thomasr

HI

My car swings but wont start. It has been standing for about a year or so. It was driving then parked. Now it just swings.

There is only 1.7 v at the fuel pump in the boot.

The relay no 372 does trip and has continuity.

The fuse I assume no 28 also has low voltage.

yet at the relay there is 12V

Any suggestions please what to check for

twentysevenlitres

If functioning correctly, the fuel pump power supply will only get 12V for around 2 secs when ignition is switched to the 'run' position for the first time after a shut down (key removed from ignition, may even need to lock the car or wait a couple of minutes between attempts), and then again during engine crank. It will only get a continuous 12V after it starts (after start relay).

To check the condition of the fuel pump, you will need to run a bypass from the battery +ve terminal to the pump side of the fuse (remove fuse), or even directly to the pump. When trouble shooting in this way, I often put a toggle switch in the wire to give me a bit more control over the power.
Once you establish whether the pump is physically running or not, a backyard pressure test (flow test) can be done to establish its health. This involves removing the fuel return hose from the low pressure (return) side of the fuel pressure regulator at the end of the fuel rail (1.8's in the B5 chassis may have a pipe off the low pressure side of the regulator that goes about half way back up the engine) and running a short bit of hose into a suitable container. Run the pump for around 15 secs, you should get 600-800ml of fuel (about 20 ounces or 2/3rd of a quart).
Be sure to test the return line from the fuel pressure regulator, this ensures the pump has to pressurise the fuel rail (4 bar/60psi) before filling your container.

After sitting so long, it will pay to do some preventative things like change the fuel filter, and if you didn't put fuel stabiliser in the tank before it sat, get some fresh fuel in there at the very least - drain it if necessary! If you're using an ethanol blended fuel, sugars can crystalise after that much time and cause some dramas...

turbo510

If you have 12V at the fuel pump pin of the relay (terminal 87 I think) when the relay is activated, but very low voltage at the fuse and fuel pump, then there is high resistance somewhere between the relay and the fuse. These being close together under the dash, should not be too hard to find. Pay attention to the connector condition of both the fuse and the relay socket.

When you say that there is 12V at the relay, do you mean the terminal 30 socket in the relay plate? Have you taken the plastic cover off the relay, plugged the relay back on the relay plate, and actually measured the voltage at the contacts, both open and closed? You could have a burned contact, in which case that can be polished.