fuel gauge failing?

[WaltNYC]

1997 Disco I w/ AEL

My fuel gauge is on the fritz. Some really strange behavior.

First, alternator and battery are in good shape. Getting 12.7V out of the alternator. Battery is only a couple of years old. It fires up easily on the first try consistently.

I only had about 20 miles on the tank so I knew it was close to full. The gauge was at the bottom and the warning light was on.

I drove the car a bit and it appeared that when I came to a stop, the gauge would actually rise a bit.

I pulled off the road, put it in park, and the gauge rose almost to the point where I would expect. I added some throttle to examine if RPMs might be a factor, no change.

After pulling back onto the road the gauge again began to fall eventually hitting 1/4 tank. (total mileage was <10mi)

All other gauges are functioning as they should. OBD readings look totally normal.

A) Is this the potentiometer in the fuel pump assembly or is it worth trying to go crazy with a multimeter?

B) There are $60 assemblies on Ebay and $400 assemblies at the parts houses. Is there a difference? (If the quality of the pump motor is the major difference I could always scavenge the pump that is currently working great.)

Any experiences out there?

 

[LRDONE]

Assuming this is for a D1, The level gauge circuit is within the fuel pump assembly. 4 pin plug, two pins are for the level gauge and the other two pins are for the pump. Aside from making sure the plug connector is clean and tight, you could always remove the pump and do a sweep test while measuring resistance to try and notice any dead spots along with confirming the wiring to your gauge has no issues as well. As for fuel pump assemblies I seem to remember there being a cheaper cross reference pump but I can not remember.

 

[kris812]

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For a cheap 50$ assy and for Visual reference for what LRDONE said..

Can have the pump out of truck in 5 mins flat, if you've done it as many times as I have HAHA.. Give yourself 15mins: Philps to remove cover, straight and a hammer to loosen the ring, some 12mm or 14mm wrenches to knock off the fuel lines; and out it comes covered in juicy fuel.

The wiper gets dirty on these, and I've seen the "tube" that goes from the pump in lower section feeding to the top, break/crack MANY of times!! Even on many different vehicles!

To note, I've had that feed "tube" break on my OEM, a 250$ oem replacement (they were cheaper a long time ago), and on the 50$ ones.
Sitting empty/low on fuel in the Heat is the killer to them..

I vote buy 2x cheapos, and Keep the old pump motor under the hood or in tool box and still be 200 ahead!

BUT open your panel up and MAKE SURE you get the right pump assy.. there is AEL and non AEL and the assy is different for them!!

 

[WaltNYC]

Mine is definitely AEL (square canister). I'll grab an extra sealing ring as well.

 

[kris812]

Mine is definitely AEL (square canister). I'll grab an extra sealing ring as well.

Check fuel pressures before and after the swap.. Good peace of mind

 

[WaltNYC]

The failing gauge is no longer a mystery. When replacing parts that I am not entirely certain are required, I am always happy when I find 'the smoking gun'.
I also took the opportunity to touch up some surface rust.