1969 Impala fuel sending unit - Impala Tech
General Tech For best results use forums below.

 
LinkBack Thread Tools
post #1 of 13 (permalink) Old 04-23-2010, 10:33 AM Thread Starter
 
 
Join Date: Sep 2009
Location: Ohio
Posts: 18
 
1969 Impala fuel sending unit

Hello all,
Once again I want to say thanks to everyone for the information. It really helps. I've got two questions today for everyone to ponper...

1. Drop the fuel tank on my 69. I pulled out the sending unit and it looks like a can that has a filter on the bottom of it. It appears to be a self contained unit. I admit that I haven't torn into it yet, but it seems strange. Was that normal on those big bodies back then? If so, do they still make them and/or will a new style fuel sending unit work? I've looked quickly at some sites and the only sending unit I have seen is for a big block(7.0). Part numbers may also help if anyone knows it off hand.

2. Tank appears to have some rust and gunk in it. It hasnt been started in 20 years so the gas smells like ****. What is the best way to clean it? After cleaing it, should I put some sort of liner in it to stop the chances of it ever happening again?

Details:
1969 Impala
350 4bbl a/c auto

Thanks as always
Dave
1969impalaDave is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old 04-23-2010, 01:20 PM
Senior Member
 
Join Date: Jan 2009
Location: Strongsville, Ohio
Posts: 256
Blog Entries: 14
 
Not sure on your sending unit it depends on engine. I bought an OER one. The catalog can be found here.
http://www.oerparts.com/Catalog/OER2...ogButton_Brand

POR makes a kit just for this.

http://www.stoprust.net/POR-15-Fuel-...-Kit-p-11.html
wogman75 is offline  
post #3 of 13 (permalink) Old 04-23-2010, 06:55 PM
Senior Member
 
Join Date: Apr 2008
Location: Lemont,Il
Posts: 200
 
Hey Dave,
Yes that is a "normal issue" sending unit. I have not seen a re-pop of that style. Does yours still work?? What you are going to find is that your sending unit has three connections on top and the other style has two. Question is do you need all the connections?? My 70 convertible has a supply,return, and vent that runs up into the trunk and back down under the car. The reason is that the gas cap is "not vented"...
due to the low filler neck it kept the fuel in the tank and not spewing out on launch.
I have not used any products that line the tank so I cannot comment on that. Tanks are available for the 69-70 cars.
Gary
BBDropTop is offline  
 
post #4 of 13 (permalink) Old 04-25-2010, 01:09 AM
Senior Member
 
Join Date: Jun 2009
Location: GA.
Posts: 402
 
I had my tank steamed and lined works fine no more rust particles in the filter. Also I had the canister type sending unit mine went bad but no repop made got a newer style works great. And that thing up in the trunk is a recycling cartridge it was suppose to give you better gas mileage I just eliminated mine.

Make: Chevrolet
Model: Impala
Year: 1971
Doors: 4
Motor: 400 V8
Tranny: TH350
71 Impala is offline  
post #5 of 13 (permalink) Old 05-16-2015, 10:02 AM
 
 
Join Date: Oct 2014
Location: Orlando, Fl
Posts: 7
 
Having the same Issues. The ethanol in today's gas has deteriorated my fuel sending unit and I no longer have a fuel gauge. Purchased a new one from Year One and when it arrived I started the work. Dropped the tank and instantly noticed my fuel sending unit differs drastically to the sending units sold today to replace them. They do not come with a return line, basically 2 lines a 3/8' send a 5/16" return and the tank is vented.

The return comes back from the fuel pump. Was this something Chevrolet did to vehicles with Air conditioning to keep the fuel pump wet so if you started the vehicle with the A/C on it didn't strain the motor due to a dry pump?? Cause only vehicles with A/C seem to have a return line.


But Today you cannot find a single replacement for sale and I'm really bummed as I would like to keep her original and don't want to start fabricating a new sending unit.


ANYONE have any answers??????????????????

