Archived J-Fet controller lift pump

[2-ND TIME]

Electronics Question.





Well the drive down wasn't pleasurable at all and the driving in Victoria was even worse. (driveability wise) Victoria was good as usual.

The J-Fet that controls the lift pump why would it stay on duty cycle and not go to run mode when the engine is warm or is it warm? What might this say? The duty cycle load ??? is seen into the PDC and not the alternator or the batteries which have been replaced. This is upsetting the ECM electronics and causing it to misfuel ??? What might cause the j-fet to stay on duty cycle?



Buy Cat Power



The APPS stayed reset for less than 2 months and the 3 key reset method worked to reset it. :--) Have more power but bucks terribly.

 

[AKAMAC]

I'll bite. What is a j-fet? What is the lift pump doing during the "duty cycle"? What year truck? Mike

 

[2-ND TIME]

The info for the rest of what I should have included. J-Fet Is junction field effect transistor. Duty cycle is the time period that it is turned on for . I am surmising that it is causing the loading of the ECM.



Mom was telling me that I had to hurry up and go for my brother inlaw's birthday dinner so I missed because the log in at the first didn't accept my log in.

This is for a 99 24V 3500 4x4 5 spd.

 

[AKAMAC]

The "FET" is a transistor that manipulates current. On a DC system, voltage is usually used to control motor speed. The lift pump, as I understand it, runs at constant voltage/speed. The only thing the ECM does is run it momentarily during start up.



Try checking for codes, fuel pressure. A LP going bad will often run intermittently as it gets warm.



I still don't know what the "Junction-FET" is.



Sorry for the lag time in response, I forgot about the post I made. Mike