1992 Volvo 740 wagon

[lemon11]

Hi everyone!

My name is Ruth & I'm new on this site. I have 2 Volvo's, so of course I have a question or two! This one is about a 1992 740 Volvo wagon:
The fuel pump is not running. Fuses check out ok. Motor on pump has resisitance. I found the control relay on the panel center console & it seems to be working when the ignition is on. The relay is small and the low current type.
Is there another heavy duty relay to handle the pump current? If so, where is it located?

Thank you TONS!!!!!!!

--Ruth

[billofdurham]

Welcome to Matthew's Volvo Site.

Which fuel system is fitted, the LH 2.4 or the Regina? The LH 2.4 has two fuel pumps, one in-tank and a main under the car. The Regina has one pump in the tank.

On the LH 2.4 there is another relay in the engine compartment. It is called the radio suppression relay but is a fuel injector relay. In 1986 Volvo decided to isolate the fuel injector circuit because of some radio interference created by the pulsing circuit. The solution was to energize a relay, the radio suppression relay, with the pump/system relay feed instead of using it to power the injectors directly. The radio suppression relay then supplies the + power to the injectors. The timed earth (ground) comes from the Engine Control Module. For the most part the non-turbo engines had the radio suppression relay mounted on the passenger side of the engine compartment on or near the coolant reservoir. The turbo engines had the radio suppression relay mounted on the driver's side of the engine compartment on or near the shock tower. The radio suppression relay was used from 1986 until 1995 on almost all LH injected 4 cyl and V6 engines. There may be a couple of exceptions. When it's bad or missing, the radio will work fine, but the engine will not run. Remember, even though it's called a radio suppression relay it's function is to supply + power to the fuel injectors.

If you suspect that your radio suppression relay is faulty try switching the leads with the electric cooling fan relay if your car has one. This relay is identical and is often located right next to the radio suppression relay. If your fan stops and your engine starts, then you've isolated the problem.

Bill.