1928 Fast Four fuel issue

[87TT]

Hi all, new here and to this car. I inherited a 1928 DB Cabriolet Fast Four. It was my father's and he restored it from the ground up. I will post pictures of before and after. Anyway, He passed away two years ago and I decided to keep the car. I took my mother on a Nickle tour with it last year and it had some problems. Turned out it was starving for gas. The vacuum tank was missing when he found the car and he put on an electric pump with a dial regulator. He had the same set up on his 1915 touring and no issues with either. On this car the pump ran but at higher rpms it would not keep up and the float bowl would empty and the car would die. I put a new fuel pump on but then it will over flow the float bowl  at higher rpm for very long. I have tried several pumps and regulators but cannot get the pressure low enough to not start spitting gas. I put a gauge on the output of the regulator and it's saying 2.5 to 3 PSI.

I guess my question is what fuel pump and regulator can I use? Or any other ideas?

 

As found

 

Now

As found

Edited July 9, 2023 by 87TT
grammer (see edit history)

[Minibago]

Welcome TT, you have a great car and nice family history.

Put a working vacuum tank on it and enjoy yourself.

Myers, Romar or one of our fellow enthusiasts will be able to help source one.

 

[87TT]

I thought about putting a tank back on but may be a bit costly even if I could find one. My mom says that my dad disconnected the tanl on his 1915 because it didn't work well in the mountains where he lived/ I live in the foothills And just want to drive it for pleasure. My Dad drove his 1915 from coast to coast in the US without any problems once. His 16 was used in the Dodge commercial for the 2014  Dodge charger. Going to call Myers back next week as he was out when I called last week. My parents were friends with them.

Edited July 10, 2023 by 87TT (see edit history)

[Minibago]

Tom and Cindy Myers are first class folk, ten out of ten from me.

The vacuum tank’s work great but need good vacuum, running up hill in top equals low revs and low vacuum and will cause starvation. Changing down will provide the necessary revs / vacuum but second is very low.

[nat]

       The carburetor needle and seat may be leaking and/or sticking.  New seats with a rubber seal, (replaceable O ring), are available.  Brass seats can be lapped with a slurry of abrasive cleaner such as Ajax or Comet.  Valve lapping compound is too coarse.

     Engine vacuum is highest when the throttle is closed.  The vacuum tank holds 1 quart of fuel so a three mile climb may drain it if the throttle is left wide open.   An occasional momentary release of the throttle will help recharge the fuel supply.

[87TT]

Thanks for the Information nat. The car doesn't have a vacuum tank and hasn't since my Dad "rescued" it. I live right off of HWY 95 in Idaho which is The only North South Highway in the state' Most of it has no shoulder and can be very busy at times with big truck traffic. There are some long steep grades in either direction from here too. So I guess I don't feel comfortable driving the car in second gear on the HWY. at 35 to 40 on the hills would be bad enough. The carburetor has a brass seat and I took it out and it "looks" smooth but I suppose it could be worn. Thing was it never had a problem overflowing until I changed the electric pump that was not pumping enough. I think the problem now is too much pressure. I need an electric pump that only puts out 1 to 1.5 PSI.

[carbking]

With the original Monel steel needle, 3/4 pound is about right; if you are truly lucky, maybe 1 pound.

 

With our neoprene tipped valve, about 1 1/4 pound, maybe 1 1/2 pound.

 

The mechanical advantage of the float just won't permit more pressure.

 

What you need is a regulator with a bypass. Run an additional "return" line from the regulator bypass to dump into the TOP of the fuel tank.

 

The bypass is far more important than the brand of pump or regulator.

 

Jon

[carbking]

One other possible "bandaid".

 

MAYBE a smaller orifice valve seat could be used with somewhat higher pressure.

 

It has been too many years since I set up this type of equation, but perhaps you could convince one of the retired engineers here that they needed a challenge.

 

You would need to measure the mechanical advantage of the float pin arrangement and the buoyancy of the float.

 

The orifice should be 0.125 (1/8th inch).

 

The seat thread is 27/64 x 22.

 

Jon

[nearchoclatetown]

Wonderful car. I have never seen one burn to the ground using a vacuum tank. But I have seen several DBs that did using an electric pump. A used or rebuilt vacuum tank is cheap compared to a major fire.

[87TT]

10 hours ago, carbking said:

With the original Monel steel needle, 3/4 pound is about right; if you are truly lucky, maybe 1 pound.

 

With our neoprene tipped valve, about 1 1/4 pound, maybe 1 1/2 pound.

 

The mechanical advantage of the float just won't permit more pressure.

 

What you need is a regulator with a bypass. Run an additional "return" line from the regulator bypass to dump into the TOP of the fuel tank.

 

The bypass is far more important than the brand of pump or regulator.

 

Jon

I was contemplating a bypass. easy enough to do once I figure out how to get it into the tank. With all the steep grades around here and the  heavy traffic, I am just a little afraid of the vacuum tank. I may try to do a tank with an assist pump.

[nearchoclatetown]

Just keep in mind, my buddy that had an electric pump JUST IN CASE had a fire that cost over $10000 to repair and it didn't even get into the dashboard. 

[87TT]

I really do appreciate all the help and advice and know it is all good' My Dad had a 1915 DB touring car that he drove across country once and from SoCal to Indiana once. I drove it with him to a DB run in Salem OR from SoCal, 850 miles. He drove it all the way up Pikes Peak in 3rd gear. All with an electric fuel pump on it. I'm not saying all this to argue the wisdom of the vacuum tank, it's just that I want to drive it more than just car shows and parades.

[nat]

     My 24' runs without a hitch or burp..... Except on long inclines when it will occasionally give a, (lean fuel mix), bark from the carburetor.  

     I, (ain't in Kansas or Idaho but now), suspect that to be caused by similar conditions that prompted your father to install an electric pump.

     Perhaps that's the nature of the beast.  Maybe my vent valve doesn't seal completely.  

     I'll report any new wrinkles that emerge or make something up if I get bored.