Originally Posted by mick
Another thing to consider is where you get fuel from nowt like cheap supermarket fuel for fecking injectors up
I totally agree and other some things to consider when having problems with idle and acceleration. Based on my experience over the years using ribs/outboards on several continents is that most outboard engine issues is because of the fuel and the fuel delivery system being effected by bad gas, lack of proper care of fuel and proper storage of fuel.
Be careful of gasoline with E10 (10%) Ethanol. E5 or lower is preferred.
Ethanol is produced from corn, soybeans, sugar cane, or other organic material. It is blended with gasoline (10% ethanol, 90% gasoline) to produce E10
Most newer engines are designed to use E10 but it's the older fuel delivery systems, hoses and fuel tanks that are the problem.
Ethanol is an excellent solvent, drying agent and cleanser. It will clean or dissolve some parts of, and deposits in, fuel storage and fuel delivery systems, including some fuel tank materials. The dissolved material can clog filters or pass through and leave deposits on fuel injectors, fuel pumps, fuel pressure regulators, carburetor jets, intake tracts, valves, and valve guides.
*This was my problem with my Honda outboard. The rib with this outboard was older and the fuel sat in the tank for a while being stored prior to my buying it.
In storage, gasoline immediately starts to oxidize and deteriorate. The older it gets the more it deteriorates and the more likely it will cause hard starting, performance issues and gum deposits that clog the fuel system.
If the gasoline in your fuel tank and carburetor has significantly deteriorated during storage, you may need to have the carburetor and other fuel system components serviced or replaced.
For me, my jets had gum deposits and varnishing that really effected motor idle.
Also: Ethanol is hygroscopic, which means it attracts and retains water. The lower the fuel level in the tank, the more likely you will experience water contamination. If the contamination is severe, a layer of alcohol/water can form at the bottom of the fuel tank. This is called phase separation, and can cause damage to the fuel tank and engine.
Keep your fuel tank as full as possible with fresh fuel and out of direct sunlight.
Install additional water separating fuel filters in your boat and keep spare filters on-hand.
Use a fuel stabilizer along with fresh fuel when your boat is stored (follow the procedure noted in your owner’s manual to ensure proper storage).
Use a gas station with a reputation for quality fuel and with high volume.
The length of time that gasoline can be left in your fuel tank and carburetor without causing functional problems will vary depending on a variety of factors.
Fuel formulations vary by region. Depending on the region where you operate your outboard, fuel may deteriorate and oxidize more rapidly (in as little as 15 days).
Other factors include:
The air volume in a partially filled fuel tank promotes fuel deterioration.
Very warm storage, high humidity and variable temperatures accelerate fuel deterioration.
Fuel deterioration problems may occur in less than 30 days if the gasoline was not fresh when you filled the fuel tank. Purchasing fuel from a busy, reputable gas station is recommended.
Last thing. People talk about using high octane for better performance in there outboard. Outboards are relatively low compression motors and prefer longer burn gasoline and don't need high octane. Idle can be effected and not run as smooth with high octane short burn fuel.
Premium high octane fuel is used for higher compression engines, it actually burns slower, which helps reduce detonation but you Lower horsepower motor may idle better with lower octane (longer burn). Check your manual for recommended octane. It may surprise you.
Hope this info helps