After spending many hours wrestling with a fuel pump issue, and wasting a lot of time on relay #75 on the relay board. and ultimately discovering that relay doesn't run the fuel pump on an L-jet car, I have to ask... why the heck is it even there if it isn't used?

I think I know the answer, but since i'm a Djet guy I can't answer. sorry.

I think once they designed the relay board for the 1970 D-Jet cars, they never changed it. L-Jet doesn't use the fuel pump relay on the relay board.

Go here to learn how the double relay works.

Typically auto maunfacturers have a bunch of parts in stock as completed sub-assemblies. The relay board, complete with the relays, fuses and voltage regulator was probably like this. So when they put the L-jet injection on, they didn't bother to remove the unneeded relays.

Thanks for the samba link that is interesting.

It seems that the gm idea of using the dual oil pressure sender to hold the fuel pump energized while the oil pressure is up is a simpler way to do it to me.

Great link for the dual relay, thanks for sharing. Is there a similiar explanation for the relay(s) under the passenger seat ??

Seatbelt relays,

It's another poorly thought out part of the all encompassing desire of the Government to help you whether you want it or not.

For those of you that fail to buckle your seatbelt, the under the seat relay is designed to make you to follow the law by preventing the car from starting.

Move the car from the drive into the garage? Buckle up or no starty.

Try to see if the engine will start after you worked on it all day? Buckle up or no starty.

To make it especially insidious, there are pressure sensors in the seat. They are also hooked to the relay.

The pressure sensors are another of the the Government's way of protecting you.

No ass in the seat, no starty.

If you are trying to start your car after working on it, both the belt must be buckled, AND your ass must be in the seat. Fail to do both of those, and you can waste a lot of time and money fixing things that aren't broke.

Did I mention hit a bump while driving????, That's real fun. The bump can cause the seatbelt relay to drop, and that kills your engine.

So if you are accelerating while trying to merge in front of an 18 wheeler that's doing 75 and you hit a bump, the Governments infinite wisdom will allow your relay to drop and your car to die right in front of the oncoming speeding truck.

But no worries, your buckled seatbelt will keep you safe as you get run over by ALL of the the 18 wheels.

Or, simply break the law by pulling the seatbelt relays and jumpering the yellow wires.