Power for fuel pump

So I am replacing my digital Dash with Guages I was told that the oil pressure sending unit (GM) has a switch in it that supplies the power to the fuel pump after start up my nes sending unit does not have this of course so how would I go about rewiring power for the ful pump after start up or does it get its power from the ignition or can I just wire it with a switch or is there another way

Yes, it's the main switch for the fuel pump, the relay is wired parallel and supplies while starting. Leave the stock sender in place and put a sender for the gauges elsewhere, like above the filter pad.

could i "T" the connector at the factory sending unit and put both sending units there if now how do I go about putting a sending unit at the filter pad I woulod imagine I would need to drill and tap it any adcvice as ti where to put the hole or any of that not something I have done before

Yes, you can T off it no problem.

There's an allen plug above the filter pad, you can put a sender in there. Many cars have one there. Don't confuse it w/ the hole for the clutch pivot though. No need to drill and tap, ready to go NPT hole right there.

See where the big sender is sticking out above the oil filter? That's the port (this is a camaro oil press switch/pressure sender)

Thanks just got done putting one there I just took out the oil temp sender and replaced it with the oil pressure sender for my guage thanks again

There's the Aeromotive Fuel Pump Speed Controller. It senses engine rpm. The rpm reading comes from the distributor; the HEI tach output signal..I think it's also work with traditional breaker points.

The speed controller applies chopped DC to the fuel pump at low engine rpms so that the pump runs at a slow speed. As the engine speeds up, the speed controller speeds up the fuel pump. At a rpm that is adjustable, the speed controller applies full DC to the pump. On my car I think it's set at 2500 rpm. When I turn off the ignition and the speed controller senses 0 rpm. it shuts off the pump.

The speed controller therefore provides the fuel pump off safety feature, and also by cutting down fuel pump speed at low rpm is lower noise and wear and tear on the pump. The controller is a little expensive, costing something over $200.

On GM EFI cars the ECM monitors fuel pump voltage. If it doesn't see the pump get voltage from the oil pressure switch while cranking it will not pulse the injectors

In event of a wreck, any carb'd car will kill engine by fuel slosh in the carb....fine, and in the camper project here, I wired the booster fuel pump through a oil pressure switch on back of the SBC....also not a problem....

but in a FI car, such as my '72 shark, the thing is wired like a '91 Fbody....surely the fuel pump signal hits the computer, and of course it runs, trick is....WTF ever actually kills the engine in event of a fairly serious wreck??:stirpot::hunter:

mrvette said:

.WTF ever actually kills the engine in event of a fairly serious wreck??

Click to expand...

Nothing;
when engine is running the computer has the pump relay working and engine oil pressure keeps the oil pressure switch closed so you have two sources of power to the pump.
Because it is a "oil pressure " switch many wrongly assume it is a safety switch to save the engine if oil pressure drops

vetteoz said:

mrvette said:

.WTF ever actually kills the engine in event of a fairly serious wreck??

Click to expand...

Nothing;
when engine is running the computer has the pump relay working and engine oil pressure keeps the oil pressure switch closed so you have two sources of power to the pump.
Because it is a "oil pressure " switch many wrongly assume it is a safety switch to save the engine if oil pressure drops

Click to expand...

That is what I have to ASSume from the wiring diagrams I have seen too....now a later airbag car I suppose/ASSume has that all in the computer....

obviously is engine/fuel supply is cut, and fuel pump quits in a second...same time out as the start sequence, I believe...