electric fuel pump-stepdowns

OK, let's talk about why an electric pump. It has to do with the viscosity of the gas. Since the folks took out the lead and then started adding ethonol the gas is much thinner and our fuel pumps are not as efficient at moving the gas. Also, because of this the heat of the manifold causes the gas to boil away or vaporize etto vaporlock. So, since the electric fuel pump puts positive pressure gas to the carb, it does not always solve the vaporlock. You need to add a gas line return to your system. I like to pick up a gas filter with two tubes on one end and one on the other so as the pressure builds within the system the overflow can return to the tank keeping constant cool gas in your line. Brand of fuel pump is not important--any 6volt will do. And you want to run it all the time.

I must advise not just any electric pump(EP), but a "free-flow" type if it will be installed inline. Otherwise, when the car is being operated without the EP, the MP (mechanical pump) will starve for fuel as it won't be able to draw gas up the fuel line. Free flow type specifically is the Air-Tex Solenoid type. The Carter rotary vane is the best for an EP only, but can restrict flow if the vanes stop in front of the outlet. Also, I frankly,could not find a good/safe location to conveniently mount that EP behind the rear axel on a stepdown. Maybe someone knows. Do not use a 12 volt Garator( gear driven) pump( no 6 volt are made by Carter). Fuel only passes when the pump is running... NG for part time usage. Park W. put a great illustration of a rotary vane on the forum a couple of years ago. I also tried the return line (with a .030 orifice) as Walt M advised, but had little effect, as most of my issue was a weak MP and Arizona heat cooking the fuel in the bowls. Solved by sending the fuel pump out for a GOOD rebuild, moving the fuel line and covering it with Mylar. Covering the MP with a Mylar "blanket" and adding three Ford carb gaskets (phenolic) below the carb heat shields on each WA-1. So far so good. The EP should not flood since there are internal regulators, but if it does a GOOD pressure regulator will be in order. AND no winter gas in the summer.

In addition to the heat, the vacuum the pump creates causes the gas to boil also. Remember high school science where water boiled at room temperature? There is a screen in the pump which has to be kept clean or it will increase the vacuum, increasing the tendency to vapor lock. A mechanical pump can't pump vapor. A cooler with a bag of ice cubes can be used to condense the vapor and get your pump going again. Keep it running if you can to keep cooler gas flowing. That's the value of the return line, probably the best fix.

I have an electric on the Hornet, under the middle of the car with a $5 clear plastic filter in front of it. Easy to see how dirty it's getting and to change. I can switch it on and off under the dash. Only need it if it's set for several days or overheating.

BTW, clothes pins on the fuel line don't work..only for old wives.

Back to Middletom's original post . . . regarding the filter, it's not just something to consider, it's more like mandatory. Most electric pumps come with a manufacturer's statement that the warranty is void if there's not a filter between the tank and the electric pump.

While Brownie's and Walt's remarks about the return line are quite valid, many of us have found that even without the return line, our problems are resolved by just having the electric pump to switch on when the engine falters in high heat situations.

Here's the rotary pump with check-valve bypass, on my '47

Never use copper in your gas line system. It becomes brittle, cracks, leaks--if it is near a power source you most likely will have a fire. Once on fire an entire car will burn. It takes less than four minutes with a car fire to have the gas tank explode. Just saying,

Brownie, maybe I've just been lucky, but I've had copper tubing on cars for decades, with no such problems.

My '28 Essex still has it's original copper petrol tubing. You do have a point though, as copper does work harden, but there is very little movement anywhere, as the pipe is clipped well on to the chassis. Only point of slight movement would be from the bulkhead to the vacuum tank, and from there to the carby, but I have a coil in here to absorb vibrations, and the engine does'nt wobble around like the later rubber mounts. And copper doesn't rust. I did have the oil pressure gauge crack off at the joint and pumped all the oil on to the road 45 years ago. replaced it with a flexible line, no problems since, but I probably should replace that again, as the flexible lines are probably more likely to fail than the copper.

Bundy weld tubing good too, fuel and brake speciific. Get it by the coil from McMaster or most parts stores have various finished (flared w/ fittings) lengths.