matthew yergeau

Long story short, gave the car to my nephew, rusted fuel lines replaced and wouldn’t run due to no voltage at pump. External 12v pump runs car starts. No continuity green wire with yellow stripe from fuse box to pump. Replaced (rigged horribly) with battery power direct to pump. Will not run unless higher rpm’s, obviously flooding engine,
after all that what I need to know, what exactly that fuel pump relay does. It isn’t a regulator etc does it kill the circuit depending on demand ?
yes I know it’s butchered, the kids 19 years old and I just wanted him to drive it in the snow.

Sleeper8

The relay keeps the fuel pump running as long as the engine is turning. If the engine is on, the fuel pump should be running. There is no variable speed or anything like that, the fuel pump is either full on or full off.

I don't recall exactly where the signal for the relay is generated, but I believe it is in the ignition system, and again, the fuel pump should be constantly full on if the engine is turning.

The fuel pressure must be constant for the system to have any hope of working properly and is regulated by the fuel pressure regulator which resides at the front of the fuel metering assembly.

The relay has nothing to do with fuel pressure, it only controls on or off of the fuel pump.

Rogviler

Yeah, the relay gets a signal basically through the hall sender in the distributor (which can definitely go bad), so anything weird in the ignition system can affect the fuel pump. It's also pretty common for the relay to get cracks in the solder joints. I've successfully resoldered them. If you get a new relay it'll most likely be for a 4-cylinder, so it won't have the correct rev limit (too early), which is one thing the relay does control. But I've been driving around with one of those for awhile since I can't find the correct one and it's not too bad unless you like to race this painfully underpowered car.