fuel pump

RonS · August 2009

I'm thinking of removing the dual diaphram AC fuel pump on my Hornet and going with a electric pump only, but of course the vacuum booster for the wipers will be lost. Has any one used a vacuum tank to maintain wiper action under load? If so, which tank and where did you mount it. OR,what about running the fuel line in series,ie,electric in the rear by the gas tank,line to inlet on the mechanical and out to the carbs.I fear a leak in the pump will fill the crankcase with gas. I have tried every thing to beat fuel starving in Az. I even tried Walt Ms fuel feedback line ,no help. I do suspect that I am sucking air I intend to check the pickup tube and make some design changes. I woud like to keep the original look, but I believe that damage to the mechanical pump will occur if gas does not pass through it to lube the diaphram, so I can't just bypass it and leave it there.

RL Chilton · August 2009

Ron-

If your mechanical pump is in good shape, why not add an electric pump in the same line back by the gas tank?

This is a really good idea for Hudsons that "sit" during the week, or even over the course of several weeks without getting fired up. Hooked up to a remote switch (usually around the dash somewhere), just fire up the elec. pump and wait 7 or 8 seconds until you fire the ignition, and voila', you've filled up the bowls in the carbs and she's ready to fire. Eliminates heavy cranking on seldom-fired engines.

Another advantage is being able to have a backup out on the road if the mech. pump failed. Fire up the elec. pump and make it on home.

If you go this route, remember that elec. pumps push, but don't pull. Gravity-feed the pump (mount it below the gas level in tank) and it will push gas as far as you want to push it.

Ol racer · August 2009

I think your vacume tank is a good idea since cars with wild cams use it on the street to increase vacume to their brake booster; I use electric wipers in my Hudson's and mount an electric pump near the tank. I found chevy V8 block off plate will cover the pump hole if want to remove pump.

Russells suggestion works good too. I have that identical toggle set-up on a '53 Hornet that sets for months running thru a Pinto pump. After starts I turn off pump;

Vacume tanks usually mount anywhere near the motor

Even back in the old days some guys were removing dual pumps for fear wearing the cam lobe from tension and/or potential for gas leak into the pan and dealt with slow wipers.

Park_W · August 2009

Ron, that fear of a bad diaphragm letting fuel into the crankcase is why I've never been too keen on running the electric pump all the time. But it's great for filling the carb(s) after the car's been sitting for a few days. Regarding the fuel supply problem, check the gasket under the fuel pump's glass sediment bowl. I found mine was a very porous cork material ... a major vacuum leak that caused me all sorts of trouble until I replaced it with one of a different, non-porous material.

RonS · August 2009

Thanks. Never thought about the gasket on the pump filter. I'll ckeck it out. I would like to remove the pickup tube in the gas tank. How much gas can I leave in the tank or should I remove it all?

[Deleted User] · August 2009

RonS wrote:

I'm thinking of removing the dual diaphram AC fuel pump on my Hornet and going with a electric pump only, but of course the vacuum booster for the wipers will be lost. Has any one used a vacuum tank to maintain wiper action under load? If so, which tank and where did you mount it. OR,what about running the fuel line in series,ie,electric in the rear by the gas tank,line to inlet on the mechanical and out to the carbs.I fear a leak in the pump will fill the crankcase with gas. I have tried every thing to beat fuel starving in Az. I even tried Walt Ms fuel feedback line ,no help. I do suspect that I am sucking air I intend to check the pickup tube and make some design changes. I woud like to keep the original look, but I believe that damage to the mechanical pump will occur if gas does not pass through it to lube the diaphram, so I can't just bypass it and leave it there.

You have a very bad pick up tube or the screen in the tank where the pick up tube goes into is blocked. 48 to 53 had this set up. Walt.

[Deleted User] · August 2009

I'm also having a bit of trouble with a dual chamber pump.

Yesterday evening while tinkering with the '49 w/308, I wondered what the A/F ratio would be with the wiper vacuum unhooked from the pump and blocked off at the manifold. I instantly went unbelievably rich and I would have been able to recognize it even without the carb meter. Way rich.

Is there a way I can fix that without a complete overhaul? What part of the pump would be leaking that much vacuum?

I can't run with the upper chamber blocked off, because it "knocks" slightly without the engine vacuum pulling on it. I don't know if that is hurting anything, but a noise like that isn't something I like to hear. When I hooked it back up, the knocking was gone.

This is really a pain in the tail - because it means that all my carb tuning has been skewed by the vacuum leak. The good news is that I was getting 15 mpg like that - who knows what my mileage will be once I track down the air leaks?

Mark

[Deleted User] · August 2009

`Hudsonator wrote:

I'm also having a bit of trouble with a dual chamber pump.

Yesterday evening while tinkering with the '49 w/308, I wondered what the A/F ratio would be with the wiper vacuum unhooked from the pump and blocked off at the manifold. I instantly went unbelievably rich and I would have been able to recognize it even without the carb meter. Way rich.

Is there a way I can fix that without a complete overhaul? What part of the pump would be leaking that much vacuum?

I can't run with the upper chamber blocked off, because it "knocks" slightly without the engine vacuum pulling on it. I don't know if that is hurting anything, but a noise like that isn't something I like to hear. When I hooked it back up, the knocking was gone.

This is really a pain in the tail - because it means that all my carb tuning has been skewed by the vacuum leak. The good news is that I was getting 15 mpg like that - who knows what my mileage will be once I track down the air leaks?

Mark

Don't try to block off the vacuum in your fuel pump. as the same lever works both diaphragm. Bad news. Walt.

RonS · August 2009

Thanks Walt. I intend to pull the tube soon. Can the screen be removed as well.I remember a long time ago that the only way to get it out is to cut the tank and reweld it. But, that still doesn't account for the fact that the starvation only occurs when + 90 degrees and on a fully warmed engine. Never in the winter, or at least until now. Another factor is the location of the electric pump. For convenience I mounted under the passenger foot well. Too far foward. Soo, I am going to replace the whole fuel system from tank to carbs. Run an electric pump only,mounted by the gas tank, Bloc off the AC double action(removing the Cam arm) replace it using the vacuum ports.I might add a vacuum tank and check valve to keep the wipers from stopping under load. What da ya think?

[Deleted User] · August 2009

RonS wrote:

Thanks Walt. I intend to pull the tube soon. Can the screen be removed as well.I remember a long time ago that the only way to get it out is to cut the tank and reweld it. But, that still doesn't account for the fact that the starvation only occurs when + 90 degrees and on a fully warmed engine. Never in the winter, or at least until now. Another factor is the location of the electric pump. For convenience I mounted under the passenger foot well. Too far foward. Soo, I am going to replace the whole fuel system from tank to carbs. Run an electric pump only,mounted by the gas tank, Bloc off the AC double action(removing the Cam arm) replace it using the vacuum ports.I might add a vacuum tank and check valve to keep the wipers from stopping under load. What da ya think?

The only way to not use the screen is to drop the tank and with a long screw driver open up a hole in it. This is done with the gas gauge sending unit removed. Try your electric pump first and if all is OK, forget about the pick up tube screen. Vacuum reserve tanks are available or go to a junk yard and get one off a car with air condition. Walt.

RonS · August 2009

Thanks,Walt, sounds like a plan.Ron

fuel pump

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