Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

pump operating without a pre-pump (which would have zero draw).
● If you have an old relay, you can remove the electricals and solder a large wire between
terminals 30 and 87/2. As soon as you put it in (even without the ignition on) the main fuel
pump should start to run and keep running and car should start. If nothing happens, then
your main pump is well dead. Don't forget to remove the relay and chuck it, or mark on it
what you did to it as it would be really dangerous to use otherwise. It is a strictly 'get you
home' or diagnostic.
● So it's your main fuel pump. The tank pre-pump can be dead (or dying) and the motor will
still run if you have more than half a tank of fuel. Get a new one if you can, or a scrap
one from a yard, but test it before you buy it. Order the piece of fuel line from the
accumulator to beginning or main engine line from Volvo.
Changing the Main Under-Car Fuel Pump (Bosch LH Systems):
● Note: If you have a Regina fuel injection system or a later 940 with a single Bosch in-tank
pump, then your pump is inside the tank mounted to the fuel sender unit.
● See the instructions for changing the fuel filter above for tool needs. It helps in the future
to use anti-seize on all bolts and a little dab on the banjo bolts entering the fuel filter.
● Disconnect battery negative.
● Clamp off the front and rear fuel lines using hose clamps. Disconnect both fuel lines to
the pump. The tank-to-pump line has a screw clamp; the pump-to-filter line requires a
17mm wrench with a backup wrench. This short line is fragile, so don't bend or stress it.
Disconnect the filter-to-engine line as above.
● Disconnect the electrical lines by squeezing the connector tangs.
● Drop the cradle holding the pump and filter.
● Remove the fuel filter. Note orientation of filter: flow is toward the rear.
● Turn it over and loosen the bolt securing the filter clamp to the cradle. Remove the filter
clamp.
● Clean out the usually rusted Torx screw in the pump clamp and loosen the clamp.
● Replace the pump. The threaded end goes toward the front.
● Replace the filter clamp and filter.
● Reconnect the pump-to-filter short connector, being careful not to bend it. Use a backup
wrench.
● Install cradle and reconnect the fuel lines.
● Reconnect the electrical lines. Black goes to the black pump terminal.
● Test for leakage.
If you have a one-pump later Bosch or Regina system, see Fuel Sender and In-Tank Pump
Replacement above.
960 Fuel Tank Hose Failure. If your 960 experiences gasoline smells after fillup and occasional
leakage at the tank, see the FAQ section for information about fuel tank hose failures.