When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Fuel System Description Fuel Pump Electrical Circuit When the ignition switch is in the ON position before engaging the starter, the PCM energizes the fuel pump relay for 2 seconds, causing the fuel pump to pressurize the fuel system. If the PCM does not receive the ignition, reference pulses with the engine cranking or running within 2 seconds, the PCM shuts OFF the fuel pump relay, causing the fuel pump to stop. Starting Mode With the ignition switch in the ON position, before engaging the starter, the PCM energizes the fuel pump relay for 2 seconds allowing the fuel pump to build up pressure. The PCM first checks speed density, then switches to the mass air flow (MAF) sensor. The PCM also uses the engine coolant temperature (ECT), throttle position (TP), and manifold absolute pressure (MAP) sensors to determine the proper air/fuel ratio for starting. The PCM controls the amount of fuel delivered in the starting mode by changing the pulse width, or the On time, of the injectors. As your car has Long crank on cold start WITH less than quarter tank in gas, this could be an indication that you are losing the static fuel pressure in the fuel feed system over the time the car is parked. Couple of tests you can do to see if you are losing the static fuel pressure with the fuel pump OFF and not activated. 1. Loosen the fuel filler cap in order to relieve the fuel tank vapor pressure. 2. Remove the left fuel rail cover. 3. Connect a fuel pressure gauge to the fuel pressure connection. Wrap a shop towel around the fitting while connecting the gauge in order to avoid spillage. With the ignition switch, cycle the key from OFF to ON position (NOT START) to pressurize the fuel feed system. Repeat this step 5 times to build fuel pressure. Record fuel fuel pressure on gauge which should be around (55-62 psi). Important: The fuel pressure may vary slightly when the fuel pump stops running. After the fuel pump stops running, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute. If the fuel pressure drops more than (5 psi) then you have a leak in the fuel feed system. Components that could cause loss of fuel feed system pressure with fuel pump off (static fuel pressure drop). Leaking fuel injector(s) > risk low, no DIC codes indicating engine running rich correct? But you can isolate the injectors by disconnecting the main fuel feed line from the injector rail and connect fuel pressure gauge, perform test to see if the fuel pressure drops. Sticking fuel feed checkvalve> risk high. On the Left fuel tank there is a fuel feed pipe that has an integral checkvalve in order to maintain the fuel system pressure in the feed pipe with the fuel pump OFF. Unfortunately the checkvalve is not replaceable by itself. The rear fuel feed pipe has an integral checkvalve in order to maintain the fuel system pressure in the feed pipe and if this checkvalve is unserviceable, you will have to replace the fuel feed line. Cheers , Goose
Fuel System Description Fuel Pump Electrical Circuit When the ignition switch is in the ON position before engaging the starter, the PCM energizes the fuel pump relay for 2 seconds, causing the fuel pump to pressurize the fuel system. If the PCM does not receive the ignition, reference pulses with the engine cranking or running within 2 seconds, the PCM shuts OFF the fuel pump relay, causing the fuel pump to stop. Starting Mode With the ignition switch in the ON position, before engaging the starter, the PCM energizes the fuel pump relay for 2 seconds allowing the fuel pump to build up pressure. The PCM first checks speed density, then switches to the mass air flow (MAF) sensor. The PCM also uses the engine coolant temperature (ECT), throttle position (TP), and manifold absolute pressure (MAP) sensors to determine the proper air/fuel ratio for starting. The PCM controls the amount of fuel delivered in the starting mode by changing the pulse width, or the On time, of the injectors. As your car has Long crank on cold start WITH less than quarter tank in gas, this could be an indication that you are losing the static fuel pressure in the fuel feed system over the time the car is parked. Couple of tests you can do to see if you are losing the static fuel pressure with the fuel pump OFF and not activated. 1. Loosen the fuel filler cap in order to relieve the fuel tank vapor pressure. 2. Remove the left fuel rail cover. 3. Connect a fuel pressure gauge to the fuel pressure connection. Wrap a shop towel around the fitting while connecting the gauge in order to avoid spillage. With the ignition switch, cycle the key from OFF to ON position (NOT START) to pressurize the fuel feed system. Repeat this step 5 times to build fuel pressure. Record fuel fuel pressure on gauge which should be around (55-62 psi). Important: The fuel pressure may vary slightly when the fuel pump stops running. After the fuel pump stops running, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute. If the fuel pressure drops more than (5 psi) then you have a leak in the fuel feed system. Components that could cause loss of fuel feed system pressure with fuel pump off (static fuel pressure drop). Leaking fuel injector(s) > risk low, no DIC codes indicating engine running rich correct? But you can isolate the injectors by disconnecting the main fuel feed line from the injector rail and connect fuel pressure gauge, perform test to see if the fuel pressure drops. Sticking fuel feed checkvalve> risk high. On the Left fuel tank there is a fuel feed pipe that has an integral checkvalve in order to maintain the fuel system pressure in the feed pipe with the fuel pump OFF. Unfortunately the checkvalve is not replaceable by itself. The rear fuel feed pipe has an integral checkvalve in order to maintain the fuel system pressure in the feed pipe and if this checkvalve is unserviceable, you will have to replace the fuel feed line. Cheers , Goose
Great write up. Thanks. Does the issue only happening when the tank is close to empty change this analysis? I don’t see any mention of that in the cut and paste. Thanks!!!
Great write up. Thanks. Does the issue only happening when the tank is close to empty change this analysis? I don’t see any mention of that in the cut and paste. Thanks!!!
tank being close to empty does not change the troubleshooting procedure...
Step 1 remove the fuel tank cap...this step release any vapor pressure in the tank that you may have. Removing head pressure on the fuel in the tank.
empty tank iess fuel to to create a head pressure on the fuel in the tank.
cheers
Goose
Thanks!! I had a hunch that it was the fuel feed line with the check valve so I picked up a used one (new is discontinued unfortunately). I’m always a little nervous using used fuel lines though.
Last edited by Chogan835; Feb 17, 2021 at 10:17 AM.
Cold start issue
