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Help, 1915 Dodge Brothers Question about Fuel Pressure?


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Posted (edited)

Hello DB Fans, I recently acquired a 1915 DB Touring car, I rebuilt the vacuum pump on the dash but was unable to pressurize the system to get gas to carb. So, I plugged the gas cap vent, got car started but flooded badly. I unplugged the gas cap and no longer get gas to carb???

 

What's the secret to success? How does this system work with a vent or without? My text is 630-608-3978

 

Thanks,

James

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Edited by fozz71
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In order for the pump to be able to pressurise the tank, the tank needs to be sealed. If there is a leak any where including at the top air will escape. If you have a vented cap fitted then no pressure so no flow.

If it works with the vent plugged then the pump is good.

if it floods then you are pumping too much as these carbys work on gravity so one PSI is plenty. 
Perhaps another early car owner can help with how to operate this but I would suggest a couple of pumps to get it going and regular pumps during travel to maintain pressure.

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Correction, I now understand that the hand pump is used to provide initial LOW pressure in the tank for starting, there is an air pump on the engine to maintain this pressure while driving.

It will not work with a vented cap.

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Posted (edited)

Okay so somehow I need to seal my vented cap and figure out how many hand-pumps are enough to get it started. The problem I ran into was flooding while the car was idling. Not sure if my float was bad or the sealed system was incorrect. Both gas caps have vents in them and they are an original style. So that's curious.

 

Edited by fozz71 (see edit history)
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  • fozz71 changed the title to Help, 1915 Dodge Brothers Question about Fuel Pressure?

It either has a vacuum tank or a pressurized system. If early, before 30,000 serial,  it has a hand pump. You should have a gauge to tell you. If you have all that just about any pressure is enough, so if the gauge moves it has pressure. The gas cap for this system is sealed, no vent, and will not fit a vacuum tank style gas tank. Show us some pictures of what you have. If the hand pump doesn't work it needs either a new leather seal or neatsfoot oil. Unscrew the end and check the leather. BUT, you can't flood the carb with the hand pump. So maybe your float is bad or stuck or ?? Sounds like a separate issue. Any idea when the lettering was put on?  Looks like a very decent car. I like original early cars. 

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Posted (edited)

The lettering, I believe, was put on sometime in the 40's judging by the font and aging. This car was produced in July of 1915 by the serial numbers- the entire motor and trans have been rebuilt in the 90's and the rest is original. I even have the top irons and material. I rebuilt the hand-pump and added new leather and it now works. Just have to seal the system by plugging the vent in the gas cap. I am cleaning the carb now and making sure the float isn't stuck. 

 

Here are some pics of the car- some are before cleaning and some are afterwards.

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Edited by fozz71 (see edit history)
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15 hours ago, fozz71 said:

The lettering, I believe, was put on sometime in the 40's judging by the font and aging. This car was produced in July of 1915 by the serial numbers- the entire motor and trans have been rebuilt in the 90's and the rest is original. I even have the top irons and material. I rebuilt the hand-pump and added new leather and it now works. Just have to seal the system by plugging the vent in the gas cap. I am cleaning the carb now and making sure the float isn't stuck. 

 

Here are some pics of the car- some are before cleaning and some are afterwards.

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Even tho I am In Australia that is one car I would Love to own 

 

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Fozz, that would be correct cap. It should have a gasket too as it appears you are using. Are both fuel lines cleared of any crud. One brings air from pumps and other allows gas to flow to carb. Make sure all fittings are tight. You should be able to fill the bowl and start it with line off to make sure the pump pushes fuel front. The pump on the side of the engine is kind of crude, steel piston on brass cylinder with no O ring or seal. It doesn't take much pressure. I know cars that show no pressure on the gauge and still run fine. Fozz, have you ever heard of Gibbs penetrating spray? If not you need to find some. You can spray down the whole car to protect it. Gibbs stays kind of wet for months and will keep it from rusting. AND, you can paint over it if you ever decide to. I have a car in storage that gets a can every year all over. Ron, I agree. The more I see of this car the more I like it. 

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Well, I learned something today. I tried the cap you show with no stem for vent, a cap with a vent, and a winged cap for early cars and they all have the same thread. There is a change in some as the changed the pitched, I think from 12 to 14 tpi. I thought there were different sized threads for each. My cap like yours, with no stem, has a vent hole. Some do not. I swear they changed stuff or didn't change stuff just to confuse us 100 years later. 

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Posted (edited)

Thanks guys, your help has been invaluable. The system seems basic enough and the car runs great but I must have a tiny little hole in my pressure lines, because it won't bring gas to the carburator. The connections are tight and I can keep the car running well by filling the bowl with gas, but won't suck it from the back tank. I can even pump the dash-primer and bring gas to start it but the motor doesn't keep it going.

 

Thanks for the help, fellas!

Edited by fozz71
fat finger (see edit history)
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@fozz71I'm not familiar with the Dodge pressurized fuel delivery system, but the Pierce-Arrow system has an occasionally troublesome (dirty) check valve next to the engine-mounted pump which will produce your symptoms--hand pump allows starting, but the engine-driven pump won't deliver fuel to keep it running.

 

If you do have a check valve near the pump, I suggest (1) cleaning it on General Principles (Pierce guys have to use a magnet to lift the ball on some models), and (2) put a Mity-Vac or similar on the fuel line just before the engine-driven pump to see if it will pull fuel.

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Fozi, a friend suggested checking the tube that runs from gas line inside the tank. If this car sat for a long time it may have grown shut. It goes to the bottom on the tank. May need to empty tank, take out drain plug and blow compressed air from the outside fitting to clear it. 

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  • 2 weeks later...

I just acquired this car from James and am very excited about it!  Seeing as it is the worst possible time of year for an air conditioner mechanic to take on a car project, progress towards getting it on the road may be very slow for a moment, other than the fact that I believe my car collector father to be almost as excited about the new arrival... he is retired with much more free time. 

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  • 2 weeks later...

Air was just gushing out of the fuel gauge cap. Removed a modern gasket that didn’t fit well, cleaned the original with some spit and my finger, and had a pressurized fuel system about five minutes after pushing the car off the trailer. If I didn’t have a second person to operate the pump on the dash while I stood behind the car to listen, I would have never found it. 
 

She runs great! 

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On 5/25/2021 at 6:27 PM, nearchoclatetown said:

Well, I learned something today. I tried the cap you show with no stem for vent, a cap with a vent, and a winged cap for early cars and they all have the same thread. There is a change in some as the changed the pitched, I think from 12 to 14 tpi. I thought there were different sized threads for each. My cap like yours, with no stem, has a vent hole. Some do not. I swear they changed stuff or didn't change stuff just to confuse us 100 years later. 

Looking at the pic of those two caps, I believe one with vent hole is for Commercial Car (Screenside) where the fuel tank is under the seat. The correct one for the '15 should have NO vent hole since it needs to maintain pressure. Nice looking car by the way. 

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