Fuel pump test

[Ross1]

I am trying to figure out a no start issue with my 2001 Boxster S.  It began with intermittently not starting when it was warm. I suspected a fuel issue, so I replaced the filter.  Immediately afterwards, it would start and run fine one day, but not the next.  Finally, quit starting at all.  I disconnected the tank line at the filter and jumped the relay to check fuel volume.  No fuel came out.  So I suspected the pump was bad.  I removed the pump and applied power.  The motor ran.  I then placed it in a bucket of water, applied power, but nothing came out of the fuel lines.  I ordered a new pump.  Got it today, and tried the same test.  Nothing comes out of the lines.  I must not understand how this thing should operate.  Can anyone give me a “clue”?

[crwarren11]

I am far from an expert but I had a fuel pump go out and the tell tale sign for me was the pressure at the fuel rails. Easy to check at the schraeder valve on the rails. I had also gone through the process at the crankcase sensor but that turned out to be fine. 
 

You might also check out this thread. 
 

 

 

[Ross1]

I’m trying to figure out a good way to test the fuel pump while it is out of the car.  Logically, I would think that the pump would   push fluids out one of the hoses when voltage is applied to the pump.  My assumptions is that the new pump is good. I don’t understand why it would not send fluids out the hose when it is outside the vehicle and being powered while submerged in fluids. Any insight would be appreciated.

[JFP in PA]

It would not be the first new fuel pump that was a dud right out of the box, particularly if it is an aftermarket pump.

[Ross1]

I’m trying to figure out a good way to test the fuel pump while it is out of the car.  Logically, I would think that the pump would   push fluids out one of the hoses when voltage is applied to the pump.  My assumptions is that the new pump is good. I don’t understand why it would not send fluids out the hose when it is outside the vehicle and being powered while submerged in fluids. Any insight would be appreciated.

9 hours ago, JFP in PA said:

It would not be the first new fuel pump that was a dud right out of the box, particularly if it is an aftermarket pump.

The pump actually runs.  It is an OEM replacement and looks exactly like the original.  Include number designations.

 

I was experimenting with the old pump, and noticed fluid was pushing out the bottom.  I reversed polarity (positive on black, negative on red).  The pump started working properly.  I went back to the car and did a continuity test.  The red wire on the pump traces back to the solid red wire on the harness that connects to the sending unit.  That wire is connected to ground.  So, it seems the pump wire colors are not accurate in regard to convention.  The new pump is colored the same way.

 

I’m confident that I needed a new pump.  I tried to do a volume test on the old pump, but the motor began to fade after about 10 seconds.  Time to put the new pump in.  Thanks for the good karma on figuring it out!