Abstract: A de-aerated aqueous solution having a short foam decay period is employed as a test fluid in a fuel system flow process. To minimize corrosion after testing, the solution is removed from the fuel system by applying subatmospheric pressure to the fuel system and by flowing air through the fuel system.

Abstract: During engine operation at low induction passage pressure, a carburetor main metering rod and idle bleed valve are reciprocated between a rich position and a lean position in response to energization of a solenoid according to a pulse width modulated duty cycle, while during operation at high induction passage pressure, the metering rod and bleed valve are moved to the rich position by a piston/spring combination.

Abstract: In a two-barrel carburetor, a pair of plain tube mixture conduits each has a main well receiving fuel through a flow restriction which opens upwardly from the high point of a metered fuel plenum. The plenum receives fuel through a main jet controlled by a metering rod which is positioned by a vacuum responsive piston, through an auxiliary jet controlled by a metering rod which is positioned by an ambient pressure responsive bellows, and if desired through another auxiliary jet controlled by a manually adjustable metering rod.

Abstract: A carburetor main metering rod is operated by a bracket carried on a vacuum motor or a solenoid armature to control fuel flow through a main fuel passage, and a bleed valve floats on and is operated by the bracket to control air flow to and thus fuel flow through an idle fuel passage. A gage measures the relative position of the bleed valve within an air bleed body to permit proper calibration of the carburetor.

Abstract: A regulating unit senses the pressures in two zones of a recirculation passage to create a control pressure, and a transducer regulates an operating pressure which positions a control valve to provide exhaust gas recirculation at rates which establish the pressures in the zones necessary to maintain the control pressure equal to a reference pressure. Exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is a proportion of induction air flow with the proportion being ruled by the regulating unit.

Abstract: In an internal combustion engine, an exhaust gas recirculation control assembly and an ignition timing control assembly are operated by an induction passage pressure signal transmitted through a control unit. The control unit interrupts the induction passage pressure signal to cut off exhaust gas recirculation and advance ignition timing following operation at an induction passage pressure signal below a particular level for a selected period of time, such as will occur when the engine powers a vehicle during highway driving.

Abstract: In a carburetor, an electromagnet energized according to a pulse width modulated duty cycle has a stationary pole member which drives a pair of permanently magnetic valves against the bias of a pair of permanently magnetic discs to control fuel flow through a main metering orifice and air flow through an idle air bleed.

Abstract: The idle and main fuel passages of a carburetor are controlled by metering apparatus which is regulated to maintain the idle and part throttle air-fuel mixtures at a selected air-fuel ratio, but during low temperature engine operating conditions the part throttle mixture is leaner than the idle mixture in any particular regulated mode of the metering apparatus. This invention provides a mixture forming assembly which further includes means for leaning the idle mixture only during such low temperature operating conditions; the metering apparatus is then regulated to a rich mode at idle during low temperature engine operating conditions to provide an idle mixture which is leaned to the selected air-fuel ratio, and a lean part throttle mixture is avoided as the throttle is opened from idle to a part throttle position.

Abstract: A switching member simultaneously establishes a reference pressure and selects the pressure in one of two zones of a recirculation passage to create a control pressure, and a transducer regulates an operating pressure which positions a control valve to provide exhaust gas recirculation at rates which establish the pressures in the zones necessary to maintain the control pressure equal to the reference pressure. Exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is a proportion of induction air flow with the proportion being ruled by the switching member.

Abstract: A transducer modifies a subatmospheric pressure signal to create an operating pressure which positions an exhaust gas recirculation control valve. A regulating unit senses subatmospheric induction passage pressure to provide the pressure signal and prevents the pressure signal from dropping below a lower limit to thereby establish the maximum exhaust gas recirculation area produced by the control valve.

