Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
OK, When you first turn the ignition on I don't hear the pump kick in wiht the relay removed but do with it istalled. It also continues to run wihte hte relay installed.
When the ignition switch is turned "ON", the Electronic Control Module (ECM) will turn "ON" the in-tank fuel pump. It will remain "ON" as long as the engine is cranking or running, and the ECM is receiving distributor reference pulses. If there are no reference pulses, the ECM will shut "OFF" the fuel pump within 2 seconds after ignition "ON" or engine stops except when a fuel module is used.The pump will deliver fuel to the TBI unit where the system pressure is controlled to about 62 to 90 kPa (9 to 13 psi). Excess fuel is then returned to the fuel tank.A fuel module is used on all 7.4L, G van with 5.7L, and all other 5.7L over 8500 GVW engines to correct a hot restart (vapor lock) during a high ambient condition. It is designed to over-ride the ECM two second pump operation and will run the fuel pump for twenty seconds at initial ignition "ON".
try these specs on the ecm too
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank. This chart should be used on engines using the Model 220 throttle body.
If no trouble is found in the fuel pump circuit or ignition system and the cause of a "Engine Cranks But Will Not Run" has not been found, check for:
need help on a 1999 Chevy K3500 pickup with a 7.4 L