Ignition mode and fuel pump relay

[westy64]

I am a newbie in relays, so I do not understand how this one is wired.
I still don't even know what an ignition mode relay is.

Pink (powered when ignition on RUN) on 30, bridged to 85
Oil pressure sending unit on 86
Fuel pump power on 87

My questions :

why wiring 30 and 85 together ?
how can the oil pressure sending unit send a signal to close the relay ?
or is it the reverse ?
is it a way of wiring it "normally closed" ?

thank you for your help on this

[manoa matt]

The ignition mode relay was installed on cars that used a dual points distributor. When the car is started one set of breaker points are used, once warm the second set of breaker points is used. The ignition mode relay switches the power from one set of points to the other. The switching of points is an emissions thing. You can simplify the circuit here: http://www.international-auto.com/fiat- ... ersion.cfm

The fuel pump is grounded via the oil pressure switch near the oil filter. Theory here is that in the event of a crash the car will loose oil pressure and shut off the electric fuel pump reducing the risk of a fire.

[westy64]

Thank you Matt,

and thank you IAP for their article.

everything is clear on this area now.

[Fi8spider]

The fuel pump is grounded via the oil pressure switch near the oil filter. Theory here is that in the event of a crash the car will loose oil pressure and shut off the electric fuel pump reducing the risk of a fire.

...and very often overlooked when converting from a manual pump to electric.

We had an electric fuel pump installed in our track car (Fiat 131) by the previous owner that operated when the ingnition was turned to reds (ignition mode). It was one of the first items we had our auto electrician tend to and rectified, he used a 7 pin Ford relay which is also used in BMW's and a whole stack of other models, If you get stuck I can rummage around and find a part number for you. Racing regulations over here state that the electric fuel pump can only operate whilst the engine is running.

From a safety perspective, it's a no brainer.

[westy64]

...and very often overlooked when converting from a manual pump to electric.

We had an electric fuel pump installed in our track car (Fiat 131) by the previous owner that operated when the ingnition was turned to reds (ignition mode). It was one of the first items we had our auto electrician tend to and rectified, he used a 7 pin Ford relay which is also used in BMW's and a whole stack of other models, If you get stuck I can rummage around and find a part number for you. Racing regulations over here state that the electric fuel pump can only operate whilst the engine is running.

From a safety perspective, it's a no brainer.

On my second step reflexion, I am confused again.
I understand the safety issue.
But how does a safe system operate ?

Cranking the starter => engine turns=> oil pressure increases => fuel pump powered => carb is filled => engine starts ?
Does it delay a lot the engine start when carb tank is empty (after a storage or carb service ?) ?

Prunette was not wired this way, as the pumps started with key on RUN, although it was not a converted from manual to electric, being a 76.
Prunette has definitely a strange wire harness, as these wires are in place, but do not operate (see above).
I wonder if there is not a separate power for the pump.
Got to check this evening.