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

parts counter with many trips to the car to get all the right connectors with the different size
ends. Only one connection at the port is made with a section of straight vacuum hose with equal
size at each end! My feeling is that getting connectors with the right size ends is important for
reliability. When rubber is over stretched is starts cracking real soon. If the connection is loose
the obvious will happen.
Fuel Pump and FI Relay Diagnostic Tests. Here is a procedure to test the operation of the
fuel injection relay and the operation of both fuel pumps. The 3 main things to check in the fuel
circuit are the fuel pump relay, and the 2 fuel pumps.
1. Fuel Injection Relay Test. There are 2 relays inside the fuel injection/pump relay. One
of them should turn ON when the ignition is turned on (without turning over the engine),
and the other relay (which actually turns the fuel pumps) should come ON when the
engine turns over/runs. You can check the 1st relay by putting your fingers on the relay
module and turning the ignition on and off repeatedly. You should feel the relay click on
every time. If it doesn't, that relay isn't working. And you'll find the car doesn't start if the
relay did not come on.
[Tip:] To check for possible fuel pump relay failure go between center of cig lighter plug
and fuse 11, should be less than .5 V (