Hi Paul...Im working on the above engine and its problem mirrors your GM CPI Vortec fuel pump test (Chapter 14,15,16). However for some reason its jump plug to bypass relay - which incidentally is not the plug type but the old fashion 5 - wire type - is not there. How can I bypass the relay to do an amp probe?
The owner tells me that he had been changing fuel pump for at least 9 times in the last 15 years he had this truck. Recently he would spray carbuter cleaner to make it start and he'd go about his driving until recently; put in a new pump that worked for a week and then now a no start low fuel pressure condition (about 43 psi like in your video, same symptons, characteristic and behavior).
robert.lesaca wrote: Hi Paul...Im working on the above engine and its problem mirrors your GM CPI Vortec fuel pump test (Chapter 14,15,16). However for some reason its jump plug to bypass relay - which incidentally is not the plug type but the old fashion 5 - wire type - is not there. How can I bypass the relay to do an amp probe?
The owner tells me that he had been changing fuel pump for at least 9 times in the last 15 years he had this truck. Recently he would spray carbuter cleaner to make it start and he'd go about his driving until recently; put in a new pump that worked for a week and then now a no start low fuel pressure condition (about 43 psi like in your video, same symptons, characteristic and behavior).
You can jump the load side contacts of the relay but just be extra extra extra sure you are jumping the correct pins. If you jump the wrong ones you will cook the ECM driver for the fuel pump relay.
Then check your amperage AND your power and ground at the pump before dropping that tank. If all of that is good, inspect the inside of the tank for debris, inspect the sending unit housing for a bad connection right at the sending unit. Also make sure if it is using an internal fuel pulse dampener that is is in good shape and was installed properly. Then make sure your internal pump hoses are okay. Then final check when you are all done and it has a new pump or whatever, that you check systems psi and make sure that it is not too high, indicating a stuck closed fuel psi reg or plugged return line which will kill your new pump.
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