Sierrasideways

iTrader: (1)

Ahoy there fellow fanatics,

We've rewired a new 044 fuel pump to my Saff and it's not working properly. Voltage at the battery is 13.3V, voltage at the pump at idle 900rpm is 11.8V. Haven't tested it under load as this value is wrong to begin with.

I have followed the main threads here on how to do it. They look simple but some numbnuts went at the wiring before and it's a faacking mess, to say the least.

Anyway my confusing problem is this:

New 2 core 25Amp wiring going from + battery to 25A blade fuse to 12V in of relay ( 5 pin relay 30A ). - to ground of relay.

12V out of relay going to + of fuel pump.
Ground of pump going to relay and then to battery as above.

My problem is the trigger wire. We tried using the old black and red wire ( old fuel pump feed + ) going into old yellow relay. Cut this wire and used it as the trigger on the new relay - no good, car wouldn't start.

This is what it says in the diagrams and loads of threads on here. It won't work on my car for some reason. Also there are 2 other live wires feeding into the old yellow relay so I'm thinking the black and red wire needs this power to turn on, not sure though.

Anyway the only bloody way it will work is by connecting the old yellow fuel pump relay, connecting the new fuel pump relay also and breaking the black and red wire and then plugging it in from the old yellow relay to the new trigger pin of the new relay.

Upon doing this, the car now starts arseways when cold and I have to keep the foot down or else it will cut out. When it warms up its ok and idles fine.

Tried following the simple diagrams on here but to no avail like above.

Where are we going wrong?

For something so simple I just don't get it...

Could it be the rats nest messing something up?

I can't take the car to the rolling road now as I only have 11.8V at the pump at idle.

Cheers, hope someone can help!

Philip.

mark r

why don't you just run a new switching wire into relay from ecu plug or from old yellow relay bypassing old yellow relay and check your negative connections as it don't matter if you use the old trigger wire the volts reading should be good as voltage carried on new feed and relay

mark

Sierrasideways

iTrader: (1)

Hi Mark R,

Do you mean run a live wire from old yellow relay?

We didn't want to do this as we didnt know what the live wires on the old relay were for. I know it's the fuel pump relay but still we thought they could be used for more than one function hence why we didnt use them.

Or am I wrong and can we take any wire from they old relay and use it as a constant feed going into the trigger in the new relay? That way, the old relay would be discarded.

Is that what you mean?

A constant feed from an ECU pin would be handy but don't want to go disturbing it as haven't taken it out before and if I move something, it is bound to go wrong, like everything else so far!!!

Cheers.

Sierrasideways

iTrader: (1)

Bump

What pin from ECU would be suitable for a switching wire?

Turbosystems

iTrader: (5)

pin 28 or pin 10

Sierrasideways

iTrader: (1)

Cheers mate. Will update this when I get it sorted.

Philip.

mark r

you need to find the switched wire from ecu,as tony has told you either pins you can use as a new trigger wire/switch line for new relay.this will sort you out and will discard old wiring

mark

opposite lock

iTrader: (3)

I would earth the pump direct to battery. Then an 12v ignition feed from the the o.e setup turning on your new pump relay which is fed 12v+ fused direct from battery as you have already.
The o.e live pump wire should be ample to switch a relay on .

Stu @ M Developments

iTrader: (12)

Your fuel pump used to have a live going to it as per factory install. Its this wire you use to activate the new relay.
Leave all the yellow relay wiring behind dash EXACTLY as it was because it powers more than just your fuel pump.

tonyRS

I never went anywhere near the yellow relay, all wiring was at back of the car, used original feed to "trigger" relay