VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1927 Chev - Vacuum Fuel Pump / Running out of Gas

Hi Guys, our 1927 Chevrolet Landau Sedan with 1928 engine and Stewart Warner vacuum fuel pump, runs great 95% of the time, but runs out of gas when going up steep inclines for an extended period of time. We live in a relatively mountainous region of British Columbia, and the car only bogs down and runs out of fuel on rare occasion and only after climbing steep roads for long periods of time (15 minutes or so). Our guess is that going up hills reduces the vacuum and effectively slows down / stops the vacuum fuel pump from functioning.

Recognizing that many will consider this heresy, we are considering adding a low pressure electric in-line fuel pump to supplement the fuel delivery system. The question though is will an electronic fuel pump work with the vacuum fuel pump ? We were thinking of installing the electric pump in the fuel line just after it exits the main fuel tank, and leaving the Stewart Warner vacuum system in place as it is. Will this work? Should we consider different options?

Also, just as an FYI, our car is not a show car, and we just want to drive it and enjoy it.

Your help and guidance is greatly appreciated.

Chuck & Brad

There are a bunch of us that tour with our 4 cylinders that have added an inline electric pump. The vacuum tank will take care of almost all situations particularly if in good condition (no leaks) and the driver only pushes down on the gas pedal to the point that the engine still tries to accelerate. After that all you loose is vacuum, gain is richer harder to burn mixture, reduced horsepower and over heating. If you hook the pump to a push button switch, when it first coughs push the button for 10 seconds and continue on your merry way.

I mount the pump 1/2 way between the tank and tank, mainly because I purchase 5 foot sections of brake line from my local parts house, fabricate by hand the gas line and put the pump and filter between the two pieces of tubing. Hides inside the frame rail behind the splash apron so is difficult to see.

Chipper, thanks so much for the information and quick response!

Just a couple more questions:

- What pressure output pump should we purchase (or does it matter)?
- Can the electric pump be hooked up to run all the time, or is it best to hook it up to a pulse switch for occasional / as needed use, as you have initially suggested? If you could explain why this is best, that would help our understanding.
- Any specific brand or style of electric pump you suggest ?

Thanks Again, Chuck

As long as you only use the pump to add a little gas to the vacuum tank the pressure does not matter. It may determine how many seconds it takes to fill the vacuum tank.

I do not recommend running the pump all the time. Pressure regulators are required that have proven to be unreliable when fraction of a pound pressures are required. I use a toggle switch because that is what I had but pulse switch is better as it is harder to forget you have the pump on. Overflowing the vacuum tank with gas is not a good idea.

I bought my pumps from www.oldtimeparts.com Duluth MN Seem to work well with alcohol containing gas. Reasonable price too. The sell them on eBay.

Hi Chipper,

Can we simply add the electric fuel pump to the existing fuel line, or do we need to have a separate fuel line just for the new pump?

I ask because I am wondering if the vacuum pump will still be able to pump fuel if we do. Thanks.

Yes, the pump will allow the vacuum tank to work even if the pump is turned off.

Do you really need an electric pump? I drove my 1925 Roadster to the top of Pikes Peak on the stock vacuum tank. I even had a passenger with me.

I have not used the auxiliary electric pump on my '28 Coupe to supplement the vacuum fuel pump except when it has not been run for a number of months. That includes climbing to Logan Pass on the Going to the Sun Highway in Glacier Park, MT. The key is not to push the accelerator pedal past the point where it no longer increases the speed.

Thanks very much to everyone for your input on this, regarding the addition of the electric pump, pulse switch, and how best to drive. I must admit that I was likely pushing the car harder than I should have going up some of the inclines, and that likely contributed to the issue.

That said, I am sure the electric pump will help, and give us peace of mind, that the car won't run out of gas. As you can appreciate, it's a bit disconcerting when you are halfway up a steep hill, and the engine conks out.

We'll strive to get this installed this weekend, and give it a test run.

Thanks Again Guys ! - Chuck

It is almost an automatic response to keep pushing the gas pedal down when slowing as you climb a grade. Have to keep telling yourself to down shift, back off throttle. Then rarely will you run out of gas or vacuum. Of course the tank is lower so gas has to be pulled higher when going up hill. Could always back up the hills like the Model T guys did. Not fast but gets you to the top.

explane the backing up the hill part, i thought that was for a a tank that was almost empty and the outlet from the tank was on the front of the tank? no?

It works for a modelT Ford because it is gravity fed, don't work so good for a Chevrolet with a vacuum pump. Don't keep the trottle wide open and lug the engine. The fuel reservoit in the Stewart Warner fuel pump holds enough fuel when it is full to climb most hills, if you are climbing a looooong grade down-shift rather than lugging the engine with the trottle wide open. go to second gear, I have seen one steep grade in New Mexico that made 1st gear necessary for over a mile. This is why I have a 6volt fuel booster pump mounted at the fuel tank end of the fuel line with a toggle switch mounted near the steering wheel.Try to find a gear that you can pull the grade in mid-range of the rpms and just chug along, don't wind out the engine, be sure you can still add rpms if you need to. The vacuum should be adequate to pump fuel. Also try to keep your additional weight low, extra passengers,ice cooler large tool boxes spare parts to a minimum when touring the mountains with the old fours. It isn't too bad an idea to stay in front of a 28 or 27 truck with a good front bumper, just in case your engine stalls out. Old Chipper's Canopy Express or a big old fire engine can push your little roadster or sedan without too much strain and pain!

490 Chevys, Model T (yes a Chevy) trucks are gravity fed but seem to climb well forwards.

Old Chipper's Canopy Express only pass three on an upgrade. Hiker on shoulder, bicycle rider and speedster with mis-adjusted carburetor (made more black smoke than speed). So keeping in front of the CE should not be too tough. It loves second gear!