mk6matt_1992

Right.....
Basically i've been working on my project car for quite some time now and i'm having a bit of trouble with the wiring. The problem is that i cannot get power to my fuel pump, there is a constant live into the relay (which is brand new) but i cant get a feed out to the fuel pump. I have checked all corresponding wires go to the fuel pump relay and they are all wired as they are supposed to be ????????????? i was wondering if the fact that the amplifier pack to the coil isn't connected at present if that is preventing the pump from powering up. If anyone has any information on this and/or wiring diagrams for the amplifier pack as someone decided it would be a clever idea to remove the multi plug connectors and all i have are five bare wires
chers matt

martysmartie

iTrader: (1)

A relay in most cases and indeed this one needs two lives, one is a permanent live, and the other a switched live, the permanent will be the feed to the pump when tripped, and the other is for the relay itself. The forth wire should be an earth, in the case of the RST I believe this goes to the ECU and is grounded upon recieving ignition pulses, it also primes for five seconds when the ignition is switched on.

You need to make sure the relay is activating first, it should click if so, if it does not then you need to check the switched feed to it, and the earth is good.

As a last result as a test ONLY you can temporarily bridge the relay input and output, I.E the permanent live and the output wire which will go to the pump itself, when you do so the pump should run permanently, if it doesen't then you have either a pump fault or it's associated wiring.

Martin

mk6matt_1992

Thanks martin, been tinkering with it today and there is no switched feed going to the relay, everything seems to be in the right place (after checking for the millionth time lol). I did have a spare air/fuel ECU knocking around my garage so i did try the spare one incase the existing unit was at fault however this made no difference. Was wondering if you had any more advice as im only 19 and don't have a vast knowledge of auto electronics. Any help appreciated
Matt

martysmartie

iTrader: (1)

Then thats why, your relay needs to have two power feeds, one is the one which will feed the pump, (Should be identifiable by having thicker wiring) and the other is the feed to the relay itself which energises it, you then have an output from the relay which will be your pump feed and the other will be an earth.

As a test you could bridge the feed you do have (What will be the pump feed) to the other terminal where the second live you are missing should be, do so with the ignition ON this should power the relay and pump priming should commence. You then know it's all working ok so you just have to find why the second feed is missing.

Martin

tabetha

Assuming it's a std relay, look on the bottom of it, you will see some numbers, now bridge the 30(battery input), and 87(relay output) to determine the pump actually works.
If it is one of the dodgy std mfi used relays I'd just replace it with a fuel cut off from a later efi car(mondeo/escort etc) and wire it permanent to the ignition live to a new relay, the system has a pressure return so this is no biggee, and with the cut off is safe.
tabetha