1969 Fuel tank sending unit - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 6Likes
  • 1 Post By 69-Pace
  • 1 Post By emdoller
  • 1 Post By akxtreme
  • 1 Post By 69-Pace
  • 1 Post By emdoller
  • 1 Post By emdoller
 
LinkBack Thread Tools Display Modes
post #1 of 15 (permalink) Old Jul 14th, 18, 09:34 PM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
1969 Fuel tank sending unit

Lots of great info on this website debugging my fuel gage. My gauge is way to the right past full, somewhere around 3:00.

I removed the sending unit wire in the trunk and grounded the harness (wire running to the fuel gage) turned on the ignition and it went to empty. Good sign it’s not the gauge.

I then measured the resistance between the sending unit wire and the harness where it plugs in and got an open... no resistance at.

I haven’t gotten under the car yet but given the results thus far believe it’s:

1) the sending unit wire came off
2) the sending unit ground is off
3) the sending unit is broken

Does this seem right?

Ed
emdoller is offline  
Sponsored Links
Advertisement
 
post #2 of 15 (permalink) Old Jul 15th, 18, 05:11 AM
Admin/Super Moderator
Brian
 
69-Pace's Avatar
 
Join Date: Jun 2010
Location: Connecticut USA
Posts: 12,509
Garage
Re: 1969 Fuel tank sending unit

Yes Ed. Seems you have isolated the issue to the sending unit. A physical inspection of the ground at the rear of the tank strap, passenger strap would be the next point to look at. Us an alligator clamp and clip it to the ground and then clip the other end to a good ground and retest, if you have resistant then clean and reconnect the ground and test again. If you still have resistance you may have fixed the issue. I say may as even if you have resistance, the float of the sender may be stuck or gives faulty readings. Based on how much fuel you really think is in the tank, add or remove to change the resistance readings. If you get difference then you might be okay. If the change is minimal after changing the amount of fuel by at least three gallons or more then you will have to drop the tank and inspect the sender and or refurbish or replace it.

Brian
Vega$69 likes this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

1969 Z11 Pace Car - L48 350cid/300hp - 4 Speed Muncie 12 bolt rear.

Super Moderator Team Camaro
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
to send me a private message
69-Pace is offline  
post #3 of 15 (permalink) Old Jul 15th, 18, 07:05 AM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
Re: 1969 Fuel tank sending unit

Thanks Brian and thanks for the great write up. I will get under the car tomorrow and report back.

Ed
69-Pace likes this.
emdoller is offline  
 
post #4 of 15 (permalink) Old Jul 19th, 18, 12:27 PM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
Re: 1969 Fuel tank sending unit

I looked at the ground and it looked ok. To make sure, I removed the wire, sanded it and ran a jumper. No change. Measured the resistance between the sender wire and harness and itís open.

Iím assuming that means itís the sending unit. Anything else I should try before ordering parts?

Ed
emdoller is offline  
post #5 of 15 (permalink) Old Jul 19th, 18, 12:39 PM
Senior Tech
Robert
 
Join Date: Jul 2005
Location: Elizabeth, Colorado
Posts: 464
Garage
Re: 1969 Fuel tank sending unit

I think your best bet is to just order a new sending unit. You can order one for me while your at it.
emdoller likes this.

AKXtreme
69 Camaro L48 SS350
M20 4spd
akxtreme is offline  
post #6 of 15 (permalink) Old Jul 19th, 18, 02:36 PM
Admin/Super Moderator
Brian
 
69-Pace's Avatar
 
Join Date: Jun 2010
Location: Connecticut USA
Posts: 12,509
Garage
Re: 1969 Fuel tank sending unit

No you about covered it, there is the off chance that it is rotted off at the sender and may be able to be reconnected but maybe not and they are cheap.

FAIR WARNING I would bench test the NEW unit by hooking it up and grounding it BEFORE you install it. Some have been known to be duds out the factory door and nothing worse then draining a tank then to have to drain it twice.

When testing don't get hung up if when you move the float up you go way past the 90 ohms that full is it will just read full on the gauge.

