Author Topic: 1957 Cadillac Eldorado Seville Fuel Problem  (Read 212 times)

Offline Seville1957

  • Posts: 115
  • Name: Willie Outlaw
1957 Cadillac Eldorado Seville Fuel Problem
« on: November 29, 2017, 12:39:36 AM »
Hey guys,

I have a 57 Seville with OEM dual quad Carter setup. Car is a pain in the butt to start if it has been sitting for more than a few days, but after several cranking tries gas is pulled up in the carburetors and fires up fine. After two to three days later I notice the glass fuel filter fuel level drops and will eventually run out completely. What in the heck is going on? I've read in other online forms that state this is common and thus why many classic car owners will add an electric fuel pump. Any guidance will be appreciated.

Offline fishnjim

  • Posts: 371
    • CLC Member
      CLC Member #29423
  • Name: J. Bozin
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #1 on: November 29, 2017, 09:51:41 AM »
Just aren't like the modern cars are they?   Now you know what a "classic" is all about...
The fuel pump sucks the fuel up, makes a little pressure, and dumps in the fuel bowls of the carbs on a on/off level system.   When you shut it off and it's still hot, there's still some fuel evaporation.   The ethanol blend fuel has a bigger problem with this.  What's left is higher boiling/harder to ignite.   When the level goes down, the needles open and call for fuel.   So either the fuel which is still under pressure feeds to the carbs, depleting the fuel bowl or when not pumpong, the check valve or diaphragm on the pump is stuck or malfunctioning, the fuel will drain back to the tank or out pump.{or both}
Post war Cad exascerbated this by having the exhaust pass through the manifold under the carb, to prevent what was preceived as "carb icing".   Accumulation of ice from the enthalpy loss of evaporation from atomization of the fuel in the carb.   This might have been a problem on early air cooled aircraft, but not in autos generally, and design was dropped in later years.  {Much like left hand thread lugs, after they understood torque of bolts.}  Some blank off these ports to minimize heat problems.   
About all you can do is check the fuel system and make sure it's functioning and not leaking, blank off the manifold, and use non-ethanol fuel.  Carb isolation spacers might also help.

Offline signart

  • Posts: 187
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #2 on: November 29, 2017, 10:55:33 AM »
Try an inline check valve. About $6-$10.  Worked for me.
Art D. Woody

Offline Jeff Rose CLC #28373

  • Posts: 1434
  • Name: Jeff Rose
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #3 on: November 29, 2017, 12:40:56 PM »
Try an inline check valve. About $6-$10.  Worked for me.

You know, that's a good idea. I mite try that in the 70. Did you put it before or after the pump?
Jeff
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline signart

  • Posts: 187
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #4 on: November 29, 2017, 04:10:46 PM »
On a '70 I would put it between the carb and pump. If the carb stays primed it should start.
Art D. Woody

Offline Dave Shepherd

  • Posts: 1933
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #5 on: November 29, 2017, 04:16:49 PM »
Can we assume both chokes work properly?  Accelerator pumps functioning, I have worked on a few of these cars and both those issues were common problems.

Offline Seville1957

  • Posts: 115
  • Name: Willie Outlaw
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #6 on: November 29, 2017, 06:34:23 PM »
Can we assume both chokes work properly?  Accelerator pumps functioning, I have worked on a few of these cars and both those issues were common problems.

Just rebuilt the fuel pump, pretty sure it works. Now the car runs but carbs are original and need to be rebuilt so I guess I could be losing prime due to the carbs?

Offline Dave Shepherd

  • Posts: 1933
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #7 on: November 29, 2017, 07:32:50 PM »
I mentioned the accelerator pumps, if that circuit is weak, even with fuel in the bowl, it can cause cold start issues.

Offline walt chomosh #23510

  • Posts: 316
    • CLC Member
      CLC Member #23510
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #8 on: November 30, 2017, 08:12:19 AM »
seville1957,
  If I may take a moment to tell you a story about my 1955CDV carb's (Rochester) choke adjustment and motor starts. (makes no difference what year or what type carb....this is not rocket science) I struggled with my cold starts for many years (18 or 19!) and did install an electric pump which I like but had no effect on my start problem. I picked up a correct "spare" carb (Rochester) for my model year and installed it to confirm it was roadworthy should I ever need it for troubleshooting purposes. With the choke plate set at .050(per service manual) cold it was ALSO a bad cold starter. One day, after finally getting time to "play" with my Cadillac (man cannot survive on one toy alone!) I decided to set the choke plate closer to .000 and guess what, the motor then came to life after minimal cranking. Moral to the story, sometimes the service manual (RARELY) must be overridden using common sense. Now if I could just get my 1951 Harley Panhead's (CV carb) cold starts where I'm satisfied...this is getting exhausting.. walt...tulsa,ok

Offline 57 Eldo Seville

  • Posts: 59
    • CLC Member
      CLC Member #28497
  • Name: Dave Morris
Re: 1957 Cadillac Eldorado Seville Fuel Problem
« Reply #9 on: December 01, 2017, 08:03:00 AM »
Hey guys,

I have a 57 Seville with OEM dual quad Carter setup. Car is a pain in the butt to start if it has been sitting for more than a few days, but after several cranking tries gas is pulled up in the carburetors and fires up fine. After two to three days later I notice the glass fuel filter fuel level drops and will eventually run out completely. What in the heck is going on? I've read in other online forms that state this is common and thus why many classic car owners will add an electric fuel pump. Any guidance will be appreciated.

This sounds exactly like my experience with the dual quad Carter setup.  I also had a problem with flooding that was fixed with choke adjustment.  It starts great the next day or two after driving but if it sits for a week or two I just plan on cranking a bit.  The new battery helps a lot.
« Last Edit: December 01, 2017, 08:22:32 AM by 57 Eldo Seville »
Dave Morris
CLC#28497
1957 Eldorado Seville