Last edited by Drumfunken; 05-16-2015 at 11:29 AM.
Drumfunken is offline  
post #6 of 13 (permalink) Old 05-16-2015, 10:34 AM
Moderator
 
Join Date: Jan 2006
Posts: 12,421
 
Very few fuel pumps had a return line. No return at the pump no return at the tank. The only A/C Delco factory return line mechanical fuel pump I am familiar with was the 325 horse 396 that had return line when fitted with a Rochester QuadraJet carburetor. It supplied the carb with all the gas it could use and what it couldn't use was returned to the tank under reduced pressure from the pump via a second steel fuel line.

A mechanical pump is fixed in it's pressure by the spring inside the pump. It is the spring inside the pump and not the lever arm that pressurizes the fuel. The spring arm only sucks in the fuel as it moves. The spring above the diaphragm pushes the fuel out and up to the carb.

Since the spring never applies more pressure than the carb needle and seat can handle there is no need for a return line.

With electric pumps located next to and under the gas tank or fuel cell the pump pressurizes the fuel from 14 to 87 psi to push it forward and for it's use at that pressure with EFI if needed. Since a carburetor can not handle that kind of fuel pressure a return line is required. The return line returns all unused fuel to the tank at a high pressure and has to be segregated from the pick-up to keep the fuel from foaming.

In cars made before 1973 when cats and charcoal filters for gas tanks came on line there were only two lines in the pick-up the actual fuel line and the gas tank vent. This added a third line to the pick-up, but it wasn't a return line just a second vent for the gas tank (one allowed filling the tank, without it backing up, and the second line went foreword to the charcoal filter to hold all of the gas fumes until you started up the car. The added gas fumes helped the overlean smog era carbs to crank up and do nothing to impede performance so they shouldn't be removed (nor should you disable the PCV system, as it helps rather than hurts performance).

The rest of the junk that I rip off (spark control, thermostatic choke for hot air into the carb, etc all hits the trash bin when I had a car so equipped before I dropped in a real non-Smog era motor (which have lower compression, lean jetted carbs, and retarded timing distributors to pass the sniff test should they have been installed in your sixties era car as a replacement).

Big Dave
Big Dave is offline  
post #7 of 13 (permalink) Old 05-16-2015, 11:22 AM
 
 
Join Date: Oct 2014
Location: Orlando, Fl
Posts: 7
 
Quote:
Originally Posted by Big Dave View Post
Very few fuel pumps had a return line. No return at the pump no return at the tank. The only A/C Delco factory return line mechanical fuel pump I am familiar with was the 325 horse 396 that had return line when fitted with a Rochester QuadraJet carburetor. It supplied the carb with all the gas it could use and what it couldn't use was returned to the tank under reduced pressure from the pump via a second steel fuel line.

A mechanical pump is fixed in it's pressure by the spring inside the pump. It is the spring inside the pump and not the lever arm that pressurizes the fuel. The spring arm only sucks in the fuel as it moves. The spring above the diaphragm pushes the fuel out and up to the carb.

Since the spring never applies more pressure than the carb needle and seat can handle there is no need for a return line.

With electric pumps located next to and under the gas tank or fuel cell the pump pressurizes the fuel from 14 to 87 psi to push it forward and for it's use at that pressure with EFI if needed. Since a carburetor can not handle that kind of fuel pressure a return line is required. The return line returns all unused fuel to the tank at a high pressure and has to be segregated from the pick-up to keep the fuel from foaming.

In cars made before 1973 when cats and charcoal filters for gas tanks came on line there were only two lines in the pick-up the actual fuel line and the gas tank vent. This added a third line to the pick-up, but it wasn't a return line just a second vent for the gas tank (one allowed filling the tank, without it backing up, and the second line went foreword to the charcoal filter to hold all of the gas fumes until you started up the car. The added gas fumes helped the overlean smog era carbs to crank up and do nothing to impede performance so they shouldn't be removed (nor should you disable the PCV system, as it helps rather than hurts performance).

The rest of the junk that I rip off (spark control, thermostatic choke for hot air into the carb, etc all hits the trash bin when I had a car so equipped before I dropped in a real non-Smog era motor (which have lower compression, lean jetted carbs, and retarded timing distributors to pass the sniff test should they have been installed in your sixties era car as a replacement).

