A little advice

[Iamtdg]

I posted in the welcome forum, but wanted to drop a couple of questions in here.

Bought an 87 Chevy C10 shortwide. Runs great, but a quick question.

Gas gauge doesn't work. Should just be the cable, right?

I haven't dug into yet because I am fairly new at this and didn't want to do work that wasn't needed.

Any advice?

[mongocanfly]

Quite possibly be the sending unit..check the wiring at sending unit first..

[Iamtdg]

Originally Posted by mongocanfly

Quite possibly be the sending unit..check the wiring at sending unit first..

I dug into it a little bit and don't think it's the gauge. I got it apart enough that I could move the needle by hand and moved it to full and back to empty and it went right back to half a tank. (I filled it up yesterday)

I will check the sending unit next.

Thanks.

[Iamtdg]

Sorry, I'm a newb, but is the sending unit the one that is on top of the gas tank?

And, I suppose I have to drop the tank to get to it?

[TKCR]

If you do a search on the forum, it will return a bunch of threads on this subject. Read through a few, they will offer up on what to look for. Some of the most common issue will be to check your ground wire.
BTW, Welcome to Forum!!!

[100%Chevy]

Originally Posted by Iamtdg

Sorry, I'm a newb, but is the sending unit the one that is on top of the gas tank?

And, I suppose I have to drop the tank to get to it?

Yes you do have to drop the tank!It's a royal pain in the butt!
But first,get all the gas out that you can to reduce the weight.
Another tip is to check the ground wire at the tank where it is connected to the frame.Corrosion here will cause funny readings.
When you drop the tank,(there's 8-3/8th's bolts holding it to the frame you must remove)not much hose or wires,so go easy.Some prefer to raise the bed!Now,clean the ground on the frame and check guage again.Should read correct.
Still bad?Now unplug the wire on the sending unit(one with the rubber boot on it).Ground it to a clean bare spot on the frame.With first ground wire still grounded.Should read full too.
I just today finished mine.I replaced both sending units with the Spectra brand from O''Reilly's.
Mike.

[Iamtdg]

Originally Posted by TKCR

If you do a search on the forum, it will return a bunch of threads on this subject. Read through a few, they will offer up on what to look for. Some of the most common issue will be to check your ground wire.
BTW, Welcome to Forum!!!

Thank you. For the welcome and the advice.

[Iamtdg]

Originally Posted by 100%Chevy

Yes you do have to drop the tank!It's a royal pain in the butt!
But first,get all the gas out that you can to reduce the weight.
Another tip is to check the ground wire at the tank where it is connected to the frame.Corrosion here will cause funny readings.
When you drop the tank,(there's 8-3/8th's bolts holding it to the frame you must remove)not much hose or wires,so go easy.Some prefer to raise the bed!Now,clean the ground on the frame and check guage again.Should read correct.
Still bad?Now unplug the wire on the sending unit(one with the rubber boot on it).Ground it to a clean bare spot on the frame.With first ground wire still grounded.Should read full too.
I just today finished mine.I replaced both sending units with the Spectra brand from O''Reilly's.
Mike.

Man, I'm hoping I can find a fix that doesn't involve dropping the tank, but obviously I will, if needed.

Thank you.

[cooperhw]

This is also the most common area that a mouse or rat will get up into and build a house. Above tank/under cab. While building that house they like to chew the wires the run front to back. Sometimes you can wiggle a coat hanger (old steel wire one) up into that area above the tank and see if any mouse house material comes out. If it does, wires are almost always chewed.

[Iamtdg]

Again, I did tear it apart enough to get to the needle and moved it by hand and it moved back to half a tank. So, would that still indicate sending unit, or more of a gauge issue?

[mongocanfly]

Don't mess with the gauge..more than likely its going to be the sending unit or wiring at the sending unit..easiest way is pick bed up..take the hold down bolts out on the tank side and loosen the ones on opposite side (really loose)..you can then tilt bed by lifting it and sticking a 2x4 in there to hold it up at an angle..you should be able to work on it from there...much easier than trying to pull a tank full of gas.
..remember..that's a gas bomb your working on...

