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Fuel pump for my 68 Coupe deVille...

Started by Steve W, November 21, 2022, 10:14:21 PM

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Steve W

Well...turns out the gas smell wasnt the carb after all! I was able to make some finite adjustments on the air/mix screws. Not fun, but do-able. Got it to 19 on my vacuum gauge (it was around 17 when I started). Car still runs great!(knock on wood!)
But I still smelled a little gas. Looked under the car and, saw a small leak from the vacinity of the rubber fuel lines near the fuel filter and the fuel pump. So I replaced all the rubber lines! Nope...it seems to be leaking from the actual fuel pump itself! (it's around the back side...can't see the actual leak, but I CAN see the dripping! There isn't anything else there that it could be! And the top of the fuel pump is bone dry. In all my years of messing with old cars, I've never had the fuel pump itself leak! Learn something new every day!

So...any advise as to what fuel pumps are the best..or which ones to avoid? I'm running the stock mechanical fuel pump, stock quadrajet, stock 472 engine. I'm going to start a new fuel pump thread as well, just in case.
Steve Waddington
1968 Coupe deVille
North Hollywood, CA
CLC Member # 32866

Michael Petti

If possible, rebuild what you have. I went through 4 new pumps from Carter in 2 years. I finally got an original AC pump; had it rebuilt by Art Gould and have had no problems since then. This site is loaded with post about new fuel pump lack of quality no matter what the brand.

klinebau

There are a few flare fittings that you should check before replacing the pump.  I think for '68, there are hard lines running to and from the fuel filter each connected with a flare fitting.  I would definitely check those first.
1970 Cadillac Deville Convertible
Detroit, MI

fishnjim

I would take it off and inspect it for damage, cracks or thread leaks, as noted above before attempting rebuild.  Sometimes the screws get loose, but the diaphragm is always suspect.  It a coated fabric so can seep out if the coating is compromised.
Failures with new have been mostly around the check valves, I've seen, but frequency was enough to switch from mechanicals.
The threads can be damaged from over tightening.  Use regular pipe dope on them, not teflon tape or teflon paste.  The pump side threads are NPT which are tapered and tend to wedge apart.  They bottom out quickly and the housing metal is soft like the brass and both can strip or be damaged.

35-709

Do not think those pumps are rebuildable.  Probably the best you are going to do is get a new one from NAPA, etc.  Don't recommend searching out an NOS pump, the older diaphragm will likely not be compatible with ethanol laced fuel.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Daryl Chesterman

#5
Mr. Newcombe is correct in post #4.  Your OEM is not rebuildable, and as he said, the NOS will not be compatible with ethanol fuel.  See website below for what an NOS pump looks like—courtesy of Ebay:

     https://www.ebay.com/itm/123748948357?hash=item1cd0031985:g:EeQAAOSw3JxcxN-n&amdata=enc%3AAQAHAAAAsH8IBnWOUc5PPxEXVPfns7NTpG10pSfWu%2FP35CVNTfzAKxZKk3Bm%2BcVR0Pi%2Fo30brzBUg6PRvql3WmMrivrH6ILA4N2JxNcR%2BdeLS4qSdWL35oKwyTo%2BrcYav5inQU60lIbvSGOLaqlR%2BAiupUOUMKTgqBocUlA7Zv9SZLVZWT4RJEo9kbniGhBlWlzhY7GeA4YwE4h8hm97mJQbLBA4WRXHK7A8ffttnHSj8srbYzxr%7Ctkp%3ABk9SR4iG6p6UYQ#readMoreDesc

NAPA shows part number B0153P as the pump fitting your car.  I have had mixed success with the NAPA pumps in that one I received had one of the valves come out of its cavity (after a short period of use) because it was not staked in, another was putting out 9 psi pressure (too much) and flooding the carb.

Rock Auto shows a CARTER M4643.

It is buyer beware as most aftermarket pumps are made offshore!

Edit:  If your old pump is leaking through the diaphragm (probably what is causing your external leak), there is a good possibility that gasoline is leaking into the oil pan.  Pull your dipstick and if it is overfull, or smells like gas you will want to change the oil and filter.

Daryl Chesterman

Steve W

Well...that's a challenge! Carter fuel pumps dont seem to be highly regarded...and NAPA has their fair share of critics too! And, a NOS is just too old to be considered a safe bet! And in looking online, it looks like some of these retailers have the same part, and just re-badge it. And I see the exact same Carter pump M4643 going for anywhere from 23.00 to 42.00! So, I just gave up and ordered the Spectra Premium from Auto Zone. Should be here tomorrow. (Free overnight shipping!) Fingers crossed its the right one, and a good one. And, yes, I'll change the oil immediately after, even though I didn't see anything on the dipstick.
Steve Waddington
1968 Coupe deVille
North Hollywood, CA
CLC Member # 32866

Highwayman68

1968 Fleetwood Purchased in 1981

Michael Petti

A NOS pump would have to properly rebuilt to tolerate today's fuels.