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Please help - ‘55 sedan stalls at stop, then hard to start - PROBLEM SOLVED

Started by caddychap, May 16, 2019, 08:07:41 PM

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caddychap

Hi everyone - my 1955 sedan has always run great, but it’s recently developed a problem that I just can’t figure out. I tried to fix the problem by installing a new fuel pump and fuel filter bowl, as well as a new gasket between the carb and intake manifold, but no dice. The problem is this - when I stop the car at a light or stop sign, it stalls due to the idle being too low (yes, I need to adjust the idle speed). It will then start up again no problem, at least for the first few times. After several stops and several stalls, the engine just won’t start up again. If I wait for about 5 minutes, it will start again. But 5 minutes is a long time when you’re stalled at a traffic light and there are a bunch of cars beeping behind you.

Does this sound like a carburetor problem? Or could it be that the fuel line in the gas tank gets clogged up after crud gets stirred up in the gas tank? Or something else? Any suggestions are greatly appreciated!

James Landi

When our Cadillacs get hot, they tend to be hard starting, especially if they stall.  We've discussed at length the seasonal gasoline mixes (i.e. winter/ summer blend), the use of ethanol, etc.  I have found that adding Marvel Mystery Oil (about twice the recommended dosage) to the gas tank, helps immensely. I have NO idea why it works, but it does. No more sustained cranking, no more guessing about what to do with the accelerator peddle.  On the 1956 engines (not certain about model years before or after) with the fuel pump mounted on the oil tube, those pumps require that the pump's actuator arm enclosure is to be packed with grease as there is no consistent lubrication that gets up into the lever pivot bearing.  The original fuel pumps had zerk grease fittings on the pump body.  Without the grease, the pump will lose its ability to work successfully.   Hope this helps to generate other ideas,   James   

Caddy Wizard

#2
This is classic behavior for a 55 with modern fuels.  The engine is leaning out when it gets warm, which causes the engine to run hotter, which causes it to run leaner, etc.  Eventually it won't run.  Once the engine and fuel lines cool down a bit, it will run again.  Having driven old Cadillacs as daily transportation a lot over the last 25 years, here are my suggestions:


1.  Only use ethanol-free fuel.  Not every gas station has it, so seek out the ones that do.  But only use this.  Oh, and regular is fine (hi-test doesn't improve your situation at all).

2.  Make sure that the ignition timing is correct!  If the timing is off, the engine can run hotter, leading to this vapor lock problem.  Especially make sure that the vacuum advance unit is in good working order.

3.  Make sure that the cooling system is working to perfection.  Boil out and rod the radiator, if need be.

4.  Better to run slightly rich (which runs cooler) than slightly lean (which runs hotter).  So one can enrich the mixture a tad (not much, just a little).

5.  Best fool-proof prevention is a robust pusher fuel pump (not just an auxiliary pump) that pumps a steady 5psi all the time.  Situate it back by the tank and remove the rod from under the mechanical pump (which now will just be for looks).  This is the single best thing I ever found to solve lean-out vapor lock once and for all.  Edelbrock makes a good pump with a built-in regulator -- costs more than $200. It comes pre-set to 6.5psi, but can be adjusted down to our needs.  https://www.edelbrock.com/quiet-flo-in-line-red-electric-fuel-pump-120-gph-182051.html



Good luck...
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

caddychap

Thank you both for the input and suggestions.  I will check the timing and tweak the fuel mixture. I just had the vacuum advance rebuilt so that’s not an issue. I’ll report my results. Thanks agaim’

walt chomosh #23510

Jon,
  I had a throttle plate worn on my 55CDV. I actually went a few years between instances when it showed itself. (one tends to lose confidence in their vintage Cadillac when he has a mystery problem. I have a Rochester 4GC on mine and even have a spare that has been overhauled and road tested before going into storage. Feel free to contact me should you want to eliminate your carb as the problem.(I'll loan you my spare)...walt...tulsa,ok

