Author Topic: Same old issue discussed many times......but want to ask again.  (Read 946 times)

Offline z3skybolt

  • Posts: 74
    • CLC Member
      CLC Member #30482
  • Name: Robert L. Ritchie
Same old issue discussed many times......but want to ask again.
« on: September 22, 2017, 10:44:19 PM »
For all you pros...

I've seen this issue discussed here before but will ask for any comments once again.  Just installed my newly overhauled 346.  Drove it about 40 miles today working on the break in.

It was a hot day here....93 degrees.  The car would vapor lock every 4 or 5 miles. I'd turn on the electric fuel pump and all would be fine.  When I raised the hood while only running the engine driven pump the fuel would boil,lots of rolling bubbles in the glass bowl on the fuel pump. When I would turn the electric on....the bubbles and boiling stopped.

Before it was overhauled I could drive it 15 to 25 miles at a time, even on hot days just using the engine driven pump.  Every 15/25 miles it would begin to cut out and I would turn on the electric pump momentarily everything would be fine again for several miles then repeat.

The engine driven pump was newly rebuilt about 1,200 mile ago.  It actually never worked much better than the old one.  But I kept it anyway with the old one as a spare backup.

Before it was overhauled I had the fuel line wrapped with insulation tape about 12 inches of line before the fuel pump.  Tomorrow I will wrap it again and see if that helps.  By the way....I am running 87 octane non-ethanol fuel....with a bit of Marvel Magic stuff added.  I've tried 100 low lead aviation gas and everything in between prior to the overhaul. Nothing helped.

I am about ready to just run the electric pump all the time. Hate to do that though. But if I must.

What do you think?

Bob
« Last Edit: September 22, 2017, 10:48:14 PM by z3skybolt »

Offline Steve Passmore

  • Posts: 4835
  • Name: Steve Passmore
Re: Same old issue discussed many times......but want to ask again.
« Reply #1 on: September 23, 2017, 02:28:48 AM »
That may not be boiling in the pump bowl Robert. It's never that hot here and one of my 41s has bubbles in the bowl sometimes. I don't know anything about how your electric pump is connected but could it be the mechanical pump is having trouble pulling fuel through the electric one?  If that were the case the mechanical could be creating a vacuum and pulling air bubbles from any fitting it could find, then just run out of fuel.    Just a thought.
Steve

Offline z3skybolt

  • Posts: 74
    • CLC Member
      CLC Member #30482
  • Name: Robert L. Ritchie
Re: Same old issue discussed many times......but want to ask again.
« Reply #2 on: September 23, 2017, 01:12:38 PM »
Steve,

Thanks.  I have considered the possibility that the mechanical was sucking air from somewhere.  Makes sense as the bubbling stops when the electric is turned on.

However after driving with the mechanical pump on it will sit and bubble at a decreasing rate for as long as one hour. That is why this novice thought it was boiling.  One would think the air bubbles would have dissipated far quicker.  Of course you know that it sits real close to the left head of the engine. Lots of heat there.

Will keep troubleshooting.

Thank you again,

bob

Offline Steve Passmore

  • Posts: 4835
  • Name: Steve Passmore
Re: Same old issue discussed many times......but want to ask again.
« Reply #3 on: September 23, 2017, 01:34:04 PM »
If possible I would remove the electric pump and see if you have the same symptoms.
Steve

Offline 55 cadi

  • Posts: 515
  • Near Dallas, TX
  • Name: J Oliver
Re: Same old issue discussed many times......but want to ask again.
« Reply #4 on: September 23, 2017, 01:55:21 PM »
I would also go over ALL fuel line, tighten every clamp and fitting again, even the slightest can allow air in and won't see gas come out while running.
Jason
1955 Cadillac sedan series 62
1966 mustang convertible w/pony PAC, now in Sweden

