I've got 3 Rochester 'B' carbs on my Chev 235 I6 and if the car sits for a week or two without being run the whole fuel system is dry and I either have to prime it or crank the daylights out of it till the fuel system fills up and then it starts just fine. So I've got 2 questions - Can I use an electric pump in series to push fuel through the diaphram pump to prime/fill the lines? Some aircraft I've flown have an electric boost pump used on take-off only, and I think this is how it's done. I would put the electric pump between the tank and the diaphram pump. Second question - how far will an electric pump draw from the tank? Could I put the electric pump in the engine compartment? My reason for not going to electric only is I eliminate the need for a pressure reducer.
I think its possible. although you might have the check valve on your mechanical pump going bad, possibly replacing it with a Good U.S. made pump (if you can find one) could cure the problem with out having to go the primer route
OT response. LOL when I was scanning the page I read "pushing through a diaphram"--my mind went into the gutter
It should work. Make it so you can shut it off as soon as the fuel gets to the mechanical pump. As you stated the biggest problem with the electric pumps is their pressure. Your carbs would only like to have 2 or3 lbs at the carbs. Electric ones are WAY above that in most cases.
BUT , Can the low pressure low volume mechanical pump **** through the electric pump , OR would another line to the mech pump be needed when the electric isn`t running ?????????????? I have a similar concern with one of my vehicles and would love an answer ! Chryco
you could run a byp*** with a one way valve around the electric so that when it turns off gas will still flow on by. by the way, modern cars with electric do re prime the pump every time the key is turned to key on-engine off. it runs for about 2-3 seconds. thats all you really need, if it still isn't prime just turn the key again. you could just wire the pump to a switch, or switch/relay and just flip it on for a few seconds before starting the car. a primer pump could be so tiny too
I'm running a set up like this on a jeep pick up with a 360. Don't recall the brand, but I got an on-line electric pump at napa and ran it through the stock pump. Works fine, has for years. I wouldn't mount it in the engine compartment. Tried that at first and went through pumps quickly. I mounted the electric pump too high as well- they don't seem to like to draw the fuel. Once i lowered it below the tank and straightened out the inlet line its worked great.
The 2 to 5 seconds of the OEM Elec Fuel Pump running, is to Pressurize the fuel injectors. for quick startup. Turn the key to run, some cars you can hear it. And Yes You can pull thru, a in tank elec pump with a Manual pump on the engine.
If the electric pump is a diaphram pump, like one of the small Facet pumps (available in low pressure), then it should work. If the electric pump is a rotary vane then you might have some problems. Electric pumps should be mounted close to the fuel tank (certainly within a couple of feet) and lower than the fuel tank if possible.
I Don't see a mechanical pump drawing fuel thru the electric pump. A secondary line may work to solve that issue. But a additional check valve still needs to be installed . I had the exact issue on a Pontiac tri-power set up. Let it set a week and needed to prime the center Carb or crank & pump until some fuel got into the engine. I just had a small squeeze bottle of fuel on the shelf as this was not an everyday issue, only if it sat for extended periods. Can only be a few culprits, no check valve, bad check valve, fuel evaporated out of the bowls.
The electric pump will push fuel through a diaphragm pump. The flathead guys do it to prime the carbs when they sit for a few weeks. There is one potential problem... if the mechanical pump diaphragm cracks from age and or the modern gas, the electric pump will pump gas into the crank case and dilute the oil potentially wiping out the engine. I wouldn't do it because you can never tell from the drivers seat when or if the diaphragm fails.
Electric pumps are made to push, not pull. If you buy a new one, a quick check by ****ing on it will tell you if it will let fuel through.
Marcosmadness has by far the best idea, use an electric diaphragm pump located near the tank. That will fill the entire fuel system, and the mechanical pump will easily draw fuel through the electric pump when it is not running Just fit a push ****on to operate the Facet, you will "hear" when the system is primed and full.
I have the similar problem with my 283, I have a new Edelbrock carb, with an Edelbrock fuel pressure regulator (set at 5 lbs.) Everything works just peachy, but I have to crank it when it sits for awhile. All of this electric fuel pump theory gives me the heeby-jeebies, to be honest. Has anyone ever rigged up a hand pump primer to draw the fuel to the carb?
if you want to run an electric pump, Holley makes the special low pressure regulator for what you need, it goes down to 1.5 psi if needed. it's really the only option for a low pressure regulator like it, unless you go to an aeromotive, and it's WAY more expensive.
What about just putting the one way check valve in your fuel line before the manual pump to keep the fuel from draining back to the tank.
I use a cheap 2' square low pressure 12V electric pump to prime the two Holley 94's on our flattie. It is mounted on the frame about half way up right behind the drivers door of our 51 Merc. The only time I use it is the prime the carbs @ the car has been sitting a few days. The stock diaphragm pump on the flattie puls fuel thru it just fine. The electric pushes fuel thru the diaphragm pump just fine. Plus I would have a backup to get me home if the stock pump took a dump..
I'll try it & let you know what happens. It seems a tad easier than the whole electric fuel pump thing.
I run the electric through a mechanical pump and so does my buddy and it is not a problem. My electric pump runs continuosly. You don't have to shut it off the mechanical acts like a regulator
Ran that set up years ago. Put the electric pump close to the tank, switch to turn on/off the electric pump.
Sounds like a 20 dollar cure for a 10 cent problem. Figure out where the fuel is going and repair the problem, or drive it (or at least start it) more often. You can push fuel through a lot of mechanical pumps but I don't know about yours specifically. You electric will work better if you mount it near the tank but you can probably get away with mounting it in the engine compartment. I've run them that way in a pinch no problems. If you invest in a pulse pump as opposed to a gear pump you can get away without a regulater. Its been done that way for eons.
I'm not positive about low pressure pumps but I have one of those little box pumps that hang on the wall at Autozone and OReilly's for under 40.00 bucks on my daily driver. I ran it on another car as the only pump and swapped it to the truck when the stock pump ****ped out. with a toggle switch it works great to get fuel up through the lines and can be shut when the regular pump is running. In fact right now I don't even have it hooked up to the wiring, it's just back there for the ride.
I think it is the gas, have the same problem on two cars. One has a new pump and new carb. It works just like the older set up. Sets for a week, have to prime them and crank like hell
the old Walbro type pumps like this are still made, they have a bunch of them in different specs, some of them are very low pressure and have a dry lift of 24 inches, this is what you need if the pump is above the fuel tank. http://www.autoperformanceengineering.com/
Where you are it is hot unless you're up by Flagstaff, right? If you are in the hot part of AZ your problem is probably due to evaporation. The poster (not to be confused with Poser) is up in Pennsilvania (I think) shouldn't be the same problem. A lot of times what happens is that the carbs leak then before you can light it off you have to fill them back up. Couple that with an older pump with a weak diaphragm and you have to do some serious cranking prior to lighting it off.
A hidden fuel tap is a splendid idea. It also creates one extra little problem if some low life s*** tries to steal your ride. A simple swinging check valve may leak down very slowly, and not be able to seal properly The mechanical fuel pump may not have the suction to open some types of spring loaded ball check valves that are designed to work at much higher pressures. Not saying it won't work, but select your check valve very carefully. Another idea might be a 12 volt solenoid valve wired up to the ignition. This will give a very positive fuel cut off, and will fully open with ignition power applied, you just need to find something with enough flow and that is compatible with gasoline. If that were hidden under the car, with a secret switch it could do two things....
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