67 Impala fuel tank sending unit?

[GSGregg]

Howdy, all!

Impala 2-door fastback coupe; 327 / 275HP (Quadrajet); THM400; Gold everywhere except for the black vinyl top. A little over 231,000 miles, and needs everything, especially after sitting jacked up for thirteen years with a ground-up rear end. A garage replaced the pinion seal many years ago, but it was still noisy so I had the axle overhauled---but it was STILL noisy, and the car was relegated to short trips with the appearance of a new '86 Buick Century. Fast forward to 2003.

While rebuilding the trans in my '66 Skylark Gran Sport, something in the Impala's rear 'slipped', and the noise got horrendous. Still needing a few trans parts, I stuffed as much 90w in as would fit, drove about 30 miles round-trip, came back and finished the GS trans the next day. The GS came down and the Impala went up---for thirteen years, while I sought the time, decided what I wanted to do, borrowed the use of a large mill-and-drill and made a pair of .166-inch side-bearing spacers (field-service parts were .160", NLA) to go with a sparse selection of shims I was able to dig up. Then I found where the noise came from; the left shims put in by the garage totaled .010" less than the right ones, and backlash was way too high; when I reversed them, backlash fell right where it belonged! The garage switched the shimpacks during the overhaul all those years ago, and let it out the door without checking first!

I was happy to take my chances with the gearset, as the inevitable tooth scoring took place away from the center of contact, and I'm pleased to note that the rear end is quiet---for the first time in over thirty years!

But, enough about that; the reason I originally wanted to post is, thirteen years of sitting dry killed the fuel tank sending unit and it's an enclosed, sliding-float (anti-slosh?) type instead of the pivoting-arm type. Can someone with an appropriate parts book find out if there are incompatibilities that would keep a pivoting-arm type sender from being used? Also, if I could get the part number for the type I described, it may come in handy with someone who doesn't really know "what's in that old box on the top shelf....."

Sorry for the long gust of wind; thanks for reading!

Gregg

[j cAT]

Originally Posted by GSGregg

Howdy, all!

Impala 2-door fastback coupe; 327 / 275HP (Quadrajet); THM400; Gold everywhere except for the black vinyl top. A little over 231,000 miles, and needs everything, especially after sitting jacked up for thirteen years with a ground-up rear end. A garage replaced the pinion seal many years ago, but it was still noisy so I had the axle overhauled---but it was STILL noisy, and the car was relegated to short trips with the appearance of a new '86 Buick Century. Fast forward to 2003.

While rebuilding the trans in my '66 Skylark Gran Sport, something in the Impala's rear 'slipped', and the noise got horrendous. Still needing a few trans parts, I stuffed as much 90w in as would fit, drove about 30 miles round-trip, came back and finished the GS trans the next day. The GS came down and the Impala went up---for thirteen years, while I sought the time, decided what I wanted to do, borrowed the use of a large mill-and-drill and made a pair of .166-inch side-bearing spacers (field-service parts were .160", NLA) to go with a sparse selection of shims I was able to dig up. Then I found where the noise came from; the left shims put in by the garage totaled .010" less than the right ones, and backlash was way too high; when I reversed them, backlash fell right where it belonged! The garage switched the shimpacks during the overhaul all those years ago, and let it out the door without checking first!

I was happy to take my chances with the gearset, as the inevitable tooth scoring took place away from the center of contact, and I'm pleased to note that the rear end is quiet---for the first time in over thirty years!

But, enough about that; the reason I originally wanted to post is, thirteen years of sitting dry killed the fuel tank sending unit and it's an enclosed, sliding-float (anti-slosh?) type instead of the pivoting-arm type. Can someone with an appropriate parts book find out if there are incompatibilities that would keep a pivoting-arm type sender from being used? Also, if I could get the part number for the type I described, it may come in handy with someone who doesn't really know "what's in that old box on the top shelf....."

Sorry for the long gust of wind; thanks for reading!

Gregg

see if a newer type will work like the 92-96 caprice/impala/buick pumps will fit. same type fuel tank . you could also see if the fuel tank on the newer will fit in the 67.

[GSGregg]

Originally Posted by j cAT

see if a newer type will work like the 92-96 caprice/impala/buick pumps will fit.

Thanks, j cAT;

1994 Mitchell Manuals specifies all MFI fuel pressures are 41-47 PSI except 4.6L and 4.9L (40-50 PSI). I wonder whether the Q-Jet needle valve would hold against that kind of pressure, but it may not matter, because I have some notes from the "I'll Be Darned" Department:

I succeeded in getting the unit apart, and merely have to replace an insulator that couldn't take the force of pressing out the terminal stud (well.....I thought it was necessary.....), locate a filter sock for 3/8" tube, and a 3/8" push-retainer. I wired up the sender and manually set the float in different positions, and the gauge responded perfectly. Turns out that the open-circuit condition was due to one of the float's contact fingers being end-jammed and deformed---maybe even during original assembly---and it finally lost contact after 230K miles (?!)
Anyway, the re-formed finger is on the left in the photo.....

