Electronic fuel injection


The “i” suffix in the California 1100i model name signifies “injection” as opposed to carburetor delivery of fuel. Moto Guzzi introduced electronic fuel injection (EFI) in the early 1990s largely motivated by emission control regulations. Since EFI deploys various sensors — air/oil temperature, throttle/crankshaft position, and barometric pressure — to regulate the fuel-to-air mixture, this technology minimizes unburned hydrocarbons, a major component of smog.

Increasingly, EFI is favored for other reasons: more torque, better gas mileage, enhanced cold weather and high altitude operation. For big twin engines like the 1100, EFI also delivers about 50% more throat diameter (read more power) than corresponding carbs can. For this reason, the non-EFI California 1100 was phased out of production in 1997.

EFI combines two basic systems: electronics to time the spark at the optimal point for combustion, and air/fuel delivery for just the right optimal power mix.

Electronic control

See also the harness discussion.

Apart for adjusting wire lengths to fit the cyclecar chassis, the electronic components will be reused without modification, with the exception of two relays (component 3 in drawing above) that will be refreshed with new units .

Air/fuel mixing

While the basic plumbing will remain the same, the configuration of the engine in the cyclecar chassis as well as a completely different fuel tank will necessitate repositioning of the fuel filter, pump, and regulator behind the twin cylinders.

The large airbox filter housing will be replaced with standalone twin cylindrical air filters. Fuel pump and filter will be refreshed with new parts, but their function will remain the same.

The Guzzi diagram above shows vacuum tubes (in yellow) running from the fuel pressure regulator (3) back to the intake manifolds by the throttle body. This is apparently obsolete. A pressure regulator typically does equalize based on manifold vacuum, but given the twin cylinder 1100 orientation, this may have created a pulsing vacuum that, in turn, caused premature regulator membrane failure. Guzzi calls this component a “pressure relief valve” so simply venting it to the atmosphere appears to work fine.

The purpose of the pressure regulator is to step down the fuel pump’s 44 PSI to the EFI operating pressure of 36.8 ± 3 PSI (an average reduction of 7.2 PSI). A modern adjustable regulator with a gauge might be substituted pending further research.