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Gas leak and fuel gauge reading empty...
Posted by: bentley26 ()
Date: January 27, 2012 12:32AM

Went to start the Corvair for the first time in a couple of weeks... Fired right up, however the gas gauge was reading empty. When I filled the tank, it only took about 3 gallons, of which about 1 gallon hit the pavement.

Leak is not coming from the sender unit... Looks like from the top of the tank? Also, sender unit was replace last year, and has worked fine since. Can the leak also impact the sender's ability to function? Thanks!

Christopher
1965 Monza Sedan 110 "Air Vair."

Fort Collins, CO

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Re: Gas leak and fuel gauge reading empty...
Posted by: Yenkos66 ()
Date: January 27, 2012 12:38AM

Sounds like u need a filler neck hose. Check ground maybe for the sending unit

Alex Moats
Wichita KS
68 500 140 4spd
68 500 110 3spd
Duane Grimm always remembered rip

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Re: Gas leak and fuel gauge reading empty...
Posted by: acardon ()
Date: January 27, 2012 02:28AM

The float probably sprang a leak and filled with gas. You have to take the sender out to fix the leak, so check the float. A bad ground will NOT cause an empty reading.

The Trunk Belongs in Front, Ask Any Elephant
Caution: Images in This Mirror May be Waterpumpers
Don
NTCA....DFW,TEXAS
66 Monza 1 owner

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Re: Gas leak and fuel gauge reading empty...
Posted by: bentley26 ()
Date: January 27, 2012 02:53AM

Thanks for the feedback! Will a float leak also explain the gas leak on the top of the tank?

Christopher
1965 Monza Sedan 110 "Air Vair."

Fort Collins, CO

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Re: Gas leak and fuel gauge reading empty...
Posted by: MattNall ()
Date: January 27, 2012 03:02AM

Nope.. float is INSIDE the tank

Most likely the two connector hoses are rotten... easy fix..





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Gas leak and fuel gauge reading empty...
Posted by: bentley26 ()
Date: January 27, 2012 03:05AM

And the connector hoses would prevent the sender/fuel reading from working? Thanks again... Don't know what I'd do without this forum!!!!

Chris

Christopher
1965 Monza Sedan 110 "Air Vair."

Fort Collins, CO

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Re: Gas leak and fuel gauge reading empty...
Posted by: MattNall ()
Date: January 27, 2012 03:07AM

Nope!! most likely unrelated.. just a coincidence!





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Gas leak and fuel gauge reading empty...
Posted by: bentley26 ()
Date: January 27, 2012 03:17AM

Okay... Will check the hoses and drop the tank. See what I see and report back...

Christopher
1965 Monza Sedan 110 "Air Vair."

Fort Collins, CO

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Re: Gas leak and fuel gauge reading empty...
Posted by: Yenkos66 ()
Date: January 27, 2012 05:16AM

Most likely the hose has been rotted for a while but only leaks when filled all the way. I have had that happen twice to my cars. Had one for a month b4 I filled it for the first time and lost about a gallon cuz the hose was rotten

Alex Moats
Wichita KS
68 500 140 4spd
68 500 110 3spd
Duane Grimm always remembered rip

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Re: Gas leak and fuel gauge reading empty...
Posted by: bentley26 ()
Date: January 27, 2012 06:15PM

Is a float repairable, or would it need to be replace, assuming it is the problem? Just want to make sure I have the correct parts on-hand before I start taking things apart. Thanks!

Christopher
1965 Monza Sedan 110 "Air Vair."

Fort Collins, CO

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Re: Gas leak and fuel gauge reading empty...
Posted by: jimmyo ()
Date: January 27, 2012 07:18PM

sometimes they're repairable, new floats are under 10 bucks at clarks.

Jim O'Connor
45 miles north of The Bronx, N.Y.
1962 Greenbrier 110 4spd
1964 Monza Convertible 110 PG
"Wherever you go....There you are"


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Re: Gas leak and fuel gauge reading empty...
Posted by: bentley26 ()
Date: January 27, 2012 10:49PM

Just fired the car up again... Fuel needle moved from E to 1/16th, then back to E. Sender bad?

