85 S15 fuel gauge bounce - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Ynotnow817 · 06-30-2011, 12:32 PM

Just bought it and fuel gauge bounces even at stand still. Easy fix?
Thanks in advance

tucsonjwt · 06-30-2011, 06:16 PM

Was it an aftermarket "Spectra" brand sending unit? If so, there is no fix, unless you are electronics savvy and can fiddle with resistors (someone else posted a tech link on this, but is was beyond my skill/interest level.)
The aftermarket sending units, unlike AC Delco units, have imprecise resistors and react to every slosh in the fuel tank under motion, when stopping, turning, etc. If the gas gauge eventually settles down, then the sending unit will give you the correct fuel tank level at the end of the bounce cycle. Spectra ($45) bouncing gas gauge vs. AC Delco ($160) no bounce - your choice. I take the bouncing $45 gauge for my work truck.

Ynotnow817 · 07-03-2011, 09:57 AM

Sorry I wasn't clear. I just bought the truck. The gauge is original. I think. The bounce happens even at idle. Any thoughts?
Posted via Mobile Device

Tink · 07-07-2011, 02:38 PM

I have the same problem with my 89... even bounces at idle... from what tucsonjwt wrote, I gather it is the sending unit in the tank - not the gauge. Most likely, it was replaced at some point if the fuel pump was replaced.

68C15 · 07-09-2011, 06:48 AM

usually the problem is in the gauge. the film type resistor on the back between the 2 terminals fails. it is a dampening resistor.

06-30-2011, 12:32 PM	#1
Ynotnow817 Registered User Join Date: Nov 2009 Location: Arlington,TX Posts: 88	85 S15 fuel gauge bounce Just bought it and fuel gauge bounces even at stand still. Easy fix? Thanks in advance

06-30-2011, 06:16 PM	#2
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,189	Re: 85 S15 fuel gauge bounce Was it an aftermarket "Spectra" brand sending unit? If so, there is no fix, unless you are electronics savvy and can fiddle with resistors (someone else posted a tech link on this, but is was beyond my skill/interest level.) The aftermarket sending units, unlike AC Delco units, have imprecise resistors and react to every slosh in the fuel tank under motion, when stopping, turning, etc. If the gas gauge eventually settles down, then the sending unit will give you the correct fuel tank level at the end of the bounce cycle. Spectra ($45) bouncing gas gauge vs. AC Delco ($160) no bounce - your choice. I take the bouncing $45 gauge for my work truck.

07-03-2011, 09:57 AM	#3
Ynotnow817 Registered User Join Date: Nov 2009 Location: Arlington,TX Posts: 88	Re: 85 S15 fuel gauge bounce Sorry I wasn't clear. I just bought the truck. The gauge is original. I think. The bounce happens even at idle. Any thoughts? Posted via Mobile Device

07-07-2011, 02:38 PM	#4
Tink Registered User Join Date: May 2002 Location: VA Posts: 1,337	Re: 85 S15 fuel gauge bounce I have the same problem with my 89... even bounces at idle... from what tucsonjwt wrote, I gather it is the sending unit in the tank - not the gauge. Most likely, it was replaced at some point if the fuel pump was replaced. __________________ 69 Chevy C10 88 Sierra 02 2500 Suburban And too many S10s to list!

07-09-2011, 06:48 AM	#5
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: 85 S15 fuel gauge bounce usually the problem is in the gauge. the film type resistor on the back between the 2 terminals fails. it is a dampening resistor. __________________ Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card



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