Abstract: In a dual displacement internal combustion engine which operates on four cylinders at selected times and eight cylinders at other times, the air induction passage creates a subatmospheric pressure signal which is higher during the four cylinder mode than during the eight cylinder mode. An exhaust gas recirculation control valve is operated from that pressure signal, and a solenoid valve opens a port from the atmosphere to increase the pressure signal when operating on eight cylinders to provide similar operating pressure under both modes of operation.

Abstract: A transducer creates an operating pressure that positions a control valve to provide exhaust gas recirculation at rates which maintain the control pressure in the recirculation passage between the valve and an orifice equal to a reference pressure; exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is substantially proportional to induction air flow. The transducer also varies the reference pressure inversely with exhaust backpressure, thereby causing a reduction in the control pressure and a corresponding increase in the proportion of exhaust gas recirculation to induction air flow upon an increase in induction air flow.

Abstract: A carburetor controlled by a pulse width modulated duty cycle operated solenoid has a main metering rod and an idle bleed valve spring biased against a bracket carried by the solenoid armature. The armature is spring biased to a rich position against an adjustable stop and is pulled by the solenoid coil to a lean position against a portion of the solenoid coil assembly. The entire coil assembly is spring biased against a stop which is adjusted to establish the lean position of the metering rod and bleed valve.

Abstract: In a carburetor, an electromagnet energized according to a pulse width modulated duty cycle has a stationary pole member which drives a pair of magnetically responsive valves--one or both being permanently magnetic--to control fuel flow through a main metering orifice and air flow through an idle air bleed.

Abstract: A transducer regulates an operating pressure which positions an exhaust gas recirculation control valve pintle to provide exhaust gas recirculation at rates which maintain the pressure in the recirculation passage upstream of the valve pintle equal to a reference pressure; exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is substantially proportional to induction air flow. The transducer has a pair of current carrying coils which create a bias affecting the reference pressure; the current is adjusted for selected operating conditions to change the reference pressure and thereby change the proportion of exhaust gas recirculation to induction air flow.

Abstract: A turbocharged internal combustion engine has a carburetor fuel metering control rod, an ignition timing control member, an exhaust gas recirculation control pintle, and an induction air temperature control damper operated in a response to vacuum signals created by the pressure in the induction passage between the throttle and the turbocharger compressor and a valve which bleeds the vacuum signals to atmospheric pressure when the compressor discharge pressure rises above a selected value to establish a rich air-fuel mixture, retard ignition timing, inhibit exhaust gas recirculation and provide cool induction air flow for maximum power operation.

Abstract: Ignition timing and exhaust gas recirculation vary with exhaust pressure over one range of engine operation, while in a second range of operation ignition timing varies with induction passage pressure and exhaust gas recirculation varies with both induction passage pressure and exhaust pressure.

Abstract: A vacuum motor suitable for actuating a carburetor choke valve has primary and secondary stages responsive to separate vacuum signals. The secondary stage is carried by the primary stage and has a valve which opens upon full retraction of the primary stage to permit application of a vacuum signal to the secondary stage.

Abstract: A system for positioning an engine control element has a sensor measuring a value corresponding to the actual position of the element, a reference providing a command value establishing the proper position for the element, an electronic control which compares the measured value with the command value, and an actuator including a fluid pressure responsive motor for moving the element and a pressure regulator directed by the electronic control to regulate the fluid pressure delivered to the motor and cause the motor to move the control element to the proper position. The pressure regulator has a coil energized by the electronic control and a valve member which floats between a regulated-pressure-reducing bias caused by the magnetic flux created in the coil and a regulated-pressure-increasing bias caused by a varying but uncontrolled pressure differential.

Abstract: In an engine having a pump for delivering air to the exhaust system to support oxidation of exhaust gases, a valve opens when air delivered by the pump exceeds a selected temperature to bleed air from the pump into the vacuum chamber of a diaphragm operated valve. In one embodiment the valve diverts air from the exhaust system to relieve the backpressure on the pump, while in another embodiment the valve closes an exhaust gas recirculation passage to improve efficiency of operation.