Fuel System: Carburetor

[truckguy]

Hello, I have the Carter BBR-1 carburetor on my 55 E5 truck. After sitting without use for more then 4 days it would take a long time to start. I believe the gasoline in the carb drains back into the fuel tank. This year, it is slow to start even the next day! Does anyone have any idea what has happened here?

[Mike Van Veghten]

Been talked about a lot here.

The fuel does not drain back to the tank. Essentially impossible for that to happen, the way the system is designed.
What's happening is happening to most everyone..."evaporation". There are a couple of places in the carburetor that the fuel bowl is open to the outside air. The bowl vent is the main place the evaporation happens. Hence, empty fuel bowl in a coupla days. Carburetors with larger fuel bowls...while still having the same problem...have more fuel to evaporate, so they will take a little longer to become dry enough to not have enough to start the engine.

An electric fuel pump will help alleviate the long cranking times by putting fuel back into the bowl at a much faster rate than a mechanical pump will do. It will also fix most vapor lock problems.

Mike

[truckguy]

Mike, thank you. Why do you think the issue is far worse than it was last fall or for the last 4 years that I've had the carb?

[gordr]

Mike, thank you. Why do you think the issue is far worse than it was last fall or for the last 4 years that I've had the carb?

Ethanol-blended fuel, and fuel is now made with more "light ends" in it, since all newer cars have sealed, pressurized fuel systems that can tolerate fuel with a high vapor pressure. Modern fuel is made to meet the needs of modern cars with EFI.

If you want to drive your Studebaker regularly, I think the best approach is to mount a low-pressure electric fuel pump back near the tank, and remove the mechanical pump altogether. Power the electric pump through a relay wired such that the pump runs when cranking, or when the engine is running and providing a tach signal or oil pressure signal to the relay. That protects you in the event that you are in a wreck that stops the engine... prevents the fuel pump from continuing to run, feeding a possible engine-room fire.

[rockne10]

I mounted an electric pump near the tank, with a momentary switch under the dash. Only use it to prime the carb, as the mechanical pump works fine.
Agree with Gord; the ethanol fuel loves to evaporate. In addition, most of our older carbs have been rebuilt to the point where the chromation of the carb body has been worn away. The carb body is porous and the original chromation sealed it. There are folks who re-chromate the body in the course of a rebuild. It helps but does not solve the ethanol issue. Adding a few ounces of Marvel Mystery Oil to each tank of gas will also help a little.

[doofus]

There is a bbr1 bowl assy in a tub upstairs. pm me if needed and i will inspect it for you,yours for shipping. Luck Doofus

[TWChamp]

Some guys have reported good luck by using a quart of diesel in a tank of this modern day crap gas.
I think I'll also give that a try this summer.

[jackb]

Diesel & MMO are supposed to be good against vapor lock. I sometimes throw in some ATF or end of the can oil in with a tankful. ..... Haven't seen vapor lock since Texas....

[jclary]

Regarding a long cranking time after sitting...it has been quite a while since posting this before, so posting again might be appropriate. Now that our vehicles are over a half century old, and been through several owners, it is difficult to know every detail of its mechanical care and history. All of our carburetor's housings were "sintered" against porosity. A process whereby the casting is impregnated with a special chemical to prevent gasoline from leaking through the casting body. If, someone in the past has used something like lacquer thinner to clean the carburetor, it has damaged the casting's chemical seal. Also, I'm not convinced that, over time, the sintering does not degrade on its own. Add to that, the quality of modern gas, and we have a "trifecta" of excuses for failure, regardless of facts to back it up.

Another thing to consider, the bowl (reservoir of fuel) is vented to atmosphere. Therefore, the more it sits, the more gas evaporates. Our standard old style fuel pumps supply low volume at low pressure. The more gas that has evaporated from the bowl will require more strokes (cranking) to refill it. Add to the cranking, a worn out accelerator pump, and the ability to get the "squirts" of gas adds to the problem.

One thing I have done is to install one of those period correct glass bowl ceramic element gas filters at the carburetor inlet. What that has done is to give me a small reservoir of gas (in that little filter bowl) that helps refill the carburetor quicker. Even then, more cranking is required if the engine has sat for several days before starting again. I think the electric pump assist would be the ultimate solution, but I have not felt the need to try it myself.

[ETLMT]

Been talked about a lot here.

...
An electric fuel pump will help alleviate the long cranking times by putting fuel back into the bowl at a much faster rate than a mechanical pump will do. It will also fix most vapor lock problems.

Mike

DAMMIT!!!
I had a friend that knew more about cars than I did and when we were working on updating the fuel line he said it was stupid to have an electric fuel pump in it because "even a plane works with just a mechanical pump" and he removed it... Now I wonder if I still have it.

[StudeRich]

Don't worry about the loss? of your Electric fuel pump, if your Stude. runs good and starts even reasonably well without it, you will never miss it.

I have been driving Studebakers here on the West Coast where we have had this unleaded, 10% Ethanol for over 20 years and never had ANY need to add a "Rattle Machine"!

[bensherb]

"Rattle Machine"!

"Rattle Machine" ? Buy a decent pump! My electric pump, and the ones on all my carbureted cars are so quiet I've added a light in paralell with them just so I can tell when they're turned on.

Here on the west coast where it actually gets warm, the modern crap fuel we get will evaporate all but completely from the AFB on my R1 within an hour of shutting it off when the engine is up to temp. Furthermore, if I fill the tank on my motorcycle and run that tank out immediately, I will get around 57 mpg, but if I fill the tank and let the bike sit for a week or two, I only get about 36 mpg. Evidently 38% of the fuel in the tank will evaporate in that couple of weeks. 26 of the last 31 days has been over 100F here, the highest was 112F.

[Mrs K Corbin]

#1 Stop using Ethanol fuel..... plenty of reasons why.

Me, myself, I have a mustard bottle full of gas that I use for priming.. it helps me.

[Skip Lackie]

#1 Stop using Ethanol fuel..... plenty of reasons why.

Agree -- if that's practical. But if you have to drive 150 miles one way to find it, that's not a very practical solution. Nearly all the US urban areas, and most of their surrounding suburban counties, too, are ethanol-only regions.