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3. A fuel system that drops more than 34 kPa (5 psi) in 10 minutes has a leak in one or more of the following areas:
^ The fuel pump check valve.
^ The fuel pump flex pipe.
^ The valve or valve seat within the fuel pressure regulator.
^ The fuel injector(s).
4. A fuel system that drops more than 14 kPa (2 psi) in 10 minutes after being relieved to 69 kPa (10 psi) indicates a leaking fuel pump check valve.
5. Fuel pressure that drops-off during acceleration, cruise or hard cornering may cause a lean condition. A lean condition can cause a loss of power, surging, or misfire. You can diagnose a lean condition using a scan tool. If an extremely lean condition occurs, the heated oxygen sensors(s) will stop toggling. The heated oxygen sensor output voltage(s) will drop below 300 mV. The fuel injector pulse width will increase.
so I checked the pressure again. From static, pump off, it drops 8 psi in 7 minutes. Did go to 58 psi on wide open throttle. Both actual throttle and pulling vacuum hose from regulator.
Changed the fuel filter and fuel pressure regulator. Same result on all pressure tests. Still drives at +35-40% trim.
From your references, i guess i have a leak somewhere. Either check valve at the pump or in the fuel injectors.
Regarding the fuel injector balance testing/results, I have zero experience in this area.
Regarding the pictures of the spark plug(s), what I see sure looks like a way too wide gap.
According to the information off of rockauto.com, the factory recommended spark plug is the ACDelco 41-962 double platinum plug, and the factory recommended gap is 0.040". I do know that the Vortec engines are really picky about which spark plugs they like, so be sure and go with ACDelco 41-962 double platinum plugs. Also, do not purchase them from Amazon or ebay as they will likely be counterfeit plugs. If you want to save a few bucks on plugs, purchase them from rockauto.com as they use the same auto parts warehouses the brick and mortar parts stores use.
If you purchase new spark plugs, DO NOT check the gap or attempt to regap them. They come pre-gapped from the factory and if you try to check/adjust the gap, you can easily damage the precious metal coating on the electrodes as it is extremely thin.
Regarding the fuel injector balance testing/results, I have zero experience in this area.
Regarding the pictures of the spark plug(s), what I see sure looks like a way too wide gap.
According to the information off of rockauto.com, the factory recommended spark plug is the ACDelco 41-962 double platinum plug, and the factory recommended gap is 0.040". I do know that the Vortec engines are really picky about which spark plugs they like, so be sure and go with ACDelco 41-962 double platinum plugs. Also, do not purchase them from Amazon or ebay as they will likely be counterfeit plugs. If you want to save a few bucks on plugs, purchase them from rockauto.com as they use the same auto parts warehouses the brick and mortar parts stores use.
If you purchase new spark plugs, DO NOT check the gap or attempt to regap them. They come pre-gapped from the factory and if you try to check/adjust the gap, you can easily damage the precious metal coating on the electrodes as it is extremely thin.
thanks for the info. I'll try to get some new olugs in there and see if it helps. Not sure if it will effect fuel trim though.
June 19th, 2024, 1:48 PM
