Fuel sender failing ?
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Fuel sender failing ?
(‘68 L68 427 )
I took my car out yesterday and it had a half tank when I left home and in about 45 minutes worth the gauge was near empty on the gauge.
I rolled it in for gas and expected to put in at least 18 gallons but to my surprise it topped off at just over 10 gallons. From full to half on the gauge it seemed normal but from half a tank on the gauge it dropped much faster. It would seem a half tank on the gauge is three quarter and empty is a half tank.
I bought the car out of a barn where it had been stored for more than three years with a quarter tank of foul gas. Does all of this add up to and makes sense for a failing sender ?
I took my car out yesterday and it had a half tank when I left home and in about 45 minutes worth the gauge was near empty on the gauge.
I rolled it in for gas and expected to put in at least 18 gallons but to my surprise it topped off at just over 10 gallons. From full to half on the gauge it seemed normal but from half a tank on the gauge it dropped much faster. It would seem a half tank on the gauge is three quarter and empty is a half tank.
I bought the car out of a barn where it had been stored for more than three years with a quarter tank of foul gas. Does all of this add up to and makes sense for a failing sender ?
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Well, really, no.
it's easy enough to test your sending unit with a ohm meter. But your symptoms sound like high resistance through 50 year old wires through the car.
It's a 90 ohm sending unit.
My c3 has a connector for the sending unit in the left quarter panel, your 68 I believe, (I'm no expert on 68's). Has the sending unit going into the bottom of the tank. So, connect your ohm meter to the sending unit post and a good ground. Have a helper hook the float arm with a coathanger or similar. Doing this with a nearly empty tank would be good. Have the helper slowly raise the float as you watch the resistance. Should swing from near zero to 90 ohms progressively.
a dirty ground could cause this. High resistance through old internally corroded wiring could cause this. But it really doesn't sound like the sending unit itself. Which is just a rheostat switch with a float arm.
Test switch, go from there.
it's easy enough to test your sending unit with a ohm meter. But your symptoms sound like high resistance through 50 year old wires through the car.
It's a 90 ohm sending unit.
My c3 has a connector for the sending unit in the left quarter panel, your 68 I believe, (I'm no expert on 68's). Has the sending unit going into the bottom of the tank. So, connect your ohm meter to the sending unit post and a good ground. Have a helper hook the float arm with a coathanger or similar. Doing this with a nearly empty tank would be good. Have the helper slowly raise the float as you watch the resistance. Should swing from near zero to 90 ohms progressively.
a dirty ground could cause this. High resistance through old internally corroded wiring could cause this. But it really doesn't sound like the sending unit itself. Which is just a rheostat switch with a float arm.
Test switch, go from there.
Melting Slicks
Joined: Dec 2014
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From: Central UT
Hey LtMike - this link should help. http://repairs.willcoxcorvette.com/1...-can-tell-you/
I had the same type issue on our '68. After testing various items, I ended up replacing the sending unit and it works perfectly now. Not hard to do if that's what it comes to. Run the gas down to about 3-4 gallons (or less); siphon the tank dry (I siphoned, you can also unhook the rubber gas line and empty it that way - I found it very easy to siphon); remove the ring on the sending unit that is on the bottom of the tank; insert new sending unit and new gasket; clean and hook up connections; replace the short rubber fuel line while you're at it; put siphoned gas back in; and have fun.
Best of luck, hope the link helps. Paul
PS: I don't know what happened with Ernie Willcox. I know he was ill, but I must have missed the updates. I spoke with him several times and he was always very helpful to me.
I had the same type issue on our '68. After testing various items, I ended up replacing the sending unit and it works perfectly now. Not hard to do if that's what it comes to. Run the gas down to about 3-4 gallons (or less); siphon the tank dry (I siphoned, you can also unhook the rubber gas line and empty it that way - I found it very easy to siphon); remove the ring on the sending unit that is on the bottom of the tank; insert new sending unit and new gasket; clean and hook up connections; replace the short rubber fuel line while you're at it; put siphoned gas back in; and have fun.
Best of luck, hope the link helps. Paul
PS: I don't know what happened with Ernie Willcox. I know he was ill, but I must have missed the updates. I spoke with him several times and he was always very helpful to me.
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Well, really, no.
it's easy enough to test your sending unit with a ohm meter. But your symptoms sound like high resistance through 50 year old wires through the car.
It's a 90 ohm sending unit.
My c3 has a connector for the sending unit in the left quarter panel, your 68 I believe, (I'm no expert on 68's). Has the sending unit going into the bottom of the tank. So, connect your ohm meter to the sending unit post and a good ground. Have a helper hook the float arm with a coathanger or similar. Doing this with a nearly empty tank would be good. Have the helper slowly raise the float as you watch the resistance. Should swing from near zero to 90 ohms progressively.
a dirty ground could cause this. High resistance through old internally corroded wiring could cause this. But it really doesn't sound like the sending unit itself. Which is just a rheostat switch with a float arm.
Test switch, go from there.
it's easy enough to test your sending unit with a ohm meter. But your symptoms sound like high resistance through 50 year old wires through the car.
It's a 90 ohm sending unit.
My c3 has a connector for the sending unit in the left quarter panel, your 68 I believe, (I'm no expert on 68's). Has the sending unit going into the bottom of the tank. So, connect your ohm meter to the sending unit post and a good ground. Have a helper hook the float arm with a coathanger or similar. Doing this with a nearly empty tank would be good. Have the helper slowly raise the float as you watch the resistance. Should swing from near zero to 90 ohms progressively.
a dirty ground could cause this. High resistance through old internally corroded wiring could cause this. But it really doesn't sound like the sending unit itself. Which is just a rheostat switch with a float arm.
Test switch, go from there.
guess I pull the carrier back down and start with cleaning up the connections. Maybe replace the ground wire to the sender.
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Good place to start. And while it's down very easy to test with a ohm meter. 50 year old wiring can play games with resistance reading gauges. And Automotive wiring didn't get upgraded to higher quality until the late 90's.
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A good example of how corrosion can play with conductivity was with my turn signals. The oil pressure gauge leaked at the fitting and fouled everything including the flasher. It’s connections were fouled enough to limit it making the signals flash like there was a bulb out or had trailer lights plugged in. With clean connections it was back to normal. I’m hoping it’s that easy with the fuel sender. I’ll take a reading without doing anything then clean it up. Hopefully I’ll see a difference. If not I’ll run a separate ground wire to the sender and check again.
