Author Topic: Fuel issue in my 54  (Read 761 times)

Offline RobertM

Fuel issue in my 54
« on: January 04, 2018, 12:56:36 PM »
Every time I start my 54 after its been sitting unstarted for a couple days or more, I have to crank the ignition for at least a minute or so to get fuel to the engine.

It seems it's all running back to the tank and I have to draw it anew every time. Any guesses on where I should start to look to solve this? I already killed one battery because of it and I'm worried I'm damaging other things.
Bob Melms
'54 60S
'99 Eldorado

Offline novetti

Re: Fuel issue in my 54
« Reply #1 on: January 04, 2018, 06:40:15 PM »
You might have a leak in your carb which is draining the carb bowl completely after been switched off. I would check that first (power valve in the carb ?).

Also look for any leaks in the whole system (from tank to carb). Check all connections, pump, fuel filter etc.

Offline Chris_Oz

  • 61-62 Cadillacs Owners Group
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Re: Fuel issue in my 54
« Reply #2 on: January 04, 2018, 08:09:27 PM »

A few thing can cause this issue.

Modern fuels have a much lower boiling point then fuel from 1955, so heat soak, from even normal engine temperatures can cause fuel to "boil off" after parking.

The carbs on these old girls are also vented to atmosphere, allowing the fuel to evaporate, again at a pretty fast rate, half fill a coffee cup and leave it on your garage bench, watch how fast it disappears.

Fuel pump, which I think may be your biggest issue.
They have a check valve in them that stops the fuel from flowing back to tank, this keeps the pump "primed" to allow fast pick-up from tank in a few winds of the engine.
If the check valve is not sealing fully, the pump will still work, but will be pulling from a near empty line each time, empty fuel pumps don't like to prime.

The fuel pump may not be leaking externally, it will just allow the fuel to flow back slowly to tank.

Our 1962 CDV had the same issue, the pump worked fine, it just allowed fuel to flow back after 2 days causing a long cranking time.

I fitted a small inline check valve before the fuel pump, down out of site, it now starts straight away every time.
I have just finished getting the bumpers re-chromed, the car was parked for 8 weeks without starting, second wind over had the filter full, third wind had it cough to life.
« Last Edit: January 04, 2018, 08:16:02 PM by Chris_Oz »
Current Cadillac's
1962 Park Avenue Sedan deVille
1962 6 Window Sedan deVille
1962 Coupe deVille

Offline South_paw

Re: Fuel issue in my 54
« Reply #3 on: January 04, 2018, 08:55:13 PM »
Leaky carb. My fleetwood was similar to your start situation. Rebuilt the carb and the problem was solved.

1956 Eldorado Biarritz
CLC Member since 2001 (Unlisted in Directory)

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Offline PHIL WHYTE CLC 14192

Re: Fuel issue in my 54
« Reply #4 on: January 05, 2018, 03:41:58 AM »
I would say the same as Lou, the carb is emptying either through leaks or evaporation. What concerns me though is your battery dying. I have had a problem with my 54 killing batteries and it was the voltage regulator that was the problem - it was not regulating the voltage so it over charged and boiled the battery and it was not cutting out when the engine was off so there was a constant drain on the battery. Cranking it over should not do the battery any harm. Phil

Offline Lexi

Re: Fuel issue in my 54
« Reply #5 on: January 05, 2018, 10:57:54 AM »
Happy New Year to all. Hi Phil, I had the same thing happen to my '56, with the problem eventually getting to the point where I had to prime the carb to start it after it sat for a day or two, (by pouring gas down the carb throat). I also had carb issues (went through 5 Rochesters and/or parts thereof to fix). I also had a leaky fuel line at the gas tank as well as an air leak in my new fuel pump, (think '54 & '56 are the same). That leak may be another possible explanation for your problem. I found that the large nut on top of the pump was no longer seated air tight and was admitting air while the pump was in operation. Crazy thing was, NO fuel leaked out, just AIR leaked into the system, so there never was any external sign of a problem. Vacuum and volume tests would reveal this problem. I removed the so-called strainer nut and wrapped the threads with gas fitters tape and also replaced the steel washer with a combination viton/metal transmission washer part. Problem fixed. I did a post on the CLC Forum; top of page 2 of that thread has my notes on tests and strainer nut issues. I also had a post on page 1 of this thread where I discussed the strainer nut in greater detail. There are other useful comments there as well as posted by many of the "Cadillac Gods" who also wished to assist on these matters. Clay/Lexi
« Last Edit: January 05, 2018, 11:31:38 AM by Lexi »

Offline PHIL WHYTE CLC 14192

Re: Fuel issue in my 54
« Reply #6 on: January 05, 2018, 11:11:24 AM »
Hi Lexi, That's interesting about that large nut on top of the fuel pump, as mine on my repro [Airtex] fuel pump leaked there. My main problem though was the split flexible fuel line to the pump, I had a new one made and all was good ! Phil

Offline Lexi

Re: Fuel issue in my 54
« Reply #7 on: January 05, 2018, 11:14:18 AM »
Great to hear! Sounds like you now may be entering the hallowed halls of the "Cadillac Gods" as well! Clay/Lexi

Offline RobertM

Re: Fuel issue in my 54
« Reply #8 on: January 05, 2018, 11:22:17 AM »
All good stuff!

I have a sneaking suspicion it's the fuel pump, only because I can't recall if I had this problem when I had a new fuel pump installed. The replies here reminded me I took the new one off a couple years ago to paint, and put the original (rebuilt) fuel pump back on. I had completely forgotten I never swapped it back.  That will be my first step. Will take a while, tho. The car is now in North Carolina and the new fuel pump and I are in Connecticut.

The carburetor was rebuilt in 2013, only about 2000 miles ago.  I'll have the guy that did that rebuild take a look.
« Last Edit: January 05, 2018, 11:35:20 AM by RobertM »
Bob Melms
'54 60S
'99 Eldorado