My fuel pump will come on for about 3 seconds & shuts off. Not enough time to build up pressure.
I just installed new fuel Pump, Sending Unit, Filter & Fuel Pump Switch, nothing helps, Turn on switch, fuel pump will run about 3 seconds & shuts down.
What am I missing here, Please Help.

 

Three seconds is tons of time to build up pressure.

Is the regulator leaking?

 

I haven"t found any leaks anywhere, I thought maybe the fuel switch was bad so I replaced that also but it just won"t build up any pressure, the fuel pump keeps kicking off before the pressure builds up in the fuel rail, I have no pressure at the fuel pressure regulator, when I push the fuel relief valve I get fuel but there is no pressure behind it, it just trinkles out.

 

Sounds like maybe a computer issue. Here's my theory - might not be a good one, but it's something to look into...

The ECM is preprogrammed to run the pump as soon as key is turned ON for a few seconds to prime the system - sounds like your getting that function.

But then, the ECM runs the pump after startup by means of "sensing" a constant ignition signal - no ignition signal to the ECM and the ECM won't feed the 12v+ to the relay to run the pump. Sounds like maybe that part of the ECM is malfunctioning.

I'm certainly no expert at this - but maybe you can find out what sends this ignition signal to the ECM - maybe that's the problem - maybe ECM is just not getting the signal. Not sure if this signal comes from the distributor, or the ESC module, or what - but maybe you just have a bad wire to the ECM, and thus it's not getting that 'signal' from the ignition.

BUT - the Oil Pressure Sending Unit should run the pump in the event that the ECM pump function fails. Have you tried just letting it continuously crank for up to a full minute to see if the OPSU would kick in, run the pump, and start the car? The OPSU is supposed to run the pump when it senses oil pressure (if the ECM/relay circuit isn't functioning).

Check the fuse that was supposed to be by the battery in a 3rd gen car (I see this is not a 3rd gen). It was a 20 amp fuse, all by itself in a weatherpack near the battery in the 3rd gen, has one red wire in, and one orange wire out. That fuse supplies battery power to the ECM as well as supplying the OPSU with battery power to run the pump if the ECM doesn't.

 

Replace the regulator.

 

^X2

 

How much gas in the tank? when you put a new pump in most of the lines become empty and that means air in them also. make sure you have atleast 5 gallons in it, then prime it more than once. you can also start it while you prime and if done correctly your fuel psi will come right up.