Fuel Gauge Issue with New pump
 

Working on a 99 Ram 1500 4x4 5.9L My fuel gauge was working fine from F to E. I installed a new fuel pump, a spectra premium that I got from autozone. After installation I noticed the gauge jumped to 3/4 when it was 1/8 or less actually in the tank. Thought maybe just filling it up would reset things, gauge read F for 100 miles until it finally started to move and truck ran out of gas with gauge saying there was almost exactly 1/2 tank left. SO I thought maybe the sending unit was bad on the new one. Brought it in and they warranty swapped it for another. I put that in the truck and the gauge still incorrectly reads the exact same as with the other pump. So obviously not a defective sending unit but perhaps an incorrect one? The installation on this pump is very straightforward so I don't think that is the issue. There is literally one electrical connector just unplug old plug in new. Line up arrow on pump with arrow on tank for orientation. Float arm snaps into pivot hole only one way and holding clamp snaps over that. I didn't notice any kind of calibration and the instructions never mentioned anything either.

This is what I figure could be wrong, since everything was reading fine before I switched pumps I would think the wiring should be ok, so perhaps autozone is wrong on the books about the fuel pump fitting my 26 gallon tank. On their site they report this particular pump works on a 26 or 34 gallon tank but maybe they are in fact two separate pumps and they just keep giving me the 34 gal pump not knowing any better? Or perhaps since I have not owned this truck from the beginning the previous owner may have modified the components somewhere along the lines and a regular pump ohm output doesn't match up anymore. I am going to try to contact the spectra guys and see if there is in fact two different pumps or if there is some calibration that needs to be done that I am not seeing. Also going to see if autozone can look into it more but they believe the pump must be able to differentiate what tank it is in because they only have one part number and no option for a 26 or 34 gal pump.

Appreciate your thoughts and input. :)

AutoZone website lists two Spectra fuel pumps for your 99 Ram
B7138M - for 26 or 34 gallon tank
B7111M - for 35 gallon tank only
Which pump did they sell you and what tank do you have ?

Buy a better quality pump.

They sold me the B7138M- for 26 or 34 and my truck has a 26 gallon tank.

What brand would you suggest? I don't have any allegiance with any fuel pump brand but I wouldn't think a company would just put a 3 year warranty on something just so I can keep swapping new ones until one works.

Delphi, or Denso. They are OEM manufacturers.

Delphi and Denso may be OEM manufactures, but what we are getting for our 20 year old (+/-) trucks
is coming from their aftermarket divisions.
Besides, they are nearly all being manufactured in China, so quality is a crap shoot, no mater what brand that you purchase.

Just my .02 cents

True, however, I have seen a LOT more failures with the likes of spectre, and air tex, than I have with the others.

Alright so I got some time to work on the truck today. I tested the old fuel pump ohm range which falls between standard of about 14-220 Ohms from F to E. Then I tested the 2nd new pump I got which also fits the range just as well as the stock original. Any idea what caused the fuel gauge to suddenly start reading wrong when I disconnected the old one and connected the new one. Both have the same resistances but now the gauge just won't read correctly. Do I have to wipe the computer somehow? Do I need to have the battery connected when I hook it up? Does the tank have to be empty?? I am at a loss.

You could try resetting the computer, as I am pretty sure even the friggin gas gauge goes thru it......

Have you tried a gauge test yet? Just hold the trip odometer reset button in, turn on the key, let go of the button, and everything on the cluster should 'test'. All the lights come on, all the gauges sweep, etc. Make sure the gas gauge does what it is supposed to.

Well took the tank down again for the 3rd time and hooked the old pump up to the connector dangling in the air. It read F to E just fine. Tried the new pump it also read F to E. Put new pump back in tank which was about half full eyeballing it. I slid it under the truck and hooked the connector up and the dang thing read 3/4. So slide it back out and emptied the tank then slide it back under there and it read empty. So that's better than when the tank was empty and the gauge would read half. So I strapped the tank back in the truck. Checked gauge, still reading empty, put 2 gallons in to start and it read 1/8 with 2 gallons and I'm thinking son of bi*** 26/8 is 3.25 so already reading a bit off. Drive down to the gas station and put 4.5 gallons in to make 6.5 or 1/4 of 26 gal and the thing just reads under 1/2 but more than 3/8. So the darn thing is still off but better than what it was. I'll try resetting the computer at some point. But I'm pretty fed up with it and might just bring it in to a shop to get the gauge reading correctly and make it their problem to deal with. As much as I hate to say that.

Been a long time so to sum up quick. Put a new fuel pump in this truck about a year ago and when the tank was empty the gauge would read it was half full. Returned that pump under warranty and the new pump had the same issue but instead of half a tank it was 3/8 of a tank off. 1999 1500 5.9L Pump has arrows to line up with [ ] lines on tank it self.

I recently rebuilt my transfer case in this old beast. While I had the drive shaft out I figured I would pull the pump down again and do some DIA on this fuel pump to gauge misreading issue. This time I just decided to bend the float arm to read correctly. I emptied tank (maybe had a gallon left in it after emptying) and put in two gallons. Pump was reading below red line empty. So I added one more gallon to see if it would move from there. It did move to just under an 1/8 of a tank fuel light still on. SO figured that's close enough for me versus the old 3/8 of a tank off reading when the tank was actually empty. All said and done I start driving to town(15 mile trip) tested out 4x4(working great now) and about 5 miles down the flat road with just the 3 gallons of fuel she starts sputtering and rpms dropping out and just dies on me. Dad brought me 5 gallons, added that and the just below 1/8 gauge jumped to 1/2 tank. Its a 26 gal tank and at this point it would have 8 gallons. Started back up just fine finished driving to town. Had to go up a very steep hill so I started at the bottom at 80 Mph because I figured fuel would pool at back of tank and she would cut out on hill. Sure enough it started to sputter out just at the top of the hill but had enough speed to make it up. Never died. Got to town and put in 21.020 gallons of fuel.

So my question is, why did it die out with 3 gallons of fuel? Is there something I am missing here? Are these pumps not able to suck off the very bottom of the tank and need to have a few gallons in at all times even on E? I think at this point my Spectra pump is just no good. Another issue its having now, is after idling for about 3 minutes everything good the idle will start to sound weird and it will eventually just die like it ran out of fuel. Never had this issue before. Can air get trapped in the fuel line causing this? Or again do I just have a garbage fuel pump.

Thanks for the feedback you guys are great!

Oh I should mention about two years ago I rebuilt the engine on this truck with new Edelbrock heads and the FI air gap from Hughes engine new pick up coil on distributor and stuff like that. Truck has always ran top notch since rebuild and I did have a shop check it over as it was my first rebuild completely self taught. I was a little nervous it was just going to explode at any moment and wanted some outside assurance.

I believe you just have a garbage fuel pump. I am having the sense problem though. Swapped an OEM fuel pump that worked and the sending unit doesn't read at all. I plan on buying Delphi as they were the supplier to Dodge. I know personally my old pump had an issue where (no matter how full it was) the harder you ordered the gas the quicker the gauge went to E. Let off and it would go back to the correct reading. My old pump also would suck all but about a half of gallon out of the tank.

Yeah, what brand pump are you putting in there? Air-Tex??

Who me or the OP? OP said Spectra

I don't think they are any better than Air-Tex..... Denso, or Delphi please. :D

Mine was OEM lol. Every brand has their problems but when I buy a new one I will buy Delphi