Faulkner Posted March 31, 2021 Report Share Posted March 31, 2021 9 hours ago, Sam Buchanan said: The doodad is a filter, put it on the tank side of the pump. Put an ohmmeter across the each wire and the pump housing, no continuity indicates the wires are floating free of the housing. If this is for either polarity I'm sure that will be the case. Yup! Thanks Sam. No continuity between the housing and either lead. Quote Link to comment Share on other sites More sharing options...
Faulkner Posted March 31, 2021 Report Share Posted March 31, 2021 4 hours ago, desoto1939 said: I run an electric as a backup to my mechanical pump. Rich, do you mean, both pumps are always running, with the expectation that the electric will pick up should the mechanical fail? Or do you switch the electric off? I'm interested in the benefit of the electric pump for starting conditions - i.e., fill the carburetor bowl *before* cranking starts. But if the mechanical is in series with the electrical, might that not act as a flow impediment, depending on the position of the fuel pump arm? That is - will the electric pump push gas through the mechanical pump, regardless of where the cam is when the engine was turned off? Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted March 31, 2021 Report Share Posted March 31, 2021 The mechanical pump will allow fuel to flow through it even with the engine off, the electric pump will simply push fuel through the mechanical pump check valves. But.......the question begs to be asked.....if you have a good electric pump, why would you want to continue to drag that leak-prone mechanical pump along for the ride? It is easy to make a mechanical pump block-off plate. ? Quote Link to comment Share on other sites More sharing options...
kencombs Posted March 31, 2021 Report Share Posted March 31, 2021 That type of pump is not sensitive to polarity, works either way. I would just match colors to the rest of the car, ie; ground the same color. Quote Link to comment Share on other sites More sharing options...
Faulkner Posted March 31, 2021 Report Share Posted March 31, 2021 14 minutes ago, kencombs said: That type of pump is not sensitive to polarity, works either way. I would just match colors to the rest of the car, ie; ground the same color. Oh, cool! Thanks. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted March 31, 2021 Report Share Posted March 31, 2021 13 hours ago, Faulkner said: Rich, do you mean, both pumps are always running, with the expectation that the electric will pick up should the mechanical fail? Or do you switch the electric off? I'm interested in the benefit of the electric pump for starting conditions - i.e., fill the carburetor bowl *before* cranking starts. But if the mechanical is in series with the electrical, might that not act as a flow impediment, depending on the position of the fuel pump arm? That is - will the electric pump push gas through the mechanical pump, regardless of where the cam is when the engine was turned off? No both pumps do not run at the same time. I use the electric pump as a prinming pump after the car has sat for sometime to get gas upto the carb and fill the bowel. I then turn it off via a toggle switch under my dash. I have the toggle switch setup so that the power comes off the ignition swith so when the ignition swith of off then the pump is off. I have run a mechanical pump on my car for 34+ years. If the mechanical pump fails then i can use the electrical pump. The Airtex pump that I purchase a long time ago had positive and negative leads. I set my power to be iniitally on the positive lead on the pump and the negative lead to the ground. My car is positive grnd. It would not work, just switch ed the leads to be opposite and the pump works perfectly. Is your pump a positive grd pump or a negative grd pump. Rich Hartung Desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
Faulkner Posted March 31, 2021 Report Share Posted March 31, 2021 12 minutes ago, desoto1939 said: Is your pump a positive grd pump or a negative grd pump. Rich, as Ken points out above - my particular pump is agnostic with regard to polarity. It will work regardless of which lead is grounded. I intend to test this (by holding the leads to the battery, then swapping them), but I can believe it. Quote Link to comment Share on other sites More sharing options...
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