An EFI (electronic fuel injection) outboard meters fuel with a computer and injectors; a carbureted outboard mixes fuel and air mechanically. EFI motors usually start more easily, especially when cold, run more smoothly, use somewhat less fuel and are far less prone to the gummed-up carburetors that ethanol fuel causes in motors left sitting. Carbureted motors are simpler, cost less and can be repaired without a diagnostic tool. In small sizes, both are still sold.
EFI vs carbureted at a glance
| Carbureted | EFI | |
|---|---|---|
| Starting | Often needs choke; harder when cold | Easier, usually no choke |
| Running | Good when the carburetor is clean | Smooth, adjusts to temperature and altitude |
| Fuel use | Slightly higher | Slightly lower |
| Sensitivity to stale fuel | High: varnish clogs jets | Lower, though injectors and filters still need clean fuel |
| Repairs | Simple, mechanical | Needs electrical checks and sometimes a diagnostic tool |
| Price | Lower | Higher |
Is EFI better than a carburetor?
For most owners, yes: easier starting and less trouble from stored fuel make EFI worth the extra cost, especially if the boat sits for weeks between uses. A carbureted motor still makes sense for a light portable you use often, want to keep simple, or may need to fix far from a dealer.
Stored fuel is the big difference
Most carbureted outboard problems after storage come from fuel varnish in the small idle jets; see outboard won’t idle and ethanol in boat fuel. EFI systems are sealed and pressurized, so they suffer less, but they still need fresh fuel and clean filters; see outboard fuel filter.
EFI outboards in our range
In our catalog, the listings that name EFI are Mercury models from 9.9 to 20 HP, starting at $2,865.00 for a 9.9 HP. Other brands’ listings state their fuel system in the specifications; check each one.
Maintenance differences
Carbureted motors benefit from running the carburetor dry or draining the float bowl before storage. EFI motors need a fuel stabilizer and fresh fuel, and their high-pressure filters should be changed on schedule. Both need the usual oil, gear oil and impeller service; see outboard motor maintenance.
Battery needs
Some small EFI motors can start and run without a battery once pulled over; others need battery power. Check the listing and manual, especially for tiller pull-start models; see electric vs pull start.
Related: outboard primer bulb, how to winterize an outboard and Tohatsu vs Mercury.
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