87 325 Fuel pump issue

[Fratz]

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

[crash8168]

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

[jeffreyb4me]

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.

[Fratz]

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

[jeffreyb4me]

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 !]