Fiat Fuel Injection Diagnosis Tech information

[Sydmn]

I have a 1981 Spider 2000 and I'm using the subject manual to find out why the injectors are not firing. On P3, item 4, I checked for voltage and found zero, so I went to through item 13 to 18. Item 18 is a check to ground and the test light should come on with flickering intensity while cranking. When I go to operate the starter the test light comes on when the key is in P2 and stays on but does flicker while cranking. Is the light on in P2 any thing to worry about or can I consider this a successful test?

[DRUMMOND]

Hi Sydmn

Make sure you check all of your grounds first. most of the problems in FI are ground related, especially the injectors not firing.
Check your ignition coil connections and the valve cover ground bolts (2) for the FI computer.

I believe the test is an ok!

[Sydmn]

I have cleaned the two grounds attached to the rear of the plenum, these you tell me go to the ECU.
I also have a ground wire attached to the rear of the RH camshaft housing. Right now the other end of this wire is attached to one of the two tapped holes in the coil heat sink or cradle. Is this correct?

[DRUMMOND]

I don't believe that ground is normal? You might also want to check your main ground wire under the engine on the left side. Looks like there might have been a ground problem in the past and the solution might have been this xtra wire, to check your grounds are actually working you should use a digital multi meter, connect each end of the ground wire to check for connectivity and resistance, lower the better.
Did you also check that you have 12v to each injector?
You can also get a pigtail fuel injector connector and connect a 12 volt source through a momentary switch to the injector to see if it clicks .

Did you check your FI double relay?
Did you check your AFM?
Did you check for proper coil connections?

[RRoller123]

That wire is normal, it was added to avoid a ground isolation problem.

[Sydmn]

I don't believe that ground is normal? You might also want to check your main ground wire under the engine on the left side. Looks like there might have been a ground problem in the past and the solution might have been this xtra wire, to check your grounds are actually working you should use a digital multi meter, connect each end of the ground wire to check for connectivity and resistance, lower the better.
Did you also check that you have 12v to each injector?
You can also get a pigtail fuel injector connector and connect a 12 volt source through a momentary switch to the injector to see if it clicks .

Did you check your FI double relay?
Did you check your AFM?
Did you check for proper coil connections?

Thanks for the reply.
I have been checking the injection system using the Fiat Fuel Injection Manual and it says there is no voltage across the injector (I was testing #1 injector)
All ground wires have been checked and cleaned.
The FI double relay iis checked when going through the Fiat manual.
My coil connections are: U Pos....Pink, Ignition.
Red, control module.
Black, Radio caoacitor.
D Neg....Black, control module.
Brown/white, ECU, Tach
Yellow ?
Could you confirm the above coil connections are correct.
The Fiat Injector manual ends up saying to replace the ECU!

[Sydmn]

I forgot to add that both sides of #1 injector have 12v with the ign on.

[spider2081]

I forgot to add that both sides of #1 injector have 12v with the ign on.

I think this is correct. Power to the injectors 1 & 2 comes from the double relay pin 88e. Power to injectors 3 & 4 comes from double relay pin 88b. The momentary ground that triggers the injector comes from the ECU. It is only present for milli seconds. The rest of the time the output of the ECU is battery voltage. I'm pretty sure if you unplug the ECU and the injectors, the connectors will only have power on one of their pins.