Originally Posted by ali_seton
please could you help..... i have a 1990 or a 1998(im not sure) 40hp Mariner electric start and trim engine. The fuel usage is completely apauling like £28 in 5hrs of going 4 knots!!! THIS CANT BE RIGHT!!! Please can someone advise on what they think about sorting it out so its more economic!!
If it's a very used engine, make a compression test if OK, are you using the correct gapped spark plug type ? If worned or too fouled, change for new ones, if OK, would think in changing complete carb accesories for new ones, with time and use high speed orifice and jets tend to wider their gas hole passages comsumming more gasoline as before. Check also for any gas leaks in gas filter, pump, hoses, etc. Don't know if your engine is a Tohatsu or Yamaha manufacture rebadged to Mariner brand, Tohatsu manufacture uses rack & piñon throttle arm photo 1, Yamaha uses cable drive throttle arm photo 2.
If it were a Tohatsu the factory consumtion parameters are:
Full Throttle Engine RPM Range : 5200-5800 rpm
Full Throttle Engine Comsumtion (WOT) 4.49 Gal/Hour (17 Ltr/Hour) 3.78 Ltr to Gallon
Does not state if tested on a factory test tank, or on a boat with calm waters.