Wondering if either of the fuel pumps were supposed to prime when the switch is in "on" position on my 85' 240? Right now, I'm not getting prime from either, but didn't know if it is supposed to.

Thanks,
Phil

The engine has to crank to turn on the pumps.

The in the tank pump, feeds the main pump outside the car under the rear seat area. The tank pump is self priming and it has to pump gas, esp. if you are below a half tank of fuel and are trying to go up grade/hill.

The ECU turns on a fuel pump/system relay when it sees a crank signal from the distributor or flywheel sensor.

An easy junction for both pumps power is located under the rear seat cushion on the drivers side. A test meter hooked there it is easier to observe when cranking over the engine.

If thats to hard to get loose you can try to listen under the car for the pump to run. I put a hose in the filler neck and listen for the small tank pump to hum.

"The ECU turns on a fuel pump/system relay when it sees a crank signal from the distributor or flywheel sensor."

The System relay is energized as soon as the key is turned on. The ECU turns the Fuel relay on when it detects timing pulses from the Ignition CU, during cranking and running. The ICU pulses are derived from the distributor Hall sensor on the '85, flywheel sensor on '89 up.

"An easy junction for both pumps power is located under the rear seat cushion on the drivers side. A test meter hooked there it is easier to observe when cranking over the engine."

Easier than struggling with the back seat is to test for voltage first at the Tank pump fuse contact. Probe the LEFT side contact, which gets voltage from the Fuel relay. The voltage at that point is also sent to the Main pump, via the under seat connector.
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.