Oh, yeah---I pressed out the stud thinking that dissimilar metals had electrolyzed, corroded away their connection and needed cleaning.....and then I noticed the bent contact finger (Grrrr)

Thanks for the suggestions;

Gregg

[j cAT]

I was suggesting the 94-96 type tank fuel pump assy as a way to get the sender to work. the fuel pump motor could be removed and just use the sender/filter sock with some modifications along with a fuel tank being non metal to handle the alcohol fuel. I was thinking that the sender may have just needed a good cleaning. being stored a long time the fuel will leave residues that damage the parts. I use fuel conditioners and MMO in the fuel of the fuel tanks of engines not used often no corrosion. I believe the Q JET input pressure is about 7 PSI, so 45PSI would be too much for it to handle also the 67 does not have a return line .

Pictures show the rust not good , because of the alcohol ... bad for carb..I would put a bigger filter in line to the carb .

[GSGregg]

Originally Posted by j cAT

...the fuel pump motor could be removed...

DOH! Guess I took things too literally.....

Bigger filter; agreed. I put one in the hose in front of the stock pump, anticipating what the sock may have turned into.....turns out it rotted around its connector and fell neatly into the tank without a lot of fragments. After I blow out the line front-to-back and put on a new sock, I'll get rid of the extra filter.

Classic Industries, in Huntington Beach, CA, under an hour's drive from me, sells '67 gas tanks (only one sedan model) and '67-'70 senders (only pivoting-arm) and told me that the pivoting arm wouldn't work properly (obstructed? There are no baffles in the tank) and the gauge wouldn't read properly. Oh, well.....

Marvel...yeah, good stuff. Also, maybe lucky that the gas in this tank was 2003 issue, as my GS which was down Sept 2010 to Jan 2014 really lost a lot of what fuel 'economy' it had. Increased ethanol content during that time?

[j cAT]

Originally Posted by GSGregg

DOH! Guess I took things too literally.....

Bigger filter; agreed. I put one in the hose in front of the stock pump, anticipating what the sock may have turned into.....turns out it rotted around its connector and fell neatly into the tank without a lot of fragments. After I blow out the line front-to-back and put on a new sock, I'll get rid of the extra filter.

Classic Industries, in Huntington Beach, CA, under an hour's drive from me, sells '67 gas tanks (only one sedan model) and '67-'70 senders (only pivoting-arm) and told me that the pivoting arm wouldn't work properly (obstructed? There are no baffles in the tank) and the gauge wouldn't read properly. Oh, well.....

Marvel...yeah, good stuff. Also, maybe lucky that the gas in this tank was 2003 issue, as my GS which was down Sept 2010 to Jan 2014 really lost a lot of what fuel 'economy' it had. Increased ethanol content during that time?

with my 84 camaro I do disconnect the fuel line up front in the engine bay and drain then suck out all the old fuel after it starts to get too old even with the MMO and the double dose of the stabilizer. removal of the fuel tank I don ot want to do on this !

[GSGregg]

Small world, j cAT;

One of my projects was my nephew-in-law's 2.8L version of an '82-or-so Camaro, with a new fuel pump that had lasted about a month. In addition to doing only what he had to to get barely adequate clearance for his arm/s, the 'mechanic' either elected not to install a sock or left it poorly attached; there was none when I took out the unit. I've never scrimped on moving whatever might be in the way, rather than overflexing something or trying to sneak around it and causing needless trouble. In the Camaro's case, I unbolted every tubing clip inside the frame so the fuel line merely bowed while the tank gave me plenty of clearance for the sender without coming completely out of the car.

Admittedly, though, it was a bit of a pain.....

I weighted and submerged the Impala's float for a week and it lives up to its name; now, back to either making or salvaging an insulator for the gauge wire's boot to snap on (Wish I'd left it alone).

[GSGregg]

52 Days---progress report:

Found a strainer that would adapt; Airtex FS199 (many American- or Canadian-made Explorers and Mountaineers, '97 to '02) which pushes onto a 7/16" or 11mm nipple and has the same basic offset rectangular shape as what was there originally. I took up the difference between it and the 3/8" tube by cutting a 'ring' off of a vinyl vacuum cap and using it for a grommet. Good firm fit.

The insulator for the terminal is a rubber foot from a defunct guitar effects pedal, shaved down with a bench grinder. Not quite perfectly shaped, but pliable enough, still, to fit well with the boot.

