87 325 Fuel pump issue

03/87 325

No voltage to external pump. Relay was bad = replaced.

With wires disconnected from pump and starting = 10 vdc on the two pump wires.

When wires connected to pump and starting = 0 vdc???

12 vdc directly to pump from battery and pump runs.

Internal tank pump is OK.

UPDATE: Now no pwr. at pump when starting. Relay still ok. Is there more than "1" relay involved? Poor Haynes book in hand.

MORE Update: Main relay stays energized with key OFF. F11 reads 0.5 vdc with key on. No continuity from 87 to pump

Any clues?

Thanks,

Fratz

You have a voltage drop caused by high resistance in the wiring somewhere.

you have a "Main Relay" and a "Fuel Pump Relay" and fuse ? 17 I think...........anyway, the pump relay has 4 connectors one of which will have two green/violet wires coming off it. The Main Relay has 5 terminals with large red, red/white and red/blue wires coming off it. Replace Both relays and see what you have.........also replace the pump fuse, just can't remember it's number.........F11?........F17?..........jb.

crash8186 / Jeffrey,

Thanks for the replies.

Found the 87 line splice that branches to both pumps under the rear seat had failed/burnt.

My 325 has been resurrected from the dead.

Last question: The fuel pump main relay stays energized with the key OFF. It appears to get it's ground from the MCU. Normal?

Again...thanks for the assist.

Fratz

The Main Relay IS energized with the key in start or run..............the Fuel Pump Relay should ONLY be energized in START or with the engine RUNNING !....[should not be energized with the key on, engine off !]