Jeff Rosansky CLC #28373

I have an Airtex fuel pump as my only pump. Run it with a relay. The pressure was a bit too hi so I have an adjustable regulator after the pump to spin it down a bit. We have been in traffic on a 98 degree day with no vapor lock problems. We run premium fuel that has the ethanol in it and some Marvels.
With that being said it does idle a bit rougher when hot. It is mid-upper 80's today and it didn't idle great but not bad enough that I would be worried about it.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

phildeville@cox.net

I just finished installing FI Tech fuel injection on the '54.  Although I only have 125 miles on her, it is incredible.  500+ miles are required for " self-learning" feature to prevail.
I probably wouldn't have tried this route....but my brother, Ron, retired GM electrical engineer, has the patience to deal with the data logger & software mods. I did the bracketry & plumbing.
Yes, it took relocating the coil, several program modifications and solving the riddle of EMI....
Starts instantly & idles smooth. Passed urban & freeway test.
Phil
Phil Terry  CLC# 15270

caddychap

Thanks everyone for your input - I really appreciate it. The simple fix was this: I had the carburetor rebuilt. It runs beautifully again and there are no stalling or hard start problems. And the idle is sooo smooth. A huge shoutout to Custom Rebuilt Carburetors in Middlesex, NJ. Phil and his guys did a beautiful job and they have a flow machine that they use to set the air mix when the rebuild is done. So all I had to do was bolt it on. Here are some pics of when I got it back.

Bob Kielar

Congrats looks great thanks for posting the root cause.

Keep Cruzin,

Bob Kielar
Keep Cruzin
1955 Cadillac Fleetwood

Scot Minesinger

Awesome!

It has been my experience that this "bad fuel, ethanol gas, and the like" are really not the issue.  I run my 1970 DVC with stock fuel pump and stock carb with no issues.  The carb has been rebuilt with ethanol proof soft parts, the fuel pump is relatively new, the fuel filter is replaced regularly, the sender is replaced (with sock of course), the tank has been reconditioned, and all the fuel lines, steel along with rubber have been replaced.  Nothing is much older than ten years now and nothing has much more than 35k miles on it.  My Cadillac idles the smoothest when it is hot.  I do suffer the hard to start after a week, or the heat soak on a hot day from about 15 minutes to 120 minutes after shut-off when hot. 

I'm going thru it now to get ready for my drive to GN in KY next week.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

chrisntam

Quote from: Scot Minesinger on June 09, 2019, 02:16:11 PM

I'm going thru it now to get ready for my drive to GN in KY next week.

Make sure your weatherstripping is good, Just arrived in Louisville, it's a frog-strangler (rain) right now!
1970 Deville Convertible 
Dallas, Texas

Caddy Wizard

Quote from: phildeville@cox.net on May 24, 2019, 05:47:12 PM
I just finished installing FI Tech fuel injection on the '54.  Although I only have 125 miles on her, it is incredible.  500+ miles are required for " self-learning" feature to prevail.
I probably wouldn't have tried this route....but my brother, Ron, retired GM electrical engineer, has the patience to deal with the data logger & software mods. I did the bracketry & plumbing.
Yes, it took relocating the coil, several program modifications and solving the riddle of EMI....
Starts instantly & idles smooth. Passed urban & freeway test.
Phil


Cool!  I am doing the same on my 55 FW.  I have all the parts, but have been sidetracked on other tasks of late.  I hope to finish the FI conversion this fall...
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Series75

Absolutely agree with Jon, Custom Rebuilt Carbs in Middlesex are true experts.   When they say "it's all set up, just bolt it on and go" they mean it.   I had the 62, the 66 AIR carb and my 71 Formula Firebird carb done by them, fast reasonable and honest.   Tom #6866

55 cadi

Glad that fixed it, I was having the exact same issue with my 55, I had the carb rebuilt and it hasn't happened since.
1955 Cadillac sedan series 62
1966 mustang convertible w/pony PAC, now in Sweden
2005 Cadillac deville