Problems with my fuel gauge

[hockey_19pro]

I just got a 2000 GMC Sierra 1500. Went to get in the truck the other morning and when I started it, the LOW FUEL messege popped up on the messege board but I know I had almost 3/4 of a tank left. I didn't think anything of it and after drving down the street the fuel gauge went back to normal. The next time I started the truck, it read FULL tank! Then I started driving and the same thing happened, it went back down to normal...Any ideas? I just got off the phone with the dealer that sold me the truck and he said sometimes the gauge will go crazy on that model of Sierra, at the extreme ends (full or empty) until you drive it a little. Can this be true?

[Jeremy airjer W]

It shouldn't do what you have described and something is obviously not working as expected. It is very easy the determine if it is the sending unit or the gauge with a variable resistor. Set the variable resistor to the resistance the sending until should be at full and plug it in to the connector and see what the gauge reads. If it reads correct than slowly adjust the resistance (you will have to wait a little bit for the gauge to adjust).

If the gauge never flakes out than the sending unit is the likely source of the problem. I would say that 99 times out of a 100 its the sending unit.

[zamboni]

How fun would THAT be to do to a neighbor/friend???? One night syphon out, a couple nights later put some back in. They'd think they were losing their minds

[Red Cabin]

I have the same truck with 180,000 on it, it did that for the last 100,000. Fuel pump went out yesterday so I towed it in to the shop, when I picked it up today the guage is working like it should!

[hockey_19pro]

The truck still does it from time to time. I've noticed though that since my fuel level has gotten lower (1/4 tank now) I haven't noticed as much of a problem with the gauge. The dealer told me that it may go back to normal after the fuel level gets low enough, then it will be fine after that. I don't know how much truth there is to this (I'm not a mechanic by ANY means). Hopefully it will be alright...

[The_Duckslayer]

Mine works fine till i get to 1/2 tank then it gets all weird. Goes from empty top full and just sways all over. Each time I fuel up I reset the trip odometer and then at about 275 to 300 miles it is time to get gas again. It will go to about 325 actually but I pused it a couple times and had to call for help! ;-( Mine is a 2000 GMC Jimmy. New pump last month did not change anything. Well actually it was a used pump from Viking so that may be the key there. Oh well notta biggie! Take care and N Joy the Hunt././Jimbo

[Hafnutz]

Have had gas gauge problems with my wife's Mercury. Was told by dealers it could be caused by a build up of sulfhor on the sending unit. I thought yeah right. Ford dealer claims that certain brands of gas have a higher sulfhor content than others and it leaves a build-up on the sending unit. They recommend a product called Techron injector cleaner to eliminate the problem. I tried it and it has worked a couple times now. She buys her gas at the big stations that have are red, white and blue and sell donuts. I buy my gas only at major national brand stations that sell what is called top tier gasoline. I have had no problems with my Ford truck. For what it's worth...

[hockey_19pro]

Thanks for all the posts everyone. I just got off the phone with the dealer I bought the truck from, and had to "remind him" again what the problem was. The dealer told me that the best they could do was cover half the cost, then I really started to get angry. When I bought the truck he said the truck was a certified pre-owned vehicle and it went through a 35-point inspection, he also told me there was absolutely NOTHING wrong mechanically with the vehicle. I know it was my fault by simply taking his word, but when I took it for a drive I couldn't tell if anything was wrong (the gauge only reads inaccurately every few times you start it up). So, I told him they were gonna have to do better than cover half the cost of an approximately $200 part with labor! He then said he would try and get me a better price and possibly cover the entire cost. This made me feel a little better, but still told him to call me before ordering the part and immediately after he found out EXACTLY what I'd owe. My question is, do any of you feel I was too hard on the dealer or that I irrational? Thanks everyone...

[Jeremy airjer W]

It's an intermittent problem that they would likely have never caught. As long as you contacted them in a timely manner (within a couple of tanks worth of gas) to tell them there was an issue than I don't see a problem with at least getting them to cover some of the repair.

On the other hand you are buying a used vehicle that apparently came with no warranty and It sounds like an extended warranty was also not part of the deal and you only have a verbal guarantee. Any time you buy used you are potentially buying somebody elses problem that they didn't want to deal with. That risk is worth getting a vehicle at a price that is reasonable to you. If the people selling you the vehicle are reasonable they should work with you as its sounds like they are trying to do.

When we bought the caravan used the sales gave gave us the inspection report and I told him I was going to hold him to it. I pulled the tires off and the rear drums had never been off, evident by the ring of corrosion that would have to be removed from the hub in order to get the drums off. I called the sales guy and told him I would be right down. They had a tech confirm what I found and he proceeded to remove the rear drums where he found a wheel cylinder leaking profusely. There's nothing like seeing a sales guy trying to double talk his way out of that one. They wanted to replace the one wheel cylinder no charge. I counter offered with they give me one, I'll pay for the other, I'll install them, and flush the brake fluid at the same time. They counter offered with they give me both wheel cylinders no charge. Win for me!

Sometimes it works out sometimes it doesn't in the end its not a brand new vehicle with a guarantee that everything is working when you buy it.