What would cause the fuel pump motor to run fine but it not push any fuel?

 

My first guess is a clog! Check your fuel filter.

 

I've eliminated that. Disconnected the line from the filter and powered pump directly from battery and there's no fuel flow. There's no blockage on the pickup line in the sump tank. It's seems like that actual pump mechanism that the motor drives is not working.

 

I wonder if the hose came off the pump. In either case you will need to go into the tank and look. http://www.gusglikas.com/images/Auto...FilterPump.pdf

 

Hose is connected fine. In the most recent attempt I was trying to pump out of a gas can just to verify pump operation. the motor runs but it picks up no fuel.

This is a brand new pump from SNG Barratt just a couple months old and only used a few times for maybe 10 minutes each. It is a different type than pictured in your link. Here's some pics of mine.

 

Could it be that the pump wires were crossed and the pump is running backwards? If this is not the case you may want to check the wiring to it. I understand several harnesses have been known to burn up. Let us know what you come up with.

 

This is just a guess, but it may need priming, like an oil pump, with the fuel level above the pump so pick-up side is fed by gravity. Pump on my old XJ6 looks the same as yours, and it was at the bottom of the boot compartment, and below tank level.

Apart from that there is something wrong in the pump itself. Does it have an internal blow-off valve ? If so this could be stuck and if it is it won't pump a damned thing.

 

I had the same problem on my bmw after I changed the pump in the tank, although it took a fairly long time to stop pumping. the pump was running but no fuel pressure, it had become disconnected from the pick up tube just repositioned the pump and put a clamp on the hose easy fix for me I could access the pump through the trunk. Hope this might help you.

 

All wiring seems fine. I've eliminated that anyway though as I'm jumping directly off the battery and polarity is correct.


I just tried priming it with no results; plus it's worked fine before without priming. There is a check-valve at the outlet of the pump but it's not stuck at all.


Pump is out of the car and I'm "bench testing" it jumping directly off a battery so no hoses or connections are the problem.

 

You have power, it is wired correctly, the hoses are connected correctly and priming is not an issue. Test the pump pressure on the bench and replace if necessary. Whatever you do please tell us what you find because I am at a loss.

 

I appologize for all the confusion I've caused in regards to this issue. Apparently, checking and double checking the alignment of the impeller was not enough. Upon a third, more thorough, comparison to the old pump, I found that I had the impeller turned 90 degrees off. I'm a jackass.

So now it pumps fine and the car starts and runs. It seems like it's still idling pretty high (2500-3000) then in gear it drops to about 1000. I'm hoping that's just from the missing TPS that I am still waiting for. Does the TPS read zero resistance at WOT or closed? I am jumping it at the plug just to see if there is any change and there seems to be none. But I don't know if jumping it would replicate closed throttle (idle) or WOT.

Also while it was sitting in storage for the last few years somebody tried to steal the cats. They cut them out but then left them there so I am currently running with no exhaust. Would having the exhaust open and the O2 sensors so close to the opening cause problems with fuel mapping?

 

It is good to know what you found and that problem is behind you. Now for the idle problem.

 

The old black Bournes throttle pots are NLA and the new ones are smaller but need the different (newer) throttle quadrant. They are both 3 wire potentiometers about 5K (I Think) and 2 connections have 5K but the center 'wiper' connector increases with one set of connectors and decreases at the other. In the middle it should read 2.5K equally. I don't know how the ECM reads the resistance (I never checked) but I'm sure shorting wires won't convince the ECM to recognize idle.

bob gauff

 

Here is the parts TSB for the throttle pot replacement

bob gauff

 

Thanks that helps alot. Now it's just finding somewhere that has those parts. I've been dealing with SNG Barratt but they don't have these.

 

Fixing the exhaust could definitely help. In between firing pulses, oxygen will get sucked into the open pipe and could be picked up by the o2 sensors if they are close enough to the cut ends.