"popping"

[dphdo]

Greetings all. A couple of questions: 1. I have a '74 412 wagon, AFC fuel Inj. Isn't the fuel pump supposed to run for about 2 seconds or so when you turn the key to the #1 position (run - not start) to pre-pressurize the system? I've seen Vanagons do this, and it seems a former '74 412 variant did as well. Second Question: I'm getting a strange "popping" noise from cylinders 2 & 3. At Idle, these two cylinders aren't even firing, then as I rev it up, they engage, but with this LOUD noise. It isn't a backfire, just an explosion type noise. I've checked the valve adjustments, points, plugs, coil, and even the compression (120 pounds - a new rebuild). I checked the injectors while trying to start the car, and they sprayed evenly. Any thoughts? Tahnks, Dale

[ray greenwood]

Hmmm..are you sure they are not even firing at idle? Or are they not injecting at idle? Usually that sounds like dirty and bent connectors in the FI harness that make connection when the engine speeds up...or spark plug wires doing the same. Next thing...have you checked the firing order? wires on right...and have you checked that the injector part #'s are the same and not leaking? Ray

[richard411412]

Try checking the FI points in the bottom of the distributor. Also check the three prong connector that goes to them. You can hook up a continuity tester to the three terminals on the points and see if they are opening and closing normally. This is easier to do with the dist. out of the car. If it is the FI points, a new type 3 set is only about $25.