ianshad6

can anyone tell me how a normal relay works???
say for fuel pump or injection relay just wondering how it works id imagine it simple?
thanks all

Craigb

Baically in a relay there is a coil of wire with iron bar inside. Once you pass a current around the coil of wire a electro magnetic field is created and the iron bar is pulled into the coil. Once the current is cut off the electro magnetic field stops and a spring pushes the iron bar back out.

On the end of the iron bar is a set of switch contact, as the iron bar is pulled in and out of the coil of wire the contacts open and close.

SafeChav

They all vary quite significantly.

But as said above, a relay in its simplest from is used to switch large currents/voltages where the supply is minimal.

In simple terms its an electronic switch.

Whats the problem you are having?

ianshad6

basicly im doing an efi convertion and wanted to know how a relay was to work and the pin outs of on ie fuel pump relay as somone has help me out loads thanks
iv been told your the man to ask when doing the efi convertions right?
is there any add vice to give me as im using the ofac loom set up but icant reconiz the map sensor and what it looks like???can you help or give me some addvise pls?

also dose the map senso have to be changed if its been chiped and a set of injector have been replced?ie 701s with 195 chip
and what is the fuel pressure on there efi turbos?

cheaRS

SafeChav

The fuel pump relay on EFI is just a bog standard SPST relay. The injection one is a little different, im not overly sure whats different about it i think possibly it has a switch on delay or internal schotky diode.

You won't be able to upgrade MAP sensor on OFAC, but a standard one is still a ford item but had one corner cut off at a funny angle, other than that its identical to a 3i one.

Pretty sure the fuel pressure is the same for the turbos and N/A engines

Wardy257

Below are diagrams/wiring of 3 different relays used for fuel pumps. The top 2 are used by Ford. The MFI cars had 5 pin tachometric relays, EFI cars have a standard 4 pin relay.

ianshad6

so i also need a relay for the injectors where do that go as i have to already?alittle confused know on what i have to do mabe i bitten off more then i can chew???
but im still confident?

SafeChav

Its easy mate don't worry about it too much.

Ive got a diagram somewhere just can't find it. You could try PM'ing Rab off here as he is the one who made the diagram, it will make your life a lot easier

ianshad6

SafeChav
did you find any diagrams yet as ill prob go and have another go at it this wknd? thanks

SafeChav

Nah i dont think i saved it

Ill see if i can find it here on PF, its around