No power to fuel pump?

Post by **Southbay850** » 24 Jan 2013, 00:22

Hello Volvo enthusiasts. I have a 1990 740 turbo automatic that has been giving me grief. I have been troubleshooting a no start issue. To make a long story short I have not heard the fuel pump coming on when I turn the key on.(turn key w/o starting) I pulled the pump that is under drivers side that is beside a fuel filter and tested it. (Not the in tank) When connecting it to a 12v battery it starts right up and sounds strong. After reinstalling it I tried to start the car again no luck. Next thing I tried was pulling the relay and jumping the terminals still nothing. Do you think there is something wrong with the wires to the pump? There are 2 a black and a pink. One more thing I have checked the fuses and tried 3 different relays.

Post by **billofdurham** » 24 Jan 2013, 12:08

Is fuel reaching the engine? Crank the engine and remove a spark plug. If fuel is getting there the plug will be wet. If the plug is dry check the noise suppression relay in the engine compartment. It is mounted on the driver's side strut tower.

A quick check can be made by switching it with the cooling fan relay which is mounted in the same area.

The noise suppression relay controls the injectors.

Bill.

Post by **Southbay850** » 27 Jan 2013, 22:58

Thanks Bill I will go try that again now. I pulled my injectors and the rail to clean them out. I noticed that I was getting fuel to the rail but not the injectors. I pulled a 144 on the obd and it said it was a fuel load problem. I ran it through the self diagnose and hear them make a spray noise but not convinced that all are working. Pulled the plugs they are dry. Tested the spark all 4 are firing. One thing that I am noticing is the amount of air pressure hissing out of the coolant tank that has the grey cap. Maybe unrelated? F.Y.I. It is a 1990 740 turbo.

Post by **billofdurham** » 28 Jan 2013, 11:47

Did you erase the code? That code will put your car into 'limp home' mode. I always erase codes and try the car to see what happens. Spurious codes are common place on the OBD 1 system.

The radiator cap is probably failing. See the topic pinned at the top of the forum on that subject.

Bill.

Post by **Southbay850** » 01 Feb 2013, 18:20

Tried everything that has been suggested. I am getting fuel + spark but no start. It wants to but it just wont give.