Replaced Fuel Pump, Replacement Pump Run Backwards Options

[jrrobertson]

The fuel pump (0580 463 009) on my 71 quit working. Even with power connected directly to the pump it did not work. I replaced it with a spare pump (0580 463 005) I had. This one only builds pressure if I switch the positive and negative leads. It will run when connected normally but it will run backwards and will push fuel down the return line. Anyone have any ideas as to why this is? The car runs OK with the wires switched.

The car has the original D-jet fuel injection system.

[wonkipop]

The fuel pump (0580 463 009) on my 71 quit working. Even with power connected directly to the pump it did not work. I replaced it with a spare pump (0580 463 005) I had. This one only builds pressure if I switch the positive and negative leads. It will run when connected normally but it will run backwards and will push fuel down the return line. Anyone have any ideas as to why this is? The car runs OK with the wires switched.

The car has the original D-jet fuel injection system.

009 is the pump that superceded the 005.
were at least fitted to 74 1.8s.
009 slightly more compact design than a 005.
both are near identical and both are for the 914.
i've never fully gotten to the bottom of it - ie as to whether the 009 is specifically for the L jets, some literature i have suggests its just a bosch supersede chronologically, jeff bowlsby has other material that says the 005 is the only pump on 914s until the change in 75.

point being - the 005 should have run the same as the 009.

to be pumping out the return line is definitely not right.
that return line which is the last of the three ports is in fact the pressure relief line.
it means your pump is developing overpressure and relieving.
and the pressure line to the fuel circuit, the central port is blocked somehow.
there is a little sliding pin in there with a spring. its pretty simple how it works.

the normal return line is via the injector circuit after the fuel pressure regulator.
that one out of the fuel pump is overpressure relief and has a t into the return.

not quite sure what is happening with your pumps.
but it sounds like someone has had one of them apart and has not reassembled it correctly.

whatever went on it with it, they both should have hooked up the same.

i'm not sure that is such a great set up to be having the fuel pump running out of the "return" line from the pump. if i am not mistaken there is no way for it to pressure relieve. i could be wrong about that but i believe that would be the case. its possible it might be able to relieve back down the supply line from the tank but it would not be natural for it to do that as its contrary to the way roller cell pumps work.

i've rebuilt both the 009 off my car and a 005 that came off a D jet SAAB which also had them fitted. i've seen inside both pumps and tested their flow rates and pressure delivery. its the same pump essentially.