Faulty fuel tank sending unit issue.

MonacoMike

Well-Known Member
Sep 15, 2009
14,721
Indiana lakes and Lake Michigan
Boat Info
2000 Cruisers 3870
8.2 Mercs
Engines
85 Sea Ray Monaco 197
260hp Alpha 1
My 05 Chevy Suburban is giving erratic fuel gauge readings. I fill up with key out and at restart the fuel gauge reads slightly below the full mark. It may show this way for several miles or stops if around town and then it will show over full, (just as it did when new) the function is normal after 7/8 tank. I suspect ethanol corrosion. Anyone have a similar issue? MM
 
Mike, not sure about the starbrite brand but i have fixed over 40 Fords (without exaggeration) with your exact same concern with chevron techron fuel system additive. http://www.chevron.com/products/prodserv/additives/tcp.aspx
The problem stems from excessive sulfur build up on the fuel sender resistance card. You may have to add it for a tank or two and then every once in a while after that. Ford finally came out with a service bulletin/recall to replace the sender unit because of customer complaints.
 
Mike, not sure about the starbrite brand but i have fixed over 40 Fords (without exaggeration) with your exact same concern with chevron techron fuel system additive. http://www.chevron.com/products/prodserv/additives/tcp.aspx
The problem stems from excessive sulfur build up on the fuel sender resistance card. You may have to add it for a tank or two and then every once in a while after that. Ford finally came out with a service bulletin/recall to replace the sender unit because of customer complaints.

Thanks for the suggestion. I'll get some in and report back. MM
 
An old thread revived with new information. The gauge situation never changed from the original post, that is until a couple of months ago. I decided to try the 91 octane ethanol free for a while to see how she would run. WOW!!! Like a horsepower boost. Runs so smooth, yet you can hear the power difference from 87 octane E-10. I tried the 93 E-10 but it did not have near the affect.

After about 3-4 tank fulls, the gas gauge works perfect. It did not work properly for 7 years! Go figure. The cost difference is less than the additive I tried. The performance difference is awesome.

MM
 
An old thread revived with new information. The gauge situation never changed from the original post, that is until a couple of months ago. I decided to try the 91 octane ethanol free for a while to see how she would run. WOW!!! Like a horsepower boost. Runs so smooth, yet you can hear the power difference from 87 octane E-10. I tried the 93 E-10 but it did not have near the affect.

After about 3-4 tank fulls, the gas gauge works perfect. It did not work properly for 7 years! Go figure. The cost difference is less than the additive I tried. The performance difference is awesome.

MM

Interesting. 1.) Do you have the 91 and 93 reversed in this post? If not, the 93 non E fuel would make even more of a difference.

I'm not at all surprised of your "horsepower boost" recognition as some of us are more conscious and dialed into our vehicles performance especially after logging many hours/miles on the same vehicle. When you switch to a higher grade fuel, (even for engine calibrations that do not require it) the P.C.M. recognizes it and will let the timing advance further than usual because it doesn't sense knock under certain calculated load situations which it derives from input information from various sensors i.e. maf, tps, cmp, ckp, iss, oss, along with others depending year make and model.

2.) Do you normally run the tank down to, or close to empty before fill up as this will help the sender unit in any fuel tank, truck, car, boat or anything else for that matter last longer because the resistance card will not wear out in certain areas sooner than if the contacts were being used in a wider range. (think about the float bobbing up and down all the time in a small range in a moving tank.)

As far as the suggested additive goes, since the gauge was not working correctly for so long I would have to imagine the resistance card possibly had quite a bit of build up on it but I guess time will tell. I don't think you need to add it every fill up but once in a while should suffice.
 
Interesting. 1.) Do you have the 91 and 93 reversed in this post? If not, the 93 non E fuel would make even more of a difference.

No, I am running 91 E-Free, I was just commenting that trying 93 E-10 made no noticeable difference.

I'm not at all surprised of your "horsepower boost" recognition as some of us are more conscious and dialed into our vehicles performance especially after logging many hours/miles on the same vehicle. When you switch to a higher grade fuel, (even for engine calibrations that do not require it) the P.C.M. recognizes it and will let the timing advance further than usual because it doesn't sense knock under certain calculated load situations which it derives from input information from various sensors i.e. maf, tps, cmp, ckp, iss, oss, along with others depending year make and model.

Makes sense.

2.) Do you normally run the tank down to, or close to empty before fill up as this will help the sender unit in any fuel tank, truck, car, boat or anything else for that matter last longer because the resistance card will not wear out in certain areas sooner than if the contacts were being used in a wider range. (think about the float bobbing up and down all the time in a small range in a moving tank.)

Yes, much to the wife's consternation, I usually run it down to empty.

As far as the suggested additive goes, since the gauge was not working correctly for so long I would have to imagine the resistance card possibly had quite a bit of build up on it but I guess time will tell. I don't think you need to add it every fill up but once in a while should suffice.

The additive did work in a temporary way, to maintain the constant function would have required nearly constant additive use.



Thanks for the input. See above in red.

MM
 
If you can post or pm me a vin I can check to see if there are any GM associated TSB's (they are vin specific) like the one I mentioned earlier for which, when that treatment didn't resolve the customers concern, a new, updated sender unit was installed and maybe there is a similar one available for your truck.
 
If you can post or pm me a vin I can check to see if there are any GM associated TSB's (they are vin specific) like the one I mentioned earlier for which, when that treatment didn't resolve the customers concern, a new, updated sender unit was installed and maybe there is a similar one available for your truck.

Will pm ASAP.

MM
 

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