Testing for faulty fuel pump

[JeremyH]

No not resistance, you could check amperage/current pull of each pump to see if the is a difference. But sometimes the motor can be fine and pulling amps put not moving the right amount of fuel. When I had a pump go bad it still ran fine but wasnt moving fuel.

 

[Beerhunter]

Oh man, back to the drawing board. Replaced the pump and still no go juice. Going to have to go back to the beginning. Although it should be a bit easier to troubleshoot knowing it is not the fuel pump and knowing that the problem is caused by somehting that prevents the fuel pump from starting. I still don't hear a "whirrr" when I turn on the key

 

[JeremyH]

So does the car start and is it driveable?

Replaced the fuel filter yet?

My next check would be the inertia swith, could be faulty/intermittent as well as the relay.

 

[Beerhunter]

So does the car start and is it driveable?

Replaced the fuel filter yet?

My next check would be the inertia swith, could be faulty/intermittent as well as the relay.

It will not start. Pump doesn't come on at all. I have swapped the relays around and no go. Checked the inertia switch all is good.

I get voltage to the pump when the key is on but the pump doesn't come on. Whatever it is prevents the pump from coming on. I'm going to double check the relays. It has to be something like that.

 

[JeremyH]

Replace the fuel filter too.

Are you sure its fuel related at this point?

 

[Beerhunter]

Replace the fuel filter too.

No, only the one attached to the pump. Would this prevent the pump from starting up?

 

[JeremyH]

No, only the one attached to the pump. Would this prevent the pump from starting up?

It would keep fuel from he rail. The pump doesnt always make noise if there is pressure already in the line/rail. At key on if there is nothing to prime its rather quiet. The swish or woosh sound is normaly happens after the car has sit for awhile and pressure in the line and rail has bled off.


Remove the hat from the tank with the wire plug stil connected, then turn the key on and listen or feel to see if the pump is on.

Also when you disconnect the fuel line from the hat if there is alot of pressure and fuel spilling from the line then the pump was working.

 

[thump_rrr]

Let's stat at the beginning.
Do you have a tuner?
If you do can you datalog?
If you can datalog do you see if the FRPS (Fuel Rail Pressure Sensor) shows pressure?
Your FRPS should show 39psi with the engine turned off.
If the FRPS is showing 39psi then the pump would not try to turn on the pump since the system is already primed.
If it is showing pressure you can uncouple the fuel line with a disconnect tool and a rag over the line (with the key off) to release the pressure.
You could then put the line in a jug to see if it will pump fuel or reconnect it to see if it will reprime the system.