Brian
emdoller likes this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

1969 Z11 Pace Car - L48 350cid/300hp - 4 Speed Muncie 12 bolt rear.

Super Moderator Team Camaro
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
to send me a private message

Last edited by 69-Pace; Jul 19th, 18 at 06:14 PM.
69-Pace is offline  
post #7 of 15 (permalink) Old Jul 19th, 18, 04:42 PM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
Re: 1969 Fuel tank sending unit

Thanks. Ordered the Ac Delco version given everything Iíve read on some of the repoís. Great idea on bench testing it. Should arrive in a week or so.

Ed
69-Pace likes this.
emdoller is offline  
post #8 of 15 (permalink) Old Jul 20th, 18, 06:07 AM
Gold Lifetime Member
Fred
 
77thor's Avatar
 
Join Date: Jun 2005
Location: Milwaukee, WI USA
Posts: 2,139
Re: 1969 Fuel tank sending unit

Quote:
Originally Posted by emdoller View Post
Thanks. Ordered the Ac Delco version given everything Iíve read on some of the repoís. Great idea on bench testing it. Should arrive in a week or so.

Ed

Just curious... Who did you order from??

1969 Camaro SS, 350(NOM), M21, 12 Bolt Posi, 01B LOS Build
1977 Camaro, 350(LM1), M20, 10 Bolt Posi, Purchased New, (SOLD)
77thor is offline  
post #9 of 15 (permalink) Old Jul 21st, 18, 06:47 PM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
Re: 1969 Fuel tank sending unit

Sorry for the delay. I ordered it from classic industries. They are having a 25% off sale.

Ed
emdoller is offline  
post #10 of 15 (permalink) Old Jul 26th, 18, 11:16 AM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
Re: 1969 Fuel tank sending unit

Got my new sender. Bench tested it and it worked. To make sure it fixed the problem I hooked it up to the car wiring and turned the key. Nothing happened. I then grounded the wire going to the gauge as this moved the needle last time I tried. It didnít move.

After scratching my head I decided to tap the gauge and that did it.

Put it all back together and itís working although I think the gushed is off about 1/8 of a tank. I can live with that especially because itís 1/8 less than whatís in the tank.

Thanks for the help especially Brian for the debug writeup.

Ed
69-Pace likes this.
emdoller is offline  
post #11 of 15 (permalink) Old Jul 26th, 18, 11:23 AM
Gold Lifetime Member
Dan
 
Join Date: Jan 2018
Location: California
Posts: 78
Re: 1969 Fuel tank sending unit

I'm helping a friend with a similar issue. First problem is we can't find the plug that connects to the back of the fuel gauge under the dash. Does anyone have a handy picture of this 3-prong connector?
I found the correct color wires going to the body harness connector under the dash and the wiring going to the fuel tank is all there but no sign of that fuel gauge connector and no evidence that it was cut out.... weird.
thegodown is offline  
post #12 of 15 (permalink) Old Jul 26th, 18, 04:02 PM Thread Starter
Senior Tech
Ed
 
Join Date: Jun 2004
Location: Northern CA
Posts: 422
Re: 1969 Fuel tank sending unit

All I have is the wiring diagram. It shows the wires and a three prong connector. I didnít get under my dash because I determined it was the sending unit by following Brianís guide.

Ed
emdoller is offline  
post #13 of 15 (permalink) Old Jul 26th, 18, 04:51 PM
Gold Lifetime Member
Dan
 
Join Date: Jan 2018
Location: California
Posts: 78
Re: 1969 Fuel tank sending unit

Thanks Ed.
thegodown is offline  
post #14 of 15 (permalink) Old Jul 26th, 18, 05:31 PM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 31,584
Garage
Re: 1969 Fuel tank sending unit

There is a pigtail connection in the trunk next to the lock structure.
You can troubleshoot from there, as in hooking up another sending unit or 0-100 ohm rheostat and ground to the wire going into the harness, and measure resistance referenced to ground with the wire going through the floor to the tank.

Give a man a rescued dog for the health of both their souls. May 2017 ROTM Winner - Thank you!
'
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CUBS - 2016 World Series Champions - maybe this year, 2019 ...
Everett#2390 is offline  
post #15 of 15 (permalink) Old Jul 27th, 18, 06:42 AM
Senior Tech
Ed
 
Join Date: Feb 2018
Location: Wheeling, WV
Posts: 365
Re: 1969 Fuel tank sending unit

Make sure you buy a quality sending unit if you replace it. Here are some options for you.....

https://www.jegs.com/webapp/wcs/stor...ersistYmm=true
ZEN357 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome