jagnweiner Posted May 22, 2007 Share Posted May 22, 2007 OK, here's the deal. I have a 1925 DB touring that has been a great driver for several years. I have, however, had problems with the last few years with the vacuum tank. After it quit working, I had it rebuilt once by Romar. When I got it back, it still didn't work and I discovered that the float had cracks. I got some parts from another tank to repair and still cannot get it to work. I am not giving up on the vac tank for good, but I want to get this thing running again in the meantime. I would like to install a temporary electric fuel pump that bypasses the vac tank. I'm not concerned about stock appearance and I eventually want to get the vac tank working again, so I don't want to try to conceal it inside the shell of the vac tank.Can someone walk me through how I can do this?Thanks,Scott Link to comment Share on other sites More sharing options...
dwollam Posted May 22, 2007 Share Posted May 22, 2007 I have a 20 touring car with an electric "click click click " type pump AND a vacuum tank. It had the electric already and a goofy setup so I remove the goofy stuff and put the vacuum tank on, leaving the electric in case the vacuum did not work. It worked fine, even through the electric pump with the electric turned off. If I turn on the electric it will just keep pumping and overflow the vacuum tank but I have a switch so I can just turn it on breifly if ever needed to get me in. The electric is mounted under the car along with an inline filter. ALL fittings need to be sealed and correct for the vacuum tanks to work right and the curved vent MUST be open. The float in the carb is very difficult to handle the pressure of an electric pump so a regulator would be required to run it full time. There is also a tiny hole in the fitting on the vacuum tank that the line from the top of the carb runs to. I think that is important as well. The vacuum tanks work well when everything is correct. Hope this helps.Dave Link to comment Share on other sites More sharing options...
wenthur Posted May 22, 2007 Share Posted May 22, 2007 My 24 touring has the electric pump to prime the vacuum tank, if it has been setting a long time, I just got the car and had the vacuum tank cleaned and soldered before I started truck 1/4" of rust chips in the bottom. After turning on electric pump for 1 min. the thing fired right up. the switch is a N.O. toggle on the firewall, since I have to open engine cover to turn on and off gas, at vacuum tank, the switch is handy place. Mike Link to comment Share on other sites More sharing options...
jagnweiner Posted May 23, 2007 Author Share Posted May 23, 2007 What kind of PSI should I be looking for at the carb? Link to comment Share on other sites More sharing options...
dwollam Posted May 23, 2007 Share Posted May 23, 2007 As low as possible. Remember the original is just gravity feed.Dave Link to comment Share on other sites More sharing options...
jagnweiner Posted May 24, 2007 Author Share Posted May 24, 2007 Thanks, Dave. How low is low? I can get a pump that is 1.5 PSI. Do you think that is low enough or will I need a regulator?-Scott Link to comment Share on other sites More sharing options...
RickBrinker Posted May 24, 2007 Share Posted May 24, 2007 You need .5 psi or lower. Link to comment Share on other sites More sharing options...
jagnweiner Posted May 25, 2007 Author Share Posted May 25, 2007 OK, tonight I went out and found a pump and a regulator and some copper tubing to create my bypass. Now my question/problem is this. The pump says it is for 12V negative ground systems only. Is there I way I can make the pump negative ground while the rest of the system is positive ground? There is a switch already wired from when it previously had an electric pump. It appears that it got its power from the ammeter. Would this have something to do with it? Thanks,Scott Link to comment Share on other sites More sharing options...
jagnweiner Posted May 31, 2007 Author Share Posted May 31, 2007 Any thoughts on this last question? I'm hoping to install the pump this weekend. I'm starting to lean toward just using it to fill the vac tank.Thanks,Scott Link to comment Share on other sites More sharing options...
Jim Anselmo Posted May 31, 2007 Share Posted May 31, 2007 I'll give it a shot (having never installed a pump myself).... If the pump only has a single wire coming from it then I would guess that the body or mounting plate of the pump is the negative connection and the single wire is the positive connection. If this is the case, when you mount the pump you need to isolate the body or mounting plate from the chassis and connect the negative connection to the body (or mounting plate) of the pump and the positive connection (wire) to the chassis (since the DB is + gound). If the pump has 2 wires then check to see that there is no continuity from the negative wire (black) to the body or mounting plate on the pump. If there is no continuity you should be OK to hook the positive connection (red wire) to the chassis and the negative connection (black wire) to the ammeter. If there is continuity then you need to isolate the pump from the chassis.Hope this makes some sense... Link to comment Share on other sites More sharing options...
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