Offline Jason Edge

  • Posts: 669
    • CLC Member
      CLC Member #14225
  • Name: Jason Edge
Re: Same old issue discussed many times......but want to ask again.
« Reply #5 on: September 23, 2017, 02:35:49 PM »
I would ditch the electric pump... period. They are more trouble than they are worth. I have been using a standard mechanical pump on my 64 Cadillac for 20+ years with zero issues. We have dozens of days here in North Carolina in the 90's and usually a few in the 100's and humidity that makes AZ heat seam like a cool spring day, and no problems.  I am into upgrades where they actually work (e.g. Pertronix II Ignition), but unless you have an 850 dual line double pumper sitting on top a high rise intake, and running down the 1/4 mile at the strip every Saturday, I would stick with the stock setup.  I ran my car for probably 10 years with the stock Carter AFB, and then with the Edelbrock Peformer 750 cfm with a modified intake to take advantage of the larger front carb primaries, and the stock fuel pump works fine and keeps gas full in the glass fuel filter bowl. I used a stock fuel pump for first 15 years on an engine with 155K to 160K miles, and then again through break in back after rebuild in summer 2012, and since put several thousand miles on the engine in cold to hod weather with zero issues or need for an electric fuel pump.  I can flat out punch the big 750 at any speed and am never deprived of fuel. That's my 1/2 cent!
« Last Edit: September 23, 2017, 03:43:23 PM by Jason Edge »
Jason Edge
Director CLC 1963-1964 Cadillac Chapter - www.6364Cadillac.com
VP CLC Eastern NC Region - www.clcnceasternregion.com
email - jasonedge@nc.rr.com
1964 Coupe DeVille - http://bit.ly/1WnOQRX
2002 Escalade EXT
2012 SRX Performance Edition

Online Jeff Rose CLC #28373

  • Posts: 1370
  • Name: Jeff Rose
Re: Same old issue discussed many times......but want to ask again.
« Reply #6 on: September 23, 2017, 02:36:30 PM »
I would expect a new engine to run hotter while breaking in.
Jeff
Jeff
CLC #28373
1970 Coupe DeVille
1955 Series 62

Offline James Landi

  • Posts: 628
  • 2007 XLR
    • CLC Member
      CLC Member #21920
  • Name: James Landi
Re: Same old issue discussed many times......but want to ask again.
« Reply #7 on: September 23, 2017, 06:11:13 PM »
To put a finer point on some of the observations, if the car is hesitating and on the point of stalling, and using the electric fuel pump overcomes that problem while the car is running, you have a leak in the fuel line somewhere, as suggested above.   You may need to get the car on lift, or you may spy some drops of fuel under the car.  Often, after many years, the metal fuel lines develop pin holes from road salts, and unless you're running the car in neutral in one parking spot and then carefully looking for a small puddle of gasoline, you'll not detect the leak.  On some of our old Cadillacs, there are old. cracked rubber gas hoses on the very top of the tanks that are hard to reach--- you may have a leak in a feed hose that is causing your onboard pump to draw air and your electric pump to overwhelm the hole with sufficient vacuum.  THe boiling of fuel occurs after the car is sitting hot, with the engine off.  Using Marvel Mystery oil has helped me with my older Cadillacs that are hard to start when they are in hot weather after a short stop.  I've experimented with larger qualities of Marvel, and found that using around a measured cup and a half per full tank truly eliminated the hard summer start ups on some of my cranky Cadillacs.

Offline 59-in-pieces

  • Posts: 721
    • CLC Member
      CLC Member #17326
  • Name: S. Butcher
Re: Same old issue discussed many times......but want to ask again.
« Reply #8 on: September 23, 2017, 09:08:47 PM »
Bob,
I too have read many posts about vapor lock and how to avoid it - what with the new alcohol additives or not - all while getting ready to restore my 47 Series 62 convertible.

I found comments by Bill Ingler most persuasive (after all, admittedly my guru for the 47) - in that some electric pumps actually inhibit the flow of fuel when not turned off, and seem to cure the problems when turned on. 

I would hope Bill might jump in, but failing that, I suggest you review some of his posted insights.

I agree with the others who have pointed to cracks-splits in seemingly solid fuel lines, and crack in the hoses, clamps - particularly leaving the fuel tank - gr8 suggestion there.
I would also pressure test the lines with air and a gauge ( with soap works gr8) - with both ends closed off - or vacuum works as well (no soap) - to see if either measure reveals a leak - falling gauge measurements).

Have fun,
Steve B.
S. Butcher

Offline Brad Ipsen CLC #737

  • Posts: 749
    • CLC Member
      CLC Member #737
Re: Same old issue discussed many times......but want to ask again.
« Reply #9 on: September 23, 2017, 09:32:24 PM »
Also make sure you don't have winter gas in the car.  Much higher vapor pressure.
Brad Ipsen
1940 Cadillac 60S
1938 Cadillac 9039
1940 Cadillac 6267
1940 LaSalle 5227
1949 Cadillac 6237X

Offline The Tassie Devil(le)

  • Administrator
  • Posts: 7296
    • CLC Member
      CLC Member #18992
  • Name: Bruce Reynolds
Re: Same old issue discussed many times......but want to ask again.
« Reply #10 on: September 23, 2017, 09:43:50 PM »
I cannot see how having an Electric Pump will hurt, or having a mechanical pump, but it is virtually pointless to have both.   I can see the use for a prime pump for the less-used vehicles to save the starter motor, but these should be separate from the mechanical system.   The original was never designed to overcome the restrictions to pull through another pump.