Big Dave



Its a 1969 350 TH350 with a Rochester, and air conditioning. changing the fuel sending unit to a newer one doesn't work cause it won't fit in tank tried that. Only the Canister style fits and is acurate, here is a photo of the sending unit. top and side shot
gascanister.jpg



There are definitely two lines going forward to the fuel pump and one is larger than the other 3/8 vs 5/16 the 5/16 comes back to the second line on the fuel sending unit.

I'd rather not start taking things out of a original numbers matching car if I absolutely don't have to. Somewhere someone has what I need.

WHere are you?????????
Attached Thumbnails
Click image for larger version

Name:	gascanister.jpg
Views:	475
Size:	24.3 KB
ID:	11098   Click image for larger version

Name:	can top.jpg
Views:	294
Size:	47.4 KB
ID:	11106  

Last edited by Drumfunken; 05-16-2015 at 11:27 AM. Reason: spelling
Drumfunken is offline  
post #8 of 13 (permalink) Old 05-16-2015, 11:47 AM
Moderator
 
Join Date: Jan 2006
Posts: 12,421
 
The smaller line is the vent for the tank. If you follow the small line up to the rear axle you will discover that it ends with a rubber hose that has a plastic button on the end. That is a one way valve that keeps water out of tank as it also vents the tank of air as you fill the tank at the service station.

Big Dave
Big Dave is offline  
post #9 of 13 (permalink) Old 05-16-2015, 11:59 AM
 
 
Join Date: Oct 2014
Location: Orlando, Fl
Posts: 7
 
Then please explain this??

The Tank has a Tube on the top passengers side I think that comes off the Side that I believe Vents it.

Here is a photo of the fuel pump and lines one coming forward and one returning.


IMG_0820.jpg.
Attached Thumbnails
Click image for larger version

Name:	IMG_0820.jpg
Views:	414
Size:	38.1 KB
ID:	11114  
Drumfunken is offline  
post #10 of 13 (permalink) Old 05-16-2015, 12:52 PM
Moderator
 
Join Date: Jan 2006
Posts: 12,421
 
That looks like a return line to me! Need to put it up on a hoist to verify it isn't going into some California EVAP control to be sure as California cars had all kinds of special emission control equipment on cars instead of attacking the problem of the real polluter which were the electrical power plants.

Big Dave
Big Dave is offline  
post #11 of 13 (permalink) Old 05-16-2015, 01:41 PM
 
 
Join Date: Oct 2014
Location: Orlando, Fl
Posts: 7
 
Its been traced a million times now and goes right back to the fuel sending unit.


Like I said we know its a return line we just can't find why its there and why we can't seem to find a replacement anywhere.

I had one guy in Detroit who said he had a fabricator who could make me one for $100 and he had already made several so I know I'm not the only person with this sending unit. Unfortunately he was out on injury leave and never returned to the shop so that option went out the window.

Back to square one.
Drumfunken is offline  
post #12 of 13 (permalink) Old 05-26-2015, 12:39 PM
 
 
Join Date: Oct 2014
Location: Orlando, Fl
Posts: 7
 
Ok so Found the correct answer to this Problem.

It was a Canadian made part and only came on Impala's with A/C to keep the fuel pump wet for those who would start there car with the A/C On.

The correct replacement part number is

Spectra Premium "FG106A"

It does not have the canister but has the return lines and proper 3/8" send and 1/4" return. It took stopping at a lof of dealerships till I finally found one in NJ that said I wasn't crazy and provided me this information. I have not ordered it yet but supposedly it is the replacement for the canister style sending units with the old canister type.

I will be ordering one soon and will let you all know whether or not it fits.
Wish me Luck!!!
Drumfunken is offline  
post #13 of 13 (permalink) Old 06-09-2015, 09:42 AM
Senior Member
 
Join Date: Nov 2010
Location: West Jefferson, Ohio
Posts: 270
 
The canister around the stock sending unit only does one thing, battle fuel slosh so the gauge doesn't move around so much while turning/stopping/accelerating. The replacement styles work fine and are designed like most other sending units in cars built in the last 30 or 40 years. The only drawback is the gauge will float around a bit, as most tanks with that style sending unit have some kind of baffle system in them.

'69 Impala 4-door hardtop
'70 Impala Custom coupe
AK99 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Impala 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 for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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