Engine Only Running with Fuel Cut Off

[NickFerrell]

Been working on this 1980 fuel injected Spider with a friend. I was having a few issues (see http://www.fiatspider.com/f08/viewtopic.php?f=5&t=27493 ). Dropped the tank, flushed it, put it back with a new filter.
Now, it will only run at idle after the fuel has made it to the engine, but with the supply from the tank removed. If the line is left on, it can only run if it's revved to around 4,000 rpm. Otherwise it sputters and dies.
With the supply line removed, and fuel in the lines, it idles beautifully for 3-4 minutes, then starves and dies.
Also, when the supply is connected, it often turns over until it suddenly stops, and sounds like the starter quit. Especially with the pedal depressed.
I tried a supply from a gas can with identical results.

It seems obvious that it's dumping too much fuel in, right? Regulator bad? Thoughts?

[chrisfiat]

first check to see if the cold start injector is spraying continually, if so solve that problem first

[RRoller123]

Sounds like maybe the tank is developing a vacuum.

[wizard124]

Could your fuel lines be switched? The supply fits to the end of fuel manifold. The return fits to the bottom of pressure regulator.
I don't know how she runs with the supply disconnected, no pressure to the injectors.

[NickFerrell]

Could your fuel lines be switched? The supply fits to the end of fuel manifold. The return fits to the bottom of pressure regulator.
I don't know how she runs with the supply disconnected, no pressure to the injectors.

I removed the supply at the tank. My thoughts are that it's running on what's in the lines.

[spider2081]

The sensor in the cooling "T'" and its connector cause all sorts of crazy problems. If you have an ohm meter the troubleshooting guides give 3 resistance readings for the sensor, cold, medium, and hot.

Inspect the connector, clean it and after its reinstalled wiggle it around with engine running to see if its intermittent.