If one is going for originality, then the mechanical one is the go, but with these modern-day fuels that seem to be causing problems, Electric is the way to go.   BUT, everything else in the system has to be modified to be compatible with the new fuels.

I have run electric pumps in cars, and original mechanical ones as well, and each has performed flawlessly, apart for some vapour lock with the mechanical, and once with the electric when it was placed up at the engine, and not back at the tank.   (Wasn't me that placed it in the engine bay)

The factory systems are perfect for basic use, and some performance, but, as I said before, fuels these days are different.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
(Past President Modified Chapter)

Offline 76eldo

  • Posts: 4931
    • CLC Member
      CLC Member #22443
  • Name: Brian Rachlin
Re: Same old issue discussed many times......but want to ask again.
« Reply #11 on: September 24, 2017, 07:42:58 AM »
I had a similar issue years ago with a fully restored 36 Packard with a new engine.
I had no problems with hot starts but the car did run hot in summer weather and on occasion I experienced vapor lock.

I installed an electric pump down on the frame towards the tank.  I used it to pressurize the line when the car hadn't been run in a few weeks to avoid excessive cranking while starting it. It worked great for that.  There were times when I was driving the car in the summer heat and it started to run poorly at low speeds when the temp gauge was getting in the upper range. Turning on the pump solved the problem immediately.

I think the optimal way to install an electric pump and still use the mechanical pump would be to install a T fitting in the line at the electric pump. Run a second line and another T fitting before the mechanical pump. This will allow the fuel to draw directly from the tank for the mechanical pump and create a parallel path for the electric pump to push more fuel when needed. So the two pumps will not be in series but in parallel.

Brian
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443

I prefer email's not PM's   rachlin@comcast.net

1960 62 Series convert with factory Tri Power
1960 Eldorado Seville
1970 DeVille convert
1976 Eldorado convert
1980 Eldorado Hess & Eisrnhardt convert
1981 Eldorado Hess & Eisenhardt convert
1985 Eldorado Biarritz convertible
2007 DTS
2012 CTS Coupe
2017 CT5

Offline C Gorgas

  • Posts: 83
    • CLC Member
      CLC Member #25441
Re: Same old issue discussed many times......but want to ask again.
« Reply #12 on: September 24, 2017, 08:16:59 AM »
I think Steve has a good point. Is the pump for dual purpose? Is it designed for priming and full time or just full time? That might be an issue. Not sure what that has to do with anything but a thought. Chet 25441

Offline Dave Burke

  • Posts: 173
  • Name: D. Burke
Re: Same old issue discussed many times......but want to ask again.
« Reply #13 on: September 24, 2017, 10:04:27 AM »
Hi Guys,

I run both a mechanical and an electric in my '57 Series 62.  They share a common line, but I split the main line at the tank and added a secondary loop for the electrical pump with a check valve that keeps the fuel from backing up into the tank when I use the electrical pump.  I have noticed no problems with fuel delivery when I hit the electric pump.  I did the same on my '63 Series 62 as well, but I put the electric pump a bit further forward.  As far as the dreaded vapor lock goes, and fuel bubbling in the glass bowl, I too have posted questions about this many times.  I think that the biggest problem can be spelled out in three letters: TEL, or the lack of it.  Additives help, but even here in Alabama my old girl will throw a fit on warm days, especially in traffic!  And there is nothing worse than stalling out in a major intersection because of fuel starvation!

Good Luck!

DBurke
CLC  27968 (The check is in the mail!)
1957 Sedan Deville
1963 Series 62 - Project LUX

"Who loves ya, Baby?" - Kojak

Offline gary griffin

  • Posts: 1996
  • garygriffin@Q.com
    • CLC Member
      CLC Member #26430
  • Name: Gary Griffin
Re: Same old issue discussed many times......but want to ask again.
« Reply #14 on: September 24, 2017, 11:08:58 AM »
The point where a liquid will become a gas is a variable depending on pressure and temperature. An example is that in out older cars a valve in the carburetor opens and exposes the fuel to lower pressures and it evaporates (Flashes) into a flammable gas.  The bubbles you see in your fuel pump are gasoline being vaporized by the lowered pressure.

The two ways to eliminate vapor lock are to increase pressure in system or lower the temperature, or a combination of the two.   

