injectors not firing

[david2335]

1980 fiat 2000 -Car will start right up after sitting all night after car warms up and you turn the car off , the injector will not fire.

[vandor]

Are you sure the injectors don't fire? Have you checked with a noid light?
When this happens, take the airflow boot off the airflow meter and move the flap with the ignition on. Do you hear the fuel pump come on?

[narfire]

Are the two grounds on the intake plenum in good shape?
As Csaba mentioned, how do you know for sure it is the injectors? You've taken an injector out and test flowed into a can?
The rubber boot is sound,no tears or rips. How about the aux air valve ? when cold it should have a notable hole when you look through and when it warms up the hole gets smaller to almost tightly closed.

[david2335]

Are you sure the injectors don't fire? Have you checked with a noid light?
When this happens, take the airflow boot off the airflow meter and move the flap with the ignition on. Do you hear the fuel pump come on?

yes checked with a noid light the fuel pump is runing

[david2335]

Are you sure the injectors don't fire? Have you checked with a noid light?
When this happens, take the airflow boot off the airflow meter and move the flap with the ignition on. Do you hear the fuel pump come on?

i checked with noid light and you can hear the fuel pump runing after siting for 2 hours if will fire right up.

[rlux4]

You're saying that you checked your injectors with a noid light, are you saying it showed that they weren't pulsing? If they're not pulsing it wouldn't start up after two hours. It's got to be either one or the other, unless you have an intermittent problem, which is usually an electrical issue, most probably ground ing related.
As Narfire suggested, check the two ground wires on the rear/outboard of the intake plenum, these are the injector grounding points.
Ron

[vandor]

Hm, it's strange that the fuel pump comes on, but the injectors don't fire. Almost like one side of the double relay is working, but the other side is not. Is there anyone you could borrow a know good double relay from, and swap it in to check?

It's a long shot, but make sure the connection on the negative side of the coil that goes to the ECU is good and tight.

[david2335]

Hm, it's strange that the fuel pump comes on, but the injectors don't fire. Almost like one side of the double relay is working, but the other side is not. Is there anyone you could borrow a know good double relay from, and swap it in to check?

It's a long shot, but make sure the connection on the negative side of the coil that goes to the ECU is good and tight.

it was the cnnection to the cold start valve i had it connected to the throtle plate switch.Thanks for the help