1981 FI Spider- No start

[jcuje]

Hi all,

I know this topic has been brought up before, but I cant seem to figure out the problem with the info provided. I've got an 1981 Fiat that I had running and doing well. After it sat in a dry, heated garage for a week it started right up, I backed it out and it stalled and wouldnt start again. Coil has power, fuel injectors are getting power, i have a new fuel injector relay, fuel pump has power but when i pulled a fuel injector out, I get NO SPRAY. I have fuel past my pressure regulator so now I'm stumped. Car will want to run if I spray carb cleaner in the intake at throttle...Please help.
Thanks,
Jeff

[So Cal Mark]

besides power to the injectors, you need a ground which is provided through the ecu. Since it ran before, I'd check the intake boot to make sure it's connected and not split open on the bottom. Also check the connections at the coil. The ecu gets a pulse from the - side of the coil and won't fire the injectors without that signal

[jcuje]

besides power to the injectors, you need a ground which is provided through the ecu. Since it ran before, I'd check the intake boot to make sure it's connected and not split open on the bottom. Also check the connections at the coil. The ecu gets a pulse from the - side of the coil and won't fire the injectors without that signal

Thanks mark....no split in intake boot. Coil - good..... one thing to mention is that if i prop the door open to the AFM it starts and stays running but if you hit the gas, it stalls out...Correction...if i play with it i can get it to run even when gunning the throttle however second i close the AFM door, it stalls.

[vandor]

First thing I would look for is a large vacuum leak - intake boot, booster hose, aux air valve hose.

[rlux4]

Check the function and setting of your throttle position sensor. With the flap closed it should at least idle, so you're loosing pulse signal to the injectors. It may also be a bad spot on the wiper track in the AFM, which has lost continuity. If this is the case you could try to move the wiper arm higher or lower on its mounting shaft which will make the contact on the track a different arc.
The procedure is documented in this article;
http://the944.com/afm.htm
Ron

[jcuje]

will try again... just curious....I dont think its a vac leak from previous visual inspection but why would that cause the injectors to not spray?

[So Cal Mark]

a warped door in the afm will allow air to bypass the door

[vandor]

will try again... just curious....I dont think its a vac leak from previous visual inspection but why would that cause the injectors to not spray?

Because the AFM door never opens, thus the fuel pump does not turn on.

[vandor]

Check the function and setting of your throttle position sensor. ...

That won't keep a car from starting, tho.

[jcuje]

Hi all- Just an update on the no-start condition.

Fuel pump is new and working.
Coil is working and strong spark.
I swapped air flow meter with a good car- condition persists.
No leak in plenum.
New Pickup coil is in.
I have power to injectors and ground is present and clean.


What else could cause the injectors not to pulse? Crank shaft sensor?

Thanks for your help so far!
Jeff

[So Cal Mark]

no crank sensor on your car. The ecu receives a signal from the - side of the coil to indicate engine cranking

[jcuje]

no crank sensor on your car. The ecu receives a signal from the - side of the coil to indicate engine cranking

Thanks Mark.....
Thats what I figured.....Any thoughts on where to go next? Coolant temp sensor?

[rlux4]

Not the temp sensor. The ECU will read the resistance it's sending to adjust mixture for engine temp. You'll need to check that the ECU is getting the signal from the coil. Check continuity on the brown with white stripe wire attached to the "-" side of coil and the pin in the ECU pigtail at the #1 position. Then check for good ground continuity at connectors 16&17. If you have continuity it may be a bad ECU. I have a bad one in the garage that won't send pulse signal to the injectors.
Ron

[GeorgeT]

Check the Double Relay.

[rlux4]

He said he had power at the injectors. With power at the injectors and the fuel pump running the dual relay is working. Power for the injectors comes from the dual relay, the pulse is controlled on the ground side of the circuit by the ECU responding to the coil firing.
Ron