Christopher
1965 Monza Sedan 110 "Air Vair."

Fort Collins, CO

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Re: Gas leak and fuel gauge reading empty...
Posted by: Chris Lampe ()
Date: January 27, 2012 10:55PM

Christopher,

Quick check to see if the gauge is working correctly is to remove the wire from the sender then turn on the key and observe the gauge, then ground the sending wire to the chassis and observe the gauge. I don't recall which way is which right now but it should be obvious if the gauge is working. One way should send the gauge to full and the other will show empty. There's really no way to check the sender until it's out of the tank.

Chris
Rowlett, Tx
NTCA - North Texas Corvair Association
CORSA
'64 Monza 'vert

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Re: Gas leak and fuel gauge reading empty...
Posted by: Tom Z ()
Date: January 29, 2012 02:03PM

..ground wire from the sender to the rusty panel needs to be replaced,,I run a new,longer wire inside,along the wiring harness up the toe-board cover..disconnect the tan sender wire,,gauge will go 'full' with Ign key ON, 'empty' when it's grounded..bad DASH cluster ground will not let the gauge move at all (IIRC..)

Tom Z,,Rochester NY


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Re: Gas leak and fuel gauge reading empty...
Posted by: VegasVair ()
Date: January 29, 2012 02:45PM

Here's a review of how the Corvair fuel gauge and tank sender work.


All 1960-1969 Corvair fuel gauges work the same way. There are two major parts to the fuel gauge system. There's the gauge with the needle you see in the dashboard and there's a float with a sender inside the fuel tank. The gauge and the sender are connected by electrical wiring.

Anybody can see what the gas gauge in the dashboard does, but what about the float and sender inside the fuel tank? The float rides up and down inside the tank depending on how much gasoline is in there. The float is connected to the sender which allows a weak electrical current to pass through the gauge when the tank is full and a strong electrical current to pass through the gauge when the tank is empty. The sender is what's known as a variable resistor. In 60-64 cars the sender resistance is 0 to 30 ohms. In 65-69 cars the sender resistance is 0 to 90 ohms.

The fuel gauge needle is mounted between two magnetic coils. One coil is on the "F" side of the gauge and the other is on the "E" side of the gauge. Both coils are wired to the ignition circuit and receive battery voltage whenever the ignition switch is on.

The magnetic coil that pulls the needle toward F (Let's call this the F coil) is grounded at the instrument panel and applies a constant magnetic force to the needle. The magnetic coil that pulls the needle toward E (Let's call this the E coil) has more windings for greater magnetic strength and is grounded through the variable resistor in the sender attached to the fuel tank float.

When the fuel tank is full the resistance in the sender is high (30 or 90 ohms) which reduces electrical current and magnetic strength in the fuel gauge E coil allowing the F coil to pull the gauge needle to F.

When the fuel tank is nearly empty and the float is near the bottom of the tank the resistance in the sender is at 0 ohms. The fuel gauge E coil receives full current, has enough magnetic strength to overcome the strength of the F coil and pulls the gauge needle to E.

When the ignition switch is turned off both fuel gauge coils lose power, magnetic force drops, and the needle remains where it is.

If there is a break in the tank sender wiring or a failure of the tank sender that creates an open circuit, the fuel gauge F coil will not be balanced by any magnetic force from the E coil and the needle will be pulled to the right beyond the F mark on the gauge when the ignition switch is on.

If there is a break in the wiring to the F coil or a poor electrical ground on the dash, the needle will be pulled to the left beyond the E mark on the gauge when the ignition switch is on, or the needle may move erratically when the dash lights, turn indicators, or other electrical systems are operated.

Credit for most of the information here goes to Dale Dewald who is a regular contributor to the Virtual Vairs internet email list.

65 Corsa 140/4 A/C convert.
CORSA+Vegas Vairs

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Re: Gas leak and fuel gauge reading empty...
Posted by: Nickshu ()
Date: July 09, 2013 07:58PM

Resurrecting an old thread....I have the same problem, and I live in Fort Collins, CO also (But I see the OP has not posted anything in over a year).