Drawing the fuel with a pump near the engine increases the possibility of vapor lock as the pump is sucking the liquid, lowering the pressure there lowering the "Flash Point"

Pressurizing the system with a pump near the tank will solve the problem.

As an aside my Lincoln town car has a fuel pump inside the tank. My cousin who has same car just had a new fuel pump installed and the tank was full. The shop lowered the tank to replace the pump (About an $800 job).   I would have created a door in the floor of the trunk myself.
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline Bill Ingler #7799

  • Posts: 1493
    • CLC Member
      CLC Member #7799
Re: Same old issue discussed many times......but want to ask again.
« Reply #15 on: September 24, 2017, 11:24:54 AM »
Bob; Not much more to add that hasn`t been already posted. Back in the 80s I used a pulse type pump made by Walbro or A/C. which allowed fuel to flow through the pump with little restriction to the engine pump. Along comes today`s fuels which destroyed the rubber diaphragm of the pulse pump so they stopped make this type pump. I switched over to a Carter vain type pump but this vain type pump restricted flow to the engine pump.  Thanks to Buck Varnon in Michigan,I followed his design and used a one way check valve plus a by-pass line, which although is complicated to build, has worked well for me.See picture below. Today if I were to choose a pump it would be a Airtex pump.  Bill 
« Last Edit: September 24, 2017, 11:26:59 AM by Bill Ingler #7799 »

Offline z3skybolt

  • Posts: 74
    • CLC Member
      CLC Member #30482
  • Name: Robert L. Ritchie
Re: Same old issue discussed many times......but want to ask again.
« Reply #16 on: September 24, 2017, 12:32:11 PM »
Thanks to everyone,

My electric is an Airtex.  The design of the Airtex appeared to allow a clear flow path for the mechanical pump when the Airtex was turned off. I had hoped to use it only as a back up with the mechanical as primary.  Before the engine overhaul that worked reasonably well.  Since reinstalling the engine 140 miles ago I've had the experience of constant fuel interuption when operating only the mechanical.

Perhaps when the engine was reinstalled and all lines hooked up something was not tightened allowing air to be sucked in. That will be my first attempt at a fix.   All my lines are new stainless steel only a couple of years old, installed when the new stainless fuel tank was built. All along I considered running a bypass around the electric just to make life easier for the mechanical. If I can find no air leak sources the bypass will be my next action. 

Bob

Offline gary griffin

  • Posts: 1996
  • garygriffin@Q.com
    • CLC Member
      CLC Member #26430
  • Name: Gary Griffin
Re: Same old issue discussed many times......but want to ask again.
« Reply #17 on: September 24, 2017, 04:00:47 PM »
A decent fuel pump will usually solve the problem by bringing the pressure to above the flash point   Insulating the lines near the heating of the engine can help also.  Unfortunately we drive our cars more in the summer and closer in temperatures nearer to the flash point.

Also we do not fill up as often and are likely to have older gas in the tank. Winter gas is formulated to lower the flash point so it we fuel up for a Christmas drive and try to go for a drive  in July we are more likely to have vapor lock!
« Last Edit: September 24, 2017, 04:42:38 PM by gary griffin »
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1942 Cadillac 6719 (parts car) (Gone)
1957 Cadillac 60-special (Needs a little TLC)

Offline Dave Burke

  • Posts: 173
  • Name: D. Burke
Re: Same old issue discussed many times......but want to ask again.
« Reply #18 on: September 26, 2017, 09:33:50 PM »
"Also we do not fill up as often and are likely to have older gas in the tank. Winter gas is formulated to lower the flash point so it we fuel up for a Christmas drive and try to go for a drive  in July we are more likely to have vapor lock!"

Well yeah, but after having that gas in the car for 6 months, I'd worry more about a gummed carb!

I say to heck with the environment: BRING BACK LEADED GASOLINE!

Keep 'em rolling!

Dave Burke
1957 Sedan Deville
1963 Series 62 - Project LUX

"Who loves ya, Baby?" - Kojak

Offline Scot Minesinger

  • Posts: 4209
    • CLC Member
      CLC Member #20543
Re: Same old issue discussed many times......but want to ask again.
« Reply #19 on: September 27, 2017, 06:47:14 PM »
Since you brought up an old issue discussed before, please to contribute my 2 cents.  I agree that a mechanical pump should be fine, and Jason and others wrote why effectively.  You think it did not get hot in the 1940's?  Of course it did and Cadillacs were prized for durability and reliability, a luxury at the time.  Cracked fuel lines and other issues can be mitigated with an electric fuel pump.  I'm against them.  It makes the car such that it can only be driven safely by the person that installed the pump.  Just go with the factory set up.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty