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Erratic Fuel Gauge


gamato's Avatar
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March 21st, 2007, 12:24 AM   #1  
Erratic Fuel Gauge

I have a 1999 2-door 4wd Tahoe. I just had the fuel pump replaced and when I got the truck back, the fuel gauge is now erratic. It moves back and forth like the blinker was on or something, but not back and forth too far , just slightly. It doesnt jump all over the place and its not too noticable during the day. When I am driving at night and the gauges are lit up, it almost looks like its vibrating back and forth extremely fast like a humming bird almost. Now the mechanic even replaced the 1st new fuel pump assembly w/sending unit and the same thing is happening. It even does this with the truck off and the key turned to the on position. It didnt do this before I had the pump replaced and now no one can figure it out. Any help would be greatly appreciated. Thanks...

 
kpanza's Avatar
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March 21st, 2007, 4:20 PM   #2  
RE: Erratic Fuel Gauge

Sounds like a Ground issue?

 
Black 5.3's Avatar
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March 21st, 2007, 4:45 PM   #3  
RE: Erratic Fuel Gauge

are you sure you have the correct pump and sending unit cos a 99 Hoeis different than99 pickup truckyou probably have a new body style sending unit in there that uses different oms/volt??

to make sure just go back to parts store lookup 98 Tahoe part number and check to see if thats the same part you have in ur truck

 
bee46's Avatar
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June 2nd, 2007, 9:32 PM   #4  
RE: Erratic Fuel Gauge

ORIGINAL: gamato

I have a 1999 2-door 4wd Tahoe. I just had the fuel pump replaced and when I got the truck back, the fuel gauge is now erratic. It moves back and forth like the blinker was on or something, but not back and forth too far , just slightly. It doesnt jump all over the place and its not too noticable during the day. When I am driving at night and the gauges are lit up, it almost looks like its vibrating back and forth extremely fast like a humming bird almost. Now the mechanic even replaced the 1st new fuel pump assembly w/sending unit and the same thing is happening. It even does this with the truck off and the key turned to the on position. It didnt do this before I had the pump replaced and now no one can figure it out. Any help would be greatly appreciated. Thanks...
With the exception of mine being a 4-door 2wd, my situation is identical. The factory original pump went out at 105K miles and I installed an aftermarket pump and the symptoms described in this thread started. That pump failed after 6 months and 2K miles and was replaced with an AC/Delco MU149 and it too shows the identical symptoms.
I noticed that in a reply from Black 5.3 that there are two different style sending units for the '99 year model. Have you been able to confirm that this was your issue? btw, the parts books that I have seen also called for a MU149 for the '98 models, but again perhaps the sending unit is different?

 
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June 5th, 2007, 9:57 PM   #5  
RE: Erratic Fuel Gauge

I have a 2000 tahoe and the gas gauge started doing the same thing but after awhile it now goes from empty with the idiot light on to full then half full then quarter tankand all over the place. Its almost like I have a magic refilling gas tank. I have not had the fuel pump replaced so I know it not that.

 
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June 5th, 2007, 11:44 PM   #6  
RE: Erratic Fuel Gauge

I have replace several gm fuel pump on suv, van, and truck I think that it just the way their making them is all screwy.

 
bee46's Avatar
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June 5th, 2007, 11:56 PM   #7  
RE: Erratic Fuel Gauge

ORIGINAL: jhale

I have a 2000 tahoe and the gas gauge started doing the same thing but after awhile it now goes from empty with the idiot light on to full then half full then quarter tankand all over the place. Its almost like I have a magic refilling gas tank. I have not had the fuel pump replaced so I know it not that.
I can definately trace mine back to the fuel pump replacement. I sitll have those that suggest it be a ground issue, but am contacting a GM Parts Dealer with the VIN of my Tahoe in an attempt to determine just exactly which pump was factory installed to make sure that the replacement pump is the correct pump. As it stands now, parts books state that AC/Delco pumps MU149, MU150, & MU148 are all listed as correct for this vehicle application.

 
tahoe yv's Avatar
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March 31st, 2010, 7:15 PM   #8  
Erratic Fuel gauge

Posted By: gamato I have a 1999 2-door 4wd Tahoe. I just had the fuel pump replaced and when I got the truck back, the fuel gauge is now erratic. It moves back and forth like the blinker was on or something, but not back and forth too far , just slightly. It doesnt jump all over the place and its not too noticable during the day. When I am driving at night and the gauges are lit up, it almost looks like its vibrating back and forth extremely fast like a humming bird almost. Now the mechanic even replaced the 1st new fuel pump assembly w/sending unit and the same thing is happening. It even does this with the truck off and the key turned to the on position. It didnt do this before I had the pump replaced and now no one can figure it out. Any help would be greatly appreciated. Thanks...
Gamato, Did you checked the Broadcast code in you fuel pump> it happens the same to me the Code was GAW and the new pump is GFU> I blame the codes but havent's found anybody to expalin this to me. I replace and old delphi pump with a new AC Delco MU150. Appreciate your comments.

 
lopezart69's Avatar
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August 12th, 2011, 9:58 AM   #9  
I have the same problem with my 99 suburban. It started after I changed the fuel pump.

 
justimagination's Avatar
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March 25th, 2012, 4:37 PM   #10  
Has anyone figured out this problem ?????????

 
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