s2erst

not sure if my car is meant to do this but as soon as you turn key fuel pump primes like its meant to but keeps on doing it, on my other rs after 3/4 seconds it stops

wedge07

Just supposed to stay on for about 3 secs i think mate?

s2erst

dont know if it makes any difference but its efi not mfi

gtit

you mean its buzzing all the time?mines does it all time really loud, nobody said it wasnt ok wen it got setup?

martysmartie

iTrader: (1)

Yes it does make a difference.

Either the relay is jammed or someone has wired it directly to ground, opposed to the ECU which is what triggers the prime.

Are you using Weber (Cosworth) management?

Martin

jan247uk

ignore this post it was incorrect

Rob_DOHC

iTrader: (4)

Hiya mate,

If it helps standard OFAB/OFAC just primes the pump then cuts out after 2-3 seconds. It sound's like you have a stuck relay or some bad wiring. Earthing the fuel pump wire from the ecu will turn the fuel pump relay on. I take it that it doesn't do this with the ignition off? PM me if you need a hand / wiring diagrams. From memory the main relay feeds 12v to the fuel pump relay, its common for people to bridge the fuel pump relay if they get problems (so its on all the time).


Rob,

s2erst

new relay fitted today still same

tejy

iTrader: (1)

Is it a problem if the fuel pump relay is constantly priming? Mine is

wedge07

Is it an escort with fiesta rst engine fitted, if so it may be wired similar to mine via two yellow relays. It may just be slightly wired wrong?

s2erst

ive had 12 rs turbos an this is the only one to ever do it thats why i knew it wasnt right. yes it is an escort with 2.1 zetec lump using megasquirt

Rob_DOHC

iTrader: (4)

Just PM'd you mate, but if its doing it with the old ecu and the new one its a wiring fault.

Its not a big deal tbh unless you sit with the ignition on, the problem is that with no inlet manifold vacuum the fuel pressure reg raises the fuel line pressure to around 4bar, in the past i have had a leak caused due to the higher than normal pressure, but with decent lines and fittings this shouldn't be a problem. The fuel pump will also have a shorter life as its on constantly regardelss of whether its needed or not.

Its also not as safe, if you have a crash and the ignition stays on but the engine stops currently the fuel pump will remain on, if all the fuel lines were ripped off the car during the accident you could potentially pump fuel all over the road etc, which is obviously not safe!

But your car will still work,

Its sounds like the ignition relay has been used to power the fuel pump? rather than using the fuel pump relay.

Rob,

tejy

iTrader: (1)

i have braided fuel lines don't know if that would be able to handle the pressure. its been fine when I've driven my escort in the past but the fuel pump did cut out on me once when I was stuck in traffic on the motorway. I had to bridge a wire on the fuel pump to get it working. Where is the ignition relay and how can I sort it?

Rob_DOHC

iTrader: (4)

I think fuel lines are normally rated for a lot more than 3-4 bar (i seem to remember 8bar?)

What wire did you bridge? the fuel pump relay?

Rob,

tejy

iTrader: (1)

will get a pic up shortly just waiting for the camera to charge up its flat and i can only find a usb wire to charge it from my laptop

martysmartie

iTrader: (1)

Encase you missed this, someone has grounded the relay, opposed to wiring it to the ECU.

It's not particularly a big issue, any excess fuel will just go via the return line, the fuel pump runs constantly when the engine is running anyway, it's better to just prime though really.

It makes no difference what so ever in an accident if the pump runs on ignition or not, the power will still be cut, unless someone has bypassed the inertia switch!

Martin

phil_rs

iTrader: (3)

S2s don't have an inertia switch unless someone has fitted one

martysmartie

iTrader: (1)

The ERST fuel pump relay is a timed relay, this is what causes the prime, these relays fail and people do not replace them with the same and correct relay, instead they bodge and fit a cheaper conventional SPST relay!

Ignition relay is irrelevant.

If yours runs constantly you have the same issue as the OP, i.e. it has a permanent ground, if yours is standard and so MFI, the "Speed sensing" module is what keeps the relay closed when the engine is running, this does not apply to OP as he will have aftermarket management.

Martin

martysmartie

iTrader: (1)

Oh right, I was just using that as an example, in any case if one was removed (Where fitted) this is where the danger lies, it seems Ford were not particularly worried about safety issue's with these or 3DR's lol.

Martin

tejy

iTrader: (1)

ok got some pics - this is just purely to show how I got my fuel pump to work when I was stuck in traffic and my escort cut out - It cut out because my fuel pump wasn't priming when turning the ignition.

*Edit* It was just a quick fix until I got back as I was 100+ miles away from home. I dont know what my mate did to sort it but he fixed it the same day I got home

It still runs constant now





Can you see the wire bridging the 2 across





I'm running mfi and I replaced the fuel pump with a brand new one from speedshack it cost me £40 - I remember because I was shocked at how much it was for a bloody relay!

martysmartie

iTrader: (1)

Like I say due to expense, that is why some people don't bother and bodge them!

I suspect what he has done is fit a cheap SPST relay and permanently ground it, which is the totally wrong thing to do, simply replacing with the correct relay would have sorted the problem.

Martin

tejy

iTrader: (1)

What can I do to sort this?? where do you reckon its grounded from? Just so I know where to look rather than taking my dashboard out again if I don't need to

martysmartie

iTrader: (1)

You just need to look at the relay you pictured, I will bet it's no longer the same as the one you pictured, and also look at the wiring to see if anythings been changed.

Martin

mgtkr1

my relay has just packed up. bridged the relevant wires to confirm it was said relay. seems a common fault on a 20 year old rs turbo. just ordered one, £46!!! still, at least its right. am i right in thinking the relays job is purely to supply the fuel pump with a signal telling it when to pump juice? ie at start up and as and when it need during idle? just because on start up it would prime, then the pump would run constantly until ignition is killed. was never a problem when the relay was working.

martysmartie

iTrader: (1)

No, the RST relay is not a conventional relay, rather it's a timer relay (hence the expense), it contains a time delay mechanism, so to activate the pump so it can prime.

When the engine is running the "Speed Sensing module" keeps the relay closed with ignition pulses and thus the pump runs constantly.

Martin