chrisg

Engine replaced, Air Flow Meter was bad, changed with a new one. Started up and ran well for 3 min. then stopped. Checked all and found that Fuel Pump was not running. Let the engine cool off thought perhaps it was one of the temp. sensors. Did not restart and the fuel pump is not working. Something is telling the ECU that the fuel pump circuit should stay open. I am at a loss. Perhaps someone has seen this problem before and can assist. If U prefer you can email me or call if you have some insight into this particular problem.



Chris

dac

I don't think the fuel pump will run if there is pressure in the rail.



Sounds like you need a fuel pressure gauge to be sure.

j9fd3s

the fuel pump circuit works like this....



on the trigger side: ecu sees the rpm signal -> closes the "circuit opening relay" -> afm switch* -> ground.



on the "power" side: battery ->main relay -> circuit opening relay -> fuel pump



* theres a switch in the afm that OPENS the fuel pump circuit when the afm is 100% closed.