[TKCR]

Yes, be safe!! We don't want to hear about losing new members, well any members.

[mongocanfly]

BE SAFE..no kidding..and this is coming from a man that had 5 gallons of gas blow up in my face...not fun

[Keith Seymore]

Originally Posted by mongocanfly

Don't mess with the gauge..more than likely its going to be the sending unit or wiring at the sending unit..easiest way is pick bed up..

- This - x2

K

[Iamtdg]

Originally Posted by mongocanfly

Don't mess with the gauge..more than likely its going to be the sending unit or wiring at the sending unit..easiest way is pick bed up..take the hold down bolts out on the tank side and loosen the ones on opposite side (really loose)..you can then tilt bed by lifting it and sticking a 2x4 in there to hold it up at an angle..you should be able to work on it from there...much easier than trying to pull a tank full of gas.
..remember..that's a gas bomb your working on...

Good advice. I wasn't particularly looking forward to dropping the tank. This sounds much easier. The ground for the sending unit should connect to the frame somewhere pretty close to where the sending unit is, correct? So, I should have access to most of the wiring by doing this?

[tucsonjwt]

Since you are new to the site, you can search "gas gauge, fuel sending units, gas tanks" etc. and get some detailed information on this subject.

Here is my experience. I had a gauge that never read correctly. I dropped both tanks (I have dual tanks) and replaced the sending units. Still incorrect reading on the gas gauge. I replaced the gas gauge and that fixed the problem.

In my case, I used aftermarket Spectra brand sending units. While those units send the correct fuel level signal to the gas gauge, the gas gauge needle bounces then the vehicle is in motion, and it takes a few minutes for the gas gauge to settle down to the correct reading when the vehicle is not moving.

I believe that AC Delco sending units will not cause the gas gauge to bounce. AC Delco units cost about $150 per unit, Spectra units are about $50 per unit. For the price difference, I will accept the bouncing units while in motion.
Others will say that the gas gauge is the problem, not the sending units.

Dropping the tank is not difficult. You can read elsewhere on this website about different ways to drop the tanks. Obviously, the tanks should be as empty as possible. My method:

- Place concrete blocks and 2x4s or 1x4s under the front and rear of the
tank until they are snug.
- Squirt penetrant (Liquid Wrench, PB Blaster, WD 40 penetrant, etc.) on the
mounting bolts. There are 8 mounting bolts total (4 on the front bracket, 4
on the rear bracket. The bolts are driven into captive nuts on the mounting
brackets, so you only need one wrench to remove them. Use a ratchet
extension or multiple extensions as required on the bolts.
- When the bolts are removed, you can start to remove the wood and
concrete blocks from under the tank. Remove the rear blocks first, until
you can get your hand up above the tank and reach the sending unit on
the top of the tank. Use a flat blade screw driver to release the rubber
capped button connector. Unscrew the bolt for the grounding strap which
is attached to the frame rail. You should be able to remove all of the
electrical connectors with the tank still in place and resting on the
remaining blocks. (You can remove the small blocks under the front of
the tank and leave it resting on the concrete blocks only.)
- When you have room above the tank, you can use a flat blade
screwdriver to disconnect the radiator clamps around the rubber
filler hose, and the smaller hose which is the vent hose.
- When everything is disconnected, you can remove all of the remaining
blocks, one at a time, until the tank is on the ground. You can then
replace the sending units.
- The sending units are attached to the tank by a lock ring and a rubber
gasket below. You tap the upturned tab on the lock ring with a flat
blade screwdriver and hammer. Use AC Delco replacement gaskets
when installing the new sending unit. (The Spectra gaskets are more
of a generic O ring and not shaped to fit the slot in the top of the
sending unit like the Delco units are.)
- Installation is the reverse of removal, as all the shop manuals say.

[cadillac_al]

I dunno, everybody is different. I have removed beds and dropped gas tanks by myself and dropping tanks seems easier to me. If there are a lot of guys around then removing a bed might be easier. I disconnect the hoses and ground wire inside the frame and leave them on the sending unit when I drop it. I never drop one with gas in it. You want it as empty as possible to make it easier on yourself.