i have a 1986 305 5.0 v8 tpi fuel injected automatic trans am

ive replaced the injectors, distributor cap, rotor, ignition module, wires and plugs

fresh battery

new fuel filter

it has the original fuel pump relay


my question relates to why my car takes a good 3-4 seconds to finally fire up.

like 1.....2.....3.....etc...

i know if the fuel pump relay is bad the oil pressure switch allows you to drive the car

btu what is the real task of teh fuel pump relay like when does it function and wat does it do?

and could the starter be going or just dirty connection?


any ideas?

 

The ECU uses the fuel pump relay to control the fuel pump.
Normally, it runs the fuel pump for 2 seconds when you turn the ignition on. That's the prime cycle. Then once the engine starts turning (pulses start coming from the distributor), the ECM turns the fuel pump on again.

So if you turn the ignition on and you don't hear the standard 2-second "whine", you might possibly have a problem in the relay circuit.

Hope this helps.
Lou

 

but if the car runs and drives is it possible for the fuel pump relay to be bad and just relying on oil pressure to drive?

 

Definitely.