Fuel Gauge Problem

[8cylRWD]

My 94 Ranger 4x4 super Cab has 140,000 mi on it. In July I had to replace the fuel filler assy, so I went ahead and replaced the fuel pump/sending unit due to age and mileage while we had the bed off. Bought it at NAPA. The fuel gauge was very inconsistant and often inaccurate with the new unit.. Would take 3-5 minutes for needle to show full after fill-up, drive 75 miles on the highway and the needle wouldn't move, start the truck, drive 3 miles shut the truck off, start it back up and have sometimes 1/8 tank more or less than when I shut it off, etc.
I got a replacement (warrenty) unit from NAPA and installed it this weekend. Drove it 49 miles and still has the same 1/4 tank it did when I put the new assembly in Sunday. The units were not damaged (as near as I can tell) during installation, don't believe there is interference between the fill tube and the float as the float is oriented forward.
The fuel gauge worked perfectly with the original unit, and as I said earlier I only changed it because the timing was convenient and I was getting skeptikal of it due to age and milage.
Anybody had a similar experience?? Thanks Bob

 

[jhammel85]

To be honest, I'd have to say it's a defective pump. That sender for the gauge is in the pump assy. Hopefully you still have the receipt because it sounds like a warranty issue!

Welcome to the forums btw!

 

[8cylRWD]

That's what I figured on the first NAPA pump in July, but as I said, the gauge never did act right with that pump or this one. Maybe I do have two bad ones in a row. Anybody else got a thought? thanks

 

[kimcrwbr1]

To check the guage when you have the pump out find the wire to the guage with the key on it will have about 8v pulsing touch it to a good ground if the guage reads full then it is the sender or the ground to the sender. It is possible you just have a weak ground but I believe the pump and sender share the ground if the pump is working the fuel sender should also

 

[nitrofan1]

Also check the wiring for high resistance. I'm not sure who makes NAPA's fuel pumps. Your big dogs are Carter, Bosch, Airtex. It may be the manufacturer but I'd think it's in the wiring.