Fuel gauge issues after lift pump install

[Matdman]

Hey all, just put a PD lift pump in my ALH Jetta. Works great, it's just now I'm having fuel quantity issues.

When I first installed it, it was reading 1/4 tank low and was not moving. Last week I swapped the float arm and potentiometer from my old fuel sender unit onto the new pump, same issue. And yesterday I oriented the float arm as it was when I pulled the original sender out.

It is now reading the mark above 1/2, and it is not moving. I filled it up today and it hasn't budged. Does anyone have any ideas on how I can get the level sender working again?

 

[LNXGUY]

You sure you got the wiring correct? The arm is definitely moving, but you're not getting the proper signal.

 

[Matdman]

You sure you got the wiring correct? The arm is definitely moving, but you're not getting the proper signal.

Wiring is definitely correct. If the pump is out of the tank and I move the float, the gauge moves. So I'm assuming the float is stuck somehow.

 

[LNXGUY]

Did you orient the pump properly when in the tank? It almost sounds like the float is filling with diesel and not floating.

 

[Matdman]

Did you orient the pump properly when in the tank? It almost sounds like the float is filling with diesel and not floating.

It's oriented the same as the original sender.

 

[Matdman]

Anyone else had this issue? Fuel gauge hasn't moved in 3 days since filling up.

 

[LNXGUY]

Did you vent the tank? (ie fill it up to the brim?) If so, my needle doesn't move until I've put almost 300-350kms on it.

 

[Matdman]

Nope, only till the pump stopped. And what I mean by the gauge hasn't moved is that it's been stuck at 5/8 full even right after I filled up. It hasn't budged.

 

[LNXGUY]

This is definitely a weird issue.

 

[trailhead]

Sorry op for this thread jack...

my needle doesn't move until I've put almost 300-350kms on it.

Really? How many kms until you refuel? Just wondering because mine only goes 230-240kms until the gauge moves (Vented and filled to the brim and running Stanadyne Blue). Last week it run out and stalled at 853kms on the full tank. The previous time (last spring) it ran out at 913kms. I'm wondering if I'm getting bad mileage?

Thnx much,
TC

 

[LNXGUY]

Sorry op for this thread jack...



Really? How many kms until you refuel? Just wondering because mine only goes 230-240kms until the gauge moves (Vented and filled to the brim and running Stanadyne Blue). Last week it run out and stalled at 853kms on the full tank. The previous time (last spring) it ran out at 913kms. I'm wondering if I'm getting bad mileage?

Thnx much,
TC

I've gotten 1200kms if I drive decently before I get the low fuel warning (With exactly 58L to full)

Are you city driving your car? If so, that might be the reason for the low mileage.

 

[JB05]

Is the arrow on the lift pump facing the rear of the vehicle?

 

[Matdman]

Is the arrow on the lift pump facing the rear of the vehicle?

It sure is

 

[Matdman]

So I played around with the pump again, and got it into a position where the float was moving. So I went and filled up the tank, and the float must have filled with fuel because now the gauge is stuck at the very bottom. How do I make the float float again?

 

[LNXGUY]

Find the hole and plug it, or put the float that came with the replacement pump back on.

 

[Randol_8o8]

I would also suggest changing the float to your original one. As they say. If it ain't broke don't fix it!

Ah didn't realize you already did that. You must have a hole in the float or else it would float. are you able to return the pump for a new one? once you've done all the wiring to add the pump changing it isn't that much of a hassle if you're low on fuel.

 

[Matdman]

I would also suggest changing the float to your original one. As they say. If it ain't broke don't fix it!

Ah didn't realize you already did that. You must have a hole in the float or else it would float. are you able to return the pump for a new one? once you've done all the wiring to add the pump changing it isn't that much of a hassle if you're low on fuel.

The pump was pulled from a junkyard car. I'll try the float that came with the pump again when the fuel level gets lower. It's weird that my original float would have a hole in it when before I put the pump in the original fuel sender worked fine.

 

[LNXGUY]

Make sure the other float doesn't leak.. Put it in a tub of water or something.

 

[Matdman]

Put the other float in, and now the gauge works!...for now. Thanks to everyone with their suggestions.