crisis in the fuelpump

[ochten]

My fuelpump stops working. Checked the fuse (fuse 34 is OK) no power at all on fuse 34 . Changed the relay for a new one, no result. The startermotor turns and I have a ign. spark Is the immobiliser or the ECU suspect?
What feeds the yellow wire to the fusebox?

[froggie]

i think there's a power from the ECU,TO THE RELAY not sure which, it sends a signal to relay to run the pump for so many seconds when the ign is first turned on ,then again when the engine is turning.there's a diagram on one of the tvr manual type sights
Have you tried jumping the relay over with a piece of wire? the diagram is usually on the side of it.

[ochten]

On the pumprelay (number 90378651)are 6 connections (86 30 85 85b 87 and 87b) What numbers I have to "hotwire"to test the powersupply?

[GreenV8S]

ochten said:

On the pumprelay (number 90378651)are 6 connections (86 30 85 85b 87 and 87b) What numbers I have to "hotwire"to test the powersupply?

The relay socket will probably look like this:



The insides of the relay are connected like this:



I suggest you start by checking whether the relay is operating when the ignition is switched on (typically the pump will only operate briefly each time the ignition is switched on).

This confirms that you are looking at the right relay, and also confirms that the control side of the relay and associated wiring is OK.

If the relay isn't operating, check out the control side. You should see 12v between terminals 85 and 86 to operate the relay. If you haven't got that, see whether it's the 12v or earth that is missing.

If the relay IS operating then check out the switched power side. You should have 12v on terminal 30, and terminal 87 (or 87a) should be connected via the pump to earth. You can test this electrically by measuring the resistance from here to earth(should be a few Ohms). If you have a circuit to earth, and have 12V on terminal 30, then you can hot-wire the relay by putting a fused link wire between terminals 30 and 87/87a. You can make up a fused link wire very easily using a couple of short pieces of wire with a male spade connector crimped on one end and female crimped on the other. The male spade push into the relay socket; the females push onto an ordinary automotive blade fuse.

[ochten]

Thanks for the help. Strange is that the pump is not running at all, even if you switch the ign. on. With pressing the key ( "alarm off" ) I could "activate"the pump (ignition on) for 5 seconds but now it is complete dead. Could it be that the immobiliser or the alarm unit are not given the first signal to the relay or the fuse box?
What comes first; the immobliser sends first a signal to the relay and then the fusebox?

[froggie]

if imobaliser is not working engine willnot turn over,

pumps usualy work intermitent when they are breaking down.

can you feel the relay (brown)click when ign is turned on/off?

try a bulb across pump conections,should only light for a few seconds when ign turned on

try a 12v fused suply direct to the pump after disconecting from car

WWW.MYTUSCAN.UK has wiring help in downloads section i think

[jeast]

Isn't there an inertia switch in the boot that switches off the fuel pump in an accident? - could be worth trying to reset.

[froggie]

its in the centre above the fuel tank behind the carpeting. or under the nearside dash on a mk3.me thinks just press the rubberised top to reset if its triped.

[ochten]

I tried to test tonight the system with the help of the famous Carl Baker on the phone .(he is a very helpfull bloke!) It seems to be that the pump-relay (is new) is not working at it should be .(no ground on the relay) We are not sure that the ground of the relay should come from the main-ECU.
Tomorrow I will test the wire from port no 87 of the relay to the fuelpump with a direct feed.
It could be that I have a broken wire somewhere. I will also "hotwire"the Internia to be sure.
It takes a long time to find out because you can play with a lot of possibilities.
The immobiliser is OK (according to Carl Baker) the sparks are sparking and the starter-engine is running. Only a dead fuel pump! (when I feed the the fuelpump direct it is running)
I'm glad I'm not middle in the night to find out why the engine is not running.
Will be continued

[froggie]

have you tried to disconect do vis check on ecu conections and replace, i remember a car having a bad conection (think cant remember term 25?)on the ecu fuel pump output

[ochten]

I think it must be the ground connection to the ECU (yellow/black wire) It seems to be that the ECU gives the signal (5 seconds/ingn on) Why it stopped suddenly (last week was the pump running) is strange. I checked all the connections etc but everything is fine. Perhaps I have to send the ECU to Racing Green for a general check.
If I give direct power nearby the fusebox (big connector on top of the fuseboard) the pump is running. But in the relay area something is missing (ground or +)