1998 GMC Savana - Gas Gauge FIXED

JBUTITTA · Post by **JBUTITTA** » Fri Jul 24, 2009 9:14 am

I replaced the fuel pump module (delco) for low pressure and hard start. The tank was only half full when I replaced pump. After replacement the tank reads full, lowered the tank, removed module, tested and found gauge will read half when float is down all the way. After 2 hours of diag I determined the cause is I have 8 volts instead of 5 on the purple sender wire. The wiring diagram shows pin 13 at the Vcm white connector to be the 5v ref wire. The problem is there is no wire at pin 13. In 1 diagram i see a fuel sender buffer module but cannot locate (Im thinking this is part of the module but not sure). At this point Im ready to sell the shop for 4 years of college at University of Wisconsin for my daughter (A/C brackets included), getting hair plugs and dying my hair. Any help would be greatly appreciated. jerry

ricmorin · Post by **ricmorin** » Fri Jul 24, 2009 9:43 am

1/2 ton, 3/4 ton or 1 ton? Which engine?

JBUTITTA · Post by **JBUTITTA** » Fri Jul 24, 2009 11:13 am

Sorry, 3500 with a 5.7 vin r motor. jerry

ricmorin · Post by **ricmorin** » Fri Jul 24, 2009 11:34 am

My diagram shows pin 19 on C3 VCM to be the 5v ref. Pin 13 on C3 VCM is return. I can fax you this diagram.

ricmorin · Post by **ricmorin** » Fri Jul 24, 2009 11:39 am

Also, only the diesel uses the buffer module. It needs that to use passlock to shut the fuel pump down during theft. I think in gas models they just shut of injector pulse.

JBUTITTA · Post by **JBUTITTA** » Fri Jul 24, 2009 12:10 pm

Thanks for helping Ric. I originally thought the same thing but while researching indentafix, several post indicated the purple wire is the 5v supply wire. I also dont have a wire in the #13 cavity. Totaly confused at this point. If I were still a drinking man Im sure a bottle of smirinoff would help solve this problem (for today at least).

ricmorin · Post by **ricmorin** » Fri Jul 24, 2009 12:12 pm

JBUTITTA wrote:Thanks for helping Ric. I originally thought the same thing but while researching indentafix, several post indicated the purple wire is the 5v supply wire. I also dont have a wire in the #13 cavity. Totaly confused at this point. If I were still a drinking man Im sure a bottle of smirinoff would help solve this problem (for today at least).

What is the actual date of manufacture? Maybe it's a half-year or something.

ricmorin · Post by **ricmorin** » Fri Jul 24, 2009 12:16 pm

Make sure it is C3. That should be the clear one.

steven kiser · Post by **steven kiser** » Sat Jul 25, 2009 2:35 am

i hope you checked plug for corrousion. there is another plug that messes up on the tranny cross member that i've had major problems with.

JBUTITTA · Post by **JBUTITTA** » Thu Jul 30, 2009 7:40 am

Finally got the van back into the shop today. The fix is for me to take a day off tomorrow and go golfing. This customer has 2 GMC vans. The one under his company account is the 98. His wifes is a 96 and is under his porsonal account. I had entered the wrong vehicle when the van was towed in, did not verify vin or plate (which I normaly do) and subsequently ordered the wrong pump. Thanks Ric for reminding me to check the build date. Im off to the driving range to fill up my bag with range balls (should save me $30 from buying new balls). Jerry

1998 GMC Savana - Gas Gauge FIXED

1998 GMC Savana - Gas Gauge FIXED

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 98 GMC Savana Gas Gauge

Re: 1998 GMC Savana - Gas Gauge FIXED