Damaged prop, slipping hub, or seized lower unit will limit speed even with full RPM.
4
Spark plugs
Fouled plugs cause misfire under load. $30 fix.
5
Compression
Low compression on a cylinder = top-end work needed.
When to Call Us
If fuel and plugs check out, get a compression test — we can do it slip-side in 30 minutes.