Hi,

I have a 2001 C5, and replaced the right side fuel pump assembly, which worked OK for about 6-8 months. Then it would only read 7/8 full on fill up, then sometimes, after 100 miles after fill up, it would drop to 0, requiring I reset the code.

I tried several bottles of Techron, with no difference, so I took it to the dealership, who used a detailed scanner/computer, and said the right side fuel pump assembly was defective, and quoted me $1000 to replace it. I bought the assembly off Amazon for a little over $200, and had it replaced in a little over an hour, taking my time. I had run the fuel below 1/2 tank, so I didn't have to drain anything, since the right side empties before the left side.

Any suggestions on how to fix it permanently, or is this going to be an ongoing issue?

 

There is a sending unit in the left tank as well. I removed both sides on my 2001 and cleaned the sending unit boards with lacquer thinner and a soft brush.

I had tried the Tectron treatments for over a year, but it never did fix my problem.

I also had a reflash done on the PCM concerning the fuel guage on the c5.

After both of these things being done I have had no more problems with the fuel guage going to zero.

If I were you I first would pull the codes from your car then post them up here and others will help you with your problem.

The reason I went ahead and pulled and cleaned the units was the ease of the job and then would know that they were clean and not the problem.

The re-flash of the PCM was also another step that I went ahead and did for added security. It cost me $25.00 at the dealership.

GM Service Bulletin TSB 02-06-04-010A

Good luck with your repair.

 

Thanks for the reply. I already had the most recent PCM reflash done a couple of years ago. After I switched out the right side fuel pump assembly, I cleaned up the contacts with some fine grit sandpaper after checking the resistance moving the float, and finding that the resistance was not smoothly changing along the float sweep. Maybe the laquer thinner was a better way to clean the contacts.

I have owned GM vehicles over the years, and the C5 is the first I have had with fuel gauge issues. It doesn't happen after every fill up, so for now, I am resetting the PCM code to get the gauge working again.

I had the tuner who did a tune for me disable the code that caused the gauge to fall to empty, but he forgot to include it when he reflashed the latest PCM code, so about 6 months later, it started again. The tune the guy put in had a few things I liked on top of the fuel map and timing alterations. It eliminated the 1st to 4th lockout and also cut the electric fans on at a lower temperature. The car stays much cooler now, hardly ever over 200 degrees. Only cost $150.

 

Solvent and soft brush is fine, or a soft pencil eraser, but not sandpaper. This kind of contacts are usually gold plated, like they do to the edge contacts in computer expansion cards, and you do not want to remove the thin layer of gold. If you do, it's basically the end: problems will soon develop again.

 

That is good to know. I touched up the contacts on the old one just to check.