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Hey everyone! New to the group, just got a 2000 blazer 4.3 4x4. Previous owner couldn’t diagnose the trans not shifting outta second so I got it cheap cheap ! Fixed that right away by repairing a broken wire for the speed sensor. Anyway not to beat a dead horse but I’m a little confused with a fuel gauge problem I’m having…. Gauge has always read below E but today while the vehicle was running I cleared a code (dirty MAF) and as soon as my scanner cleared it the fuel gauge jumped instantly to full and came right back down to where it was below E. Thought maybe my eyes were fooling me but as I tried again the same situation appeared. Little back story to this before I bought it a shade tree mechanic installed a used engine and also the used trans shortly there after, so I am chasing down a good amount of gremlins that I have came across from the lack of professionalism while all this was done prior to me. I am a diesel mechanic and very mechanically inclined but I am at a loss at this point. Any help is greatly appreciated!!!!!
Its a classic resistive level sensor in the tank with a single wire to the VCM so that can be checked. After the VCM gets the fuel level from the sender it combines it with most other gauge function values, send a serial data stream on the class 2 bus to the IPC for decoding and display. That part is not a DIY thing other than maybe swapping VCM's. Of course the fuel gauge itself can be bad or it could have an internal IPC fault like cold solder joints. I have no idea about the scanner and the possessed fuel gauge, never seen that one before.
There's actually a TSB for the fuel gauge being inaccurate.
Originally Posted by GeorgeLG
Its a classic resistive level sensor in the tank with a single wire to the VCM so that can be checked. After the VCM gets the fuel level from the sender it combines it with most other gauge function values, send a serial data stream on the class 2 bus to the IPC for decoding and display. That part is not a DIY thing other than maybe swapping VCM's. Of course the fuel gauge itself can be bad or it could have an internal IPC fault like cold solder joints. I have no idea about the scanner and the possessed fuel gauge, never seen that one before.
Not sure why I've never noticed before, but my dad and I own and operate our own dealership and service business. Last fall I had damn near rebuilt a 2003 2 door 4x4 blazer and roughly a months after that I acquired a 2003 Blazer extreme and noticed it the gas gauges on both were sporadic at times. The 4x4 truck had just received a gm fuel pump as original was failing so it wasn't an Internet cheapie. But my Xtreme also has the same intermittent issue. It'll drop to E and trip the low fuel. Then sporadically jump back to where I know it's somewhat accurate. What's wierd is on my Xtreme I can hit the locks inside or turn key to accessory and I can watch the fuel gauge trip out. Very odd. Idk what the deal is but it seems to be common for the later years of GM has put out a TSB.
I have a 2001 Blazer. My gas gauge was doing the same thing. I first replaced the fuel pump. That didn't do any good. Come to find out the gas gauge itself needed to be calibrated because the guy that's going to do it said that there is some sort of liquid behind the needle that's gone dry. The installation of the pump was was 750 bucks and to get the gas gauge calibrated is going to be 335 bucks. I needed to change the fuel pump any way but for those folks that are having issues with the gauge itself then I would just spend the money to get it calibrated. If you can pull out the gauge panel that would also be cheaper.
08-29-2022 | 03:45 PM
Fuel gauge concern
