Join Date: Nov 2000
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Re: First problem w/Howell TBI, No Fuel at injectors..
The fuel injection system you have works on what is known as Speed Density. Speed is determined by rpms as sensed from the ignition module pulses to the coil, and density from the MAP (manifold air) pressure sensor in the intake manifold (or on the ecu). That calculation plus sensor inputs, calculates the amount of fuel required by the engine. The ecu won't deliver fuel to an idle engine. Unless the ignition system works and delivers pulses to the ecu, its "internal tachometer" reads zero, and delivers no fuel. The pulses that open the injectors are timed to the ignition pulse, their duration is determined by the ecu's speed density calculation. So as said earlier, no spark equals no squirt.