Question of FD operation
 

Hello, I have some questions on the Fuel Distributor (FD)

Preliminary facts:

1) I know that the air sensor plate has an electrical connection so that the fuel pump does not come on until the sensor plate is lifted slightly.

2) I also know that if you disconnect this connector, the pump will come on when the key is in the run position.

3) My old FD would not output any fuel to the injectors unless the plate was slightly lifted (regardless of whether the fuel pump was on or off.)

What I did:

I replaced my old FD with a Euro one with steel lines and a different WUR. I wanted to prime the WUR and later the injectors.

I disconnected the electrical switch to the air sensor plate and turned the key to the run position.

What happened:
The fuel pump came on.
Fuel started flowing through the FD and the WUR (as expected).
After a few seconds, I heard fuel coming out of the injectors even though I did not lift the sensor plate.

My conclusion:
Based on my old FD, fuel should have gone through the WUR but not the injectors unless I lifted the plate.

Questions:
1) Should I try turning the mixture adjustment screw to lean it in the hopes that it shuts off?

2) The new FD had an air mass flow sensor that looks similar but had a different number than the old air mass flow sensor (0438-120-070 for the old vs 0438-120-143 for the new Euro one). Can it be that the Euro mass flow sensor is internally slightly different and I need to replace the old one with the Euro one as well?

Thanks

Have you adjusted the sensor plate height? It sounds like it's too high. The fuel pump should come on as the plate is lifted from engine vacuum during cranking and normal running. It should not be injecting fuel with just the key in the on position.

No, I haven't adjusted the sensor plate height. It was exactly as it was before. The only difference was that I put the new FD on the old air mass flow sensor.

I can tell you that at rest, and with the key on it's not supposed to be injecting fuel.

OK, problem solved.

First I tried my own suggestion #2. I went through the trouble of replacing the air mass flow sensor to the Euro one that came with the FD. I did not connect the injectors so that I could monitor any fuel flow coming from the FD. Fuel still came out to the injectors when the plate was undisturbed.

Then I tried suggestion #1 (should have done this first). I turned the fuel adjustment screw to lean the mixture until it stopped flowing. Purged the system, started it up then adjusted the AF ratio with the LM-2.

Thanks all