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54 caddy fuel pump

Started by bigbry13, November 06, 2021, 02:57:14 PM

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bigbry13

Hi all
Would love to get some input. Recently acquired a 54 Cadillac. Car Had been mostly restored but used sparingly and sat most of the time. Was running when I get it, engine had been rebuilt but the carb was definitely out of wack. Took it off, had a friend rebuild the carb and all was good until it wasn't. Took it back off a second time and had and had my mechanic go through it again. He got it running noticeable better and pretty well dialed in. 2 days later I go to start the car and just cranks but won't catch. A few shot of starting fluid down the carb and it will kick over for a second but die. I'm assuming it's the fuel pump that's failed? Anything else to check or anyway to test the pump while
It's still on the car to see if it's the culprit? For what it's worth about 2 weeks ago me and my friend were driving the car after he rebuilt it and it died. We disconnected the fuel line going from the pump to the carburetor and it was pumping gas so it seemed to be ok then. Not getting any fuel into the carb now though when the gas is pressed. The tank was replaced in 2014. There is a clear inline filter under the car which doesn't look to have any debris in it and up until a few days ago there was a glass bowl fuel filter also near the carb that looked clean also. Is it likely the pump is my culprit?
Sorry for the long winded post. Any help would be greatly appreciated.

Also, who makes the best fuel pump available? I was going to have Arthur Gould rebuilders do it but they're 4 weeks out and I need one right away if possible
Bryan

James Landi

Bryan,

If you're familiar with where the fuel pump is located with reference to the just how its mechanism is expected to be oiled, you've likely realized there's a challenge.   The pivot for the pump arm does not receive much lubrication, if any at all, save perhaps, when you add oil to your crank case.  I owned two SDV 56's and they were daily drivers throughout the mid-60 and mid 70's.  I spent a lot of time  mulling over just why my car(s) were starving for gas--- seems that many old time mechanics packed the pump housing with heavy gear grease to keep the pivot lubed and to insure that the diaphragm pump arm did not develop sloppy wear that would negatively affect the operation of the pump.   Oh yes, you can take the pump off the engine and you'll likely find that there is wear at the pivot, and that's keeping the pump from developing the necessary vacuum to pull the fuel, especially during hot days.

wheikkila

I would also check the hoses from the tank to the pump. You could have a crack it the hose and it will suck in air.
             Thanks Wayne

Michael Petti

Get a gauge and check the fuel pressure coming out of the pump. I think it should be 5 or 6 pounds of pressure. I had a 60 CDV Airtex pump that pumped fuel and ran car part of time but stalled and died a lot. I found  that the pump only developed 3.5 lbs of pressure. On hot days it was terrible. I continued to use it while Arthur Gould rebuilt an original AC core for me. Fuel problems much better now with rebuilt pump.

Lexi

#4
This has come up before and perhaps do a search of this Forum for my comments on the 1954 - 1956 Cadillac fuel pump "strainer nut" and tests you can do, (especially with a vacuum gauge & volume tests). The strainer nut is the large nut on top of the fuel pump, (7/8 inch I believe). If that is loose or ill seated with a faulty gasket, your fuel pump will begin sucking in air at that location. You won't see a fuel leak, but it is a vacuum leak which impacts what amount of fuel gets to your carburetor and can cause the problems you described. Believe such is even noted in the Shop Manual/s for this era. I ran into it and could only start car with gas or quick start down the carb's throat, then OK. But got progressively worse. It is a question of degree of gasket not seating properly in which these conditions manifest. Car can also suddenly die. This is a common problem and I have even had new fuel pumps out of the box with a crappy strainer nut gasket, which resulted in an immediate vacuum leak after installation. So this is one more thing you should look at and eliminate if possible. Also, perhaps check out on this Forum posts that describe tips on staking the pump valves which are also another source of problems, I have been told. Clay/Lexi

Edit: You can also check the fuel pump push rod length specs, which I believe are stated in the shop manual

Omarine

I gave up trying to get 2 rebuilt fuel pumps to work on my 52. Im sure the rod is worn because it's not getting enough throw to operate the pump.

The other test you should do besides the PSI test is the volume test. Disconnect your coil from the distributor. Then put the line that leaves the pump into a water bottle. Have someone crank the engine over. You should get nice fuel amounts into the bottle with a few turns of the engine.

Now. In order to solve these problems forever, get an electric fuel pump and mount it to the chassis in front of the rear tire. Route your fuel line away from filler neck and wter pump thermostat housing. You will never deal with this issue again. Mine is 6 volts and i drive it in Florida on the hottest days of the summer. No more fuel delivery issues.

Cheers
Oscar

1949 Harley Davidson FL
1952 Cadillac Coupe de Ville
1961 Chevy Impala 2 dr hardtop

Jeff Rosansky CLC #28373

You can also take the screw out of the side of the bowl to see if there is fuel in it. I did an electric as stated above. Works well.

Jeff R
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille