Fuel Gauge Problem

[ROADWARRIOR]

Today, I was at 1/8 tank, so I put in 20 gallons with the truck running. When I hopped in the truck the gauge was on E and the fuel light was still on. I drove around for about 20 minutes and the gauge moved up and down around the E mark. I shut the truck off and then the gauge started working and hasn't screwed up since. Is this an early warning that I am going to be blessed with the infamous bad fuel sender problem? My truck just went out of warranty about 2 months ago. How much does it cost to have the sender unit replaced if it does go out?



Thanks, Dan

 

[rrausch]

My fuel sender was screwy when I got my '95 2500 used, about a year and a half ago. The gauge would register full after I filled the tank for about 50 miles before it would start diving down into empty and the little light would go on. Did it every time. I learned to go by the trip OD, figuring I needed to fill up at about 550 miles (in town). I finally got tired of this nonsense and went to a dealer. I believe I paid about $60 for a new sending unit. I drove around until I figured I had about 3 gallons in the tank, dropped it on the street one day, and put the sucker in!

I believe the problem with the sending units is this: Fuel tends to rush forward when you stop, and rush backward as you accelerate. Whether this is caused by too little baffling in the stock fuel tank is open to consideration. The fuel rushing forward and backward of course raises and lowers the float on the sending unit and causes the contact strip to wear prematurely. This is my take. May be incorrect, but I examined my old sending unit and tank, and that's what it looked like to me.

I believe Daimler/C. now will recall your sender if it is faulty, and install a new one for you, but your symptoms don't sound like that to me. Sounds like you had a temporary gremlin in your electrical system. Hopefully it's gone by now.

The smoke detector in my Apt. used to go off at odd hours because a moth liked to crawl into it and sleep there, and moths have a powdery substance on their wings which conducts electricity. Go figure!

 

[Bob Cochran]

I really don't have an answer for you but a question. You said you filled the truck while it is running. Wondering why you needed to do that but what ever. The guage stayed the way it was until you shut down and restarted. Could it be the electronics had to reset? Just a thought maybe full of it but anyway glad it is working again

 

[illflem]

Some sender problems are caused by the float getting hung up the self tapping screws used to put the module together. Usually a good bump will free them though. At least one dealer's solution to the problem that I've heard of is to kick the fuel tank.

 

[redram]

Illflem and Joe G. (from another thread)



Many of the fuel level gauge problems are caused by the infamous unreliable float electrical contact part which can sometimes be repaired for pennies.



However, there is another mode of failure that has NOTHING to do with the float rheostat. The fuel module is built to slide up / down so that the fuel pickup stays in the bottom of the tank as it expands with wieght and temperature. Mine fuel module actually has worn grooves into the white metal brackets. When (if) this happens, even with a fully functional float rheostat, the pivot point of the float can change causing very irradic fuel level readings as the fuel module changes the float pivot point relative to the bottom of the fuel tank.



Just FYI for your information banks. I have one exactly like this- it's been in my truck like this for the last 3 1/2 years.

 

[FFSchooley]

I fill up quite often while leaving the truck running and get the same thing. Ever notice when you take the fuel cap off there is a burst of pressure? The tank gets pressurized, so when you leave it running and fill up, and then put the cap back on, the higher level of fuel pressurized differently(I assume) giving a false reading for some reason or another and the sender will not read correctly until you shut her down and re-start it. Not exactly sure why this happens, but I have had mine doing it for 10,000 miles and nothing failed yet.

Brett

 

[Lurch]

Uh, I allways fuel running, gauge comes right up. It is kinda flakey tho, different gallons to fill at the same gauge reading. Can't trust it to be totally accurate.



Lurch