Symptom: Abrupt stall at freeway speed. Will crank, but fuel pump not activating. No pump sound after tapping start button.
Everything independently tests OK. What am I missing?
1) Testing for a broken sending unit ground wire. Made a ground jumper from base of sending unit to frame, tapped start button. and fuel pump does not start.
2) Tested voltage at sending unit harness supply side (green wire female) by tapping on start button. Reads 12.5 volts for a 1.5 seconds.
3) Removed fuel pump and did a bench test. Works fine. Sounded a little growly when coming to a stop.
4) Removed sending unit and bench tested for continuity. Green wire at harness male post has continuity to dirty yellow hot wire to pump. Brown wire at harness has continuity to black ground wire to pump. I tried wiggling the wires and was able to maintain continuity. Both A-OK.
5) Trying to isolate sending unit harness by reconnecting sending unit to harness, tapping start button and reading voltage at pump connection wires. Runs up to 12.5 v and back down. Harness connection seems to be working.
6) Removed fuel filter and will replace. I have yet to give it a blow test. It was replaced about 40k ago.
Full disclosure, I cleaned ignition and kill switches prior to this failure. Had about 10 successful starts and runs prior to failure. I’m thinking this is not related.
What am I missing? Can someone explain exactly how you get 1 - 2 seconds of voltage to the pump by tapping the start key? In other words what supplies voltage for that short period of time when the starter has stopped and K75 not running? I’m just curious.
Without feedback I’m inclined to replace filter and pump and keep the current pump as a spare. Feels strange to not find anything obviously wrong.
Due to fire danger home power shut off I won't be able to check for possible responses until tomorrow afternoon at the earliest.
Thank you in advance,
Pete
Everything independently tests OK. What am I missing?
1) Testing for a broken sending unit ground wire. Made a ground jumper from base of sending unit to frame, tapped start button. and fuel pump does not start.
2) Tested voltage at sending unit harness supply side (green wire female) by tapping on start button. Reads 12.5 volts for a 1.5 seconds.
3) Removed fuel pump and did a bench test. Works fine. Sounded a little growly when coming to a stop.
4) Removed sending unit and bench tested for continuity. Green wire at harness male post has continuity to dirty yellow hot wire to pump. Brown wire at harness has continuity to black ground wire to pump. I tried wiggling the wires and was able to maintain continuity. Both A-OK.
5) Trying to isolate sending unit harness by reconnecting sending unit to harness, tapping start button and reading voltage at pump connection wires. Runs up to 12.5 v and back down. Harness connection seems to be working.
6) Removed fuel filter and will replace. I have yet to give it a blow test. It was replaced about 40k ago.
Full disclosure, I cleaned ignition and kill switches prior to this failure. Had about 10 successful starts and runs prior to failure. I’m thinking this is not related.
What am I missing? Can someone explain exactly how you get 1 - 2 seconds of voltage to the pump by tapping the start key? In other words what supplies voltage for that short period of time when the starter has stopped and K75 not running? I’m just curious.
Without feedback I’m inclined to replace filter and pump and keep the current pump as a spare. Feels strange to not find anything obviously wrong.
Due to fire danger home power shut off I won't be able to check for possible responses until tomorrow afternoon at the earliest.
Thank you in advance,
Pete