Another Fuel gauge question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jjtackleberry · 09-13-2011, 05:31 PM

I've read the other threads, but they are a bit like German stereo instructions.

When i put a tester on the sending unit post, its grounded. In other words, my meter tones when i have one lead on the sending unit post and the other on a ground.

when i take the wire off the post the gauge goes to 3 oclock. when the wire is on the post gauge reads empty. So the reading is the same on the wire, and the post.

Any help would be great.

JimKshortstep4x4 · 09-13-2011, 08:40 PM

You need a meter that reads out in ohms as the sending unit should read 0 to 90 ohms if it is working, (0=empty, 90=full).

Jim

jjtackleberry · 09-13-2011, 11:38 PM

Quote:

Originally Posted by JimKshortstep4x4

You need a meter that reads out in ohms as the sending unit should read 0 to 90 ohms if it is working, (0=empty, 90=full).

Jim

i do have a meter that reads ohms. I guess i'm not understanding whats going on with the sender.

wire off = gauge reads 3pm
wire on = gauge reads empty
meter shows ground at sender post
meter shows ground at wire

HELP?

Sammy · 09-13-2011, 11:55 PM

Pull the float assy. Take ohms reading picking up the float arm to simulate full should read the 90 ohms then at the bottom 0. During this process your checking only the float for correct readings so the feed wire should be off the post. If you are getting the correct readings your float is good. Trouble shoot the wire back to dash for breaks. If no breaks your problem is the dash Gage or a ground or something like that.
Posted via Mobile Device

Livrat · 09-14-2011, 12:07 AM

from your test, that tells me the fuel gauge is working.
I'll bet the float on the sender has a pin hole in it and it has filled full of gas and sunk (very common) this makes your gauge always read empty. Or it has come off the wire.
Either way you will have to pull the sender out of the tank to find out.

Legolas894 · 09-14-2011, 08:01 PM

...or it could be the resistor is bad on the sender. Mine was really scratchy. If you ground the sending wire, it should read empty. With if off, it will read more than full. Senders are pretty cheap. If you do take the sender out, you can check the resistance on it by moving the arm gently and not very far up or down.

dmack91 · 09-14-2011, 11:44 PM

Hopefully VetVette will sign in - he helped me on mine.

If memory serves, if your gauge is reading 9 o'clock with the wire attached, the sender is grounded and needs replacing.

09-13-2011, 05:31 PM	#1
jjtackleberry Registered User Join Date: Feb 2011 Location: kansas Posts: 306	Another Fuel gauge question I've read the other threads, but they are a bit like German stereo instructions. When i put a tester on the sending unit post, its grounded. In other words, my meter tones when i have one lead on the sending unit post and the other on a ground. when i take the wire off the post the gauge goes to 3 oclock. when the wire is on the post gauge reads empty. So the reading is the same on the wire, and the post. Any help would be great. __________________ '71 Chevy LWB all OG '86 Chevy LWB all OG It's all a matter of perception

09-13-2011, 08:40 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Another Fuel gauge question You need a meter that reads out in ohms as the sending unit should read 0 to 90 ohms if it is working, (0=empty, 90=full). Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

09-13-2011, 11:55 PM	#4
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: Another Fuel gauge question Pull the float assy. Take ohms reading picking up the float arm to simulate full should read the 90 ohms then at the bottom 0. During this process your checking only the float for correct readings so the feed wire should be off the post. If you are getting the correct readings your float is good. Trouble shoot the wire back to dash for breaks. If no breaks your problem is the dash Gage or a ground or something like that. Posted via Mobile Device __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

09-14-2011, 12:07 AM	#5
Livrat Member #1049 Join Date: Jun 2000 Location: Troy Montana Posts: 3,940	Re: Another Fuel gauge question from your test, that tells me the fuel gauge is working. I'll bet the float on the sender has a pin hole in it and it has filled full of gas and sunk (very common) this makes your gauge always read empty. Or it has come off the wire. Either way you will have to pull the sender out of the tank to find out.

09-14-2011, 08:01 PM	#6
Legolas894 Chemist under the hood... Join Date: Apr 2009 Location: Fort Erie,ON, Canada Posts: 617	Re: Another Fuel gauge question ...or it could be the resistor is bad on the sender. Mine was really scratchy. If you ground the sending wire, it should read empty. With if off, it will read more than full. Senders are pretty cheap. If you do take the sender out, you can check the resistance on it by moving the arm gently and not very far up or down. __________________ Current fleet: 2013 GMC Sierra, 5.3L, 4x4 1988 GMC Sierra, 305, Auto 1984 Jeep Grand Wagoneer, 360 V8 1997 VW Cabrio, 2.0L 2017 Toyota Rav4, 2.5L Stuff I wish I still had: 2013 Toyota Matrix [RIP] 1967 GMC 910 Fleetside, 283 V8 [1st Love-SOLD] 1987 Jeep Cherokee Laredo 4X4, 4.0 I-6 [SOLD} 1994 Chevrolet Caprice Classic, 5.7LV8 [SOLD] 1995 Chevrolet Astro AWD, 4.3L V6 (RIP) 1998 Chevrolet Suburban 4x4, 5.7L V8 [SOLD]

09-14-2011, 11:44 PM	#7
dmack91 Registered User Join Date: Jan 2011 Location: Redmond, OR Posts: 763	Re: Another Fuel gauge question Hopefully VetVette will sign in - he helped me on mine. If memory serves, if your gauge is reading 9 o'clock with the wire attached, the sender is grounded and needs replacing. __________________ 68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress



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