Sooo...new to me '64 MSC. Filling up with gas for the first time (gauge says empty). Next thing I know gas is poaring out inboard of the driver's side front wheel.

So the garage (and hence the house) reeks of gas now. Wife is not happy. angry smiley

Tonight I am going to cut the fuel line and drain the tank to hopefully reduce the gas smell. Then I'll be removing the tank to inspect it and the area and go from there!

Any tips on tank removal on an EM? My guess is the filler flex/rubber hose will just separate as the tank comes down. My big question is can you drop the turbo fuel return line with the tank, then disconnect it? It appears that it's way up there with very little space to get in there. How high do I have to get the car? I have 12 ton jackstands as well as stacks of 2x12's that I can space them up higher with.

Thanks!

Nick

1964 Monza Spyder Convertible #435 - Rotisserie restoration in progress
Check out my restoration thread here: [corvaircenter.com]



Edited 1 time(s). Last edit at 07/09/2013 08:03PM by Nickshu.

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Re: Gas leak and fuel gauge reading empty...
Posted by: MattNall ()
Date: July 09, 2013 08:06PM

Filler tube hose is leaking..... typical....


Raise the from of the car at least 20" you may need to remove the anti-swaybar.. or at least rotate it.


Theoretically the filler neck comes down with the tank...but the factory installed the tank BEFORE the front suspension!





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Gas leak and fuel gauge reading empty...
Posted by: Nickshu ()
Date: July 10, 2013 02:16AM

Thanks Matt.

So I got the car up on jackstands tonight and drained the gas tank. It was nearly full!! I pulled about 12-13 gallons of fuel from it.

Soooo...my gas gauge doesn't work. It's pegged at about empty. I checked the ground on the sender and it's good. Sender and gas tank look like they were replaced by the PO. Tank is black with no rust and only a few scratches. Sender looks new(er) and shiny.

Interesting finding...the flex hose that I thought was disintegrating looks OK, but it appears the PO (or the PO's mechanic) replaced it with some universal hose (not specific/correct hose) as there are three (yes three!!) hose clamps wrapped around the top of the hose on top of each other, apparently trying to get it to seal. spinning smiley sticking its tongue out So when the tank was filled nearly full gas poared out of the poor upper seal on the generic flex hose.

I will drop the tank this weekend and take inventory of parts to replace including the correct hose(s).

What should I check next on the gas gauge to make sure it's a bad sender?

Nick

1964 Monza Spyder Convertible #435 - Rotisserie restoration in progress
Check out my restoration thread here: [corvaircenter.com]



Edited 1 time(s). Last edit at 07/10/2013 02:17AM by Nickshu.

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Re: Gas leak and fuel gauge reading empty...
Posted by: MattNall ()
Date: July 10, 2013 02:58AM

1 Correct size is 1-3/8" ID Soft hose.... and 1/2" for the ventline.

2 With wire removed from sender... turn key ON.... needle should go to FULL... if not the problem is in the dash wiring / gauge / lead [ shorted to ground ]

Just the opposite of most 60's crs...

3 When the tank was full.... you should've put an ohmmeter on the sender and ground...

0-30 ohms for your EM.... 0 is full... 30 is empty....

And watched as you drained it..

Now... remove the sender and move the float arm... and watch the meter....

Many times when people siphon gas out of the tanks they hit the float... and it falls off! You'll see..





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Gas leak and fuel gauge reading empty...
Posted by: steve c goodman ()
Date: July 10, 2013 03:04AM

I too will guess whoever replaced the filler neck hose couldn't find the correct diameter wherever they were. They used oversize and thus the extra clamps.

As an aside, there is a club here in Denver and numerous members live in Ft. Collins/Loveland/Longmont. You need to be a part of it, possibly someone up there has a float and the hose. I have hose at my shop but not sure about a float.

Sincere regards, Steve

1962 spyder 3.0L turbo 1967 monza 110/4
1968 monza 110/4 1971 amante gt 110/4

Golden, Colo. CORSA/RMC/PPCC

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