The sender-to-tank gasket is apparently different from the one used with float-arm units (what's the point in that?) so I got a #339 O-ring, 3/16" around 3-1/4" (3-5/8" O.D.). A #338 will also fit (1/8" smaller diameter), as the trough in the tank flange is wide enough.

Tomorrow, hopefully, the tank goes back in and we'll see what does what.....

[Blue Bowtie]

GS,

Be very careful about substitutions of material in the unit. A rubber mounting foot is most likely natural rubber or Buna/nitrile rubber compound. Rubber used in fuel exposure applications is most commonly FKM/Viton. Even EPDM will not resist fuel in the long term. It would be critical to identify the material, and if the material cannot be verified, reject it.

I'm just trying to save you some future frustration after performing all the work to repair the unit.

[Blue Bowtie]

Originally Posted by j cAT

Pictures show the rust not good , because of the alcohol ... bad for carb..I would put a bigger filter in line to the carb .

I hesitate to take exception, but in the interest of reality I cannot avoid it.

Rust in fuel tanks has been happening since 1902. I find it very difficult to place blame upon the often maligned and just as often misunderstood effects of ethanol fuel.

Water has ALWAYS been present in fuel, and has always caused problems, some small and some larger. I will guess that as many of these people who do not understand ethanol fuel additives are the SAME people who have happily poured products like HEET in their tanks to combat the effects of water. Guess what the prime ingredient of HEET is... Go ahead, you get three tries, and I'll wait while you look it up on Google.

Further, my early experience with this was in a 1967 Firebird which I drove for almost 15 years. It had a Rochester 2GC carb. Living in the midwest, we started using ethanol fuel blends as early as 1976. The ONLY problem I had as a result of using ethanol was the sediment cleaned out of the tank by the ethanol. It cleaned the tank well enough to plug the sintered bronze filter in the Rochester (remember those?) and starved the carb. After replacing that filter and adding a much larger transparent plastic inline filter upstream of the carb (and changing it frequently) I had ZERO other issues. The float never dissolved as some people have said it would, the fuel pump diaphragm never melted as some people said it would, the accelerator pump cup never deteriorated as was predicted by these "experts" and the rubber fuel lines never turned to mush.

As j cat advises, when you resolve the issue with the sending unit you might want to consider an external filter, even if the tank has been flushed out as part of this process.

[GSGregg]

Hello, Blue Bowtie; thanks for tuning in!

Regarding substitutions, the rubber pseudo-insulator rests on the exterior surface of the sender flange, and seals against a fabric-reinforced washer (of an appropriate material, as evidenced by its almost fifty years of service) contoured to fill, from the inside, the depth of the hole in the flange metal. As it's unlikely that fuel do more than occasionally splash up to it, I think I'm in good shape.

The vinyl grommet is from the typical vacuum / fuel line cap that Help sells in assortments, and I don't recall any of them dissolving or swelling when exposed to gasoline; on the contrary, they tend to shrink and stiffen with a little age on them, so again I think I'm OK.

The O-ring / gasket is Viton. The only supplier I knew of was MSC Industrial Supply (although Grainger probably has them, too, come to think of it), and it was buy either a 20-pack of Buna-N or a 5-pack of Viton, so I went with the material that's proven itself in carb needles for quite a while.
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My main complaint with ethanol is the disparity between energy contents of eth and gas as mentioned by zFacts in this article:

http://zfacts.com/p/436.html

I thought I recalled numbers like 144,000 and 80 or 85,000, but things blur when you get old.....whatever; my Gran Sport used to get 11-13 mpg combined and 15-16 highway, but after the 3-year downtime I mentioned in the first post, it's been lucky to hit 9 mpg! Same carb, cam, state of tune (actually, the high-octane aspect of ethanol allowed me to restore stock ignition timing that I started retarding years ago) and loose nut (me)---that leaves inferior fuel.

As far as rubber components being damaged, I had a neighbor who stayed on top of things ethanol because he flew a Cessna 180 and didn't like the government's meddling with what we could and could not buy. I can't say I've seen any of that with cars, but chances are that my maintenance / update habits moved old stuff before it would have been affected, anyway.
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One of the first things I did, even before deciding to troubleshoot the Impala's fuel gauge, was install a filter in the line to the fuel pump because I didn't know what was going to come out after 13 years.....

Did you have any luck backflushing the Firebird's bronze filter with aerosol carb spray? It seemed to work for me on my '52 Chevy.

[Blue Bowtie]

Fortunately, the sintered bronze filter elements are still available, or at least were at that time. That was many years ago, but since then I've used everything from E-10, e-22, and E85 without issues.

With a metallic sleeve in the material it may be just fine. I just wanted to bring it up in case. I'm looking forward to photos of the finished project. The '67 Impala fastback hardtop 2-door was one of my favorite bodies ever. I recently restored an instrument cluster for a friend who is restoring the rest of the vehicle.