924Board.org

The 4th paragraph of Fiat22's link gives the location of the ground. Check it or not it's your choice.

The negative wire should go to ground. Use an ohm tester to make sure it isn't shorted.

Check the ground wire from the external pump to the body. If that's OK it is probably the pump itself.

Is the valve on the correct side of the gauge?

Have you checked the inside of the distributor cap for signs of cracks or carbon arcing?

The relief valve could have been leaking but a defective (low control pressure) WUR would have compensated to a point. If the new WUR has raised the control pressure, a leaking relief valve would caus ...

The relief valve is in the fuel distributor. It is removed by unscrewing the brass hex bolt on the side. When you remove it, check the condition of the o rings.

Was the new pump made specifically f ...

Your problem may be caused by low system pressure. This can be caused by a defective/clogged relief valve, incorrect (low pressure) or defective fuel pump, partially clogged fuel filter or a plugged p ...

The early US 928's used the steel bodied FD. The pictured one is like the later model Mercedes V-8 distributors that had adjustments for each cylinder and were aluminum bodied. BTW Mercedes used the C ...

What is your voltage between 15 and ground at the coil when cranking?

Dennis

Please keep in mind that a larger venturi will result in slower air movement past the air sensor plate and may cause the engine to run lean.

Dennis

There is a vacuum line going to the computer. While there you may want to check for corrosion on the electrical connections.

Dennis

Have you checked the vacuum line going to the computer under the center console?

Dennis

Think you are right. Forgot that you had an 81 931.

Dennis

If your distributor has 2 vacuum lines going to the advance, you may want to recheck the routing to make sure the lines aren't reversed.

Dennis