Fuel Injector Cooling Fan not working

RicB

RicB

True Classic
I think the thing shown below in the top left of the rear trunk is the Fuel Injector cooling fan which usually continues to run after the engine is turned off? After having my bumper holes welded up which required the taillights to be removed for painting, I found that the black ground wire was not connected. I reconnected it to one of the taillight studs and since then, it has never turned on. I checked the fuse (socket B according to the manual) and it is OK. Perhaps it is a different fuse? Thanks.



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Is the tail light stud actually grounded?

Ohm it out, I found that my tail light studs had no connection to ground.
 
Stud ground explained

The taillight stud ground method has long been a problem for Fiats. Spiders use this for grounding the fuel pump, and it can overheat and pull the stud right out of the light housing. Same applies here.

The stud is only grounded if the nut and/or washer holding it on touch bare metal. If you think about the tension required for this, the strength of plastic, the opportunity for rust and corrosion, paint getting in the way, you can imagine why it can be a problem. Might be best to relocate the grounds to a separate ground screw. A serrated or "star" washer under the ring terminal closest to the body metal is a good idea if yours is missing.
 
And...

Check the switch, it's screwed into an aluminum block bolted to the head near the injectors and the pulley end:
IMG_8041-1.jpg


Unplug the harness and plug the wires from the car side together; the fan should run if all else is good. There's also a relay for this in the spare tire area.
 
I was chasing a taillight grounding problem a few weeks ago..

budgetzagato said:
The taillight stud ground method has long been a problem for Fiats. Spiders use this for grounding the fuel pump, and it can overheat and pull the stud right out of the light housing. Same applies here.

The stud is only grounded if the nut and/or washer holding it on touch bare metal. If you think about the tension required for this, the strength of plastic, the opportunity for rust and corrosion, paint getting in the way, you can imagine why it can be a problem. Might be best to relocate the grounds to a separate ground screw. A serrated or "star" washer under the ring terminal closest to the body metal is a good idea if yours is missing.
Click to expand...

And found that my taillights ground to a stud/star washer that comes out of the inner trunk liner - the same piece of sheet metal that the taillight studs pass through. These studs appear to be specifically for grounding, and point towards each other (in other words, they lie at a 90 degree angle to the taillight studs).

My problem was simply a loose nut on the grounding stud.

Anyhow, it would probably be a good idea to run a longer wire over to this dedicated ground, than to mess with the taillight studs. Notice that Fiat did not use them for grounding the taillights - at least, not on my 87. Not sure about earlier years.

Pete
 
..the ground for the fan is supposed to go on the stud/bolt that secures the fan mounting bracket on the rear panel. Move it to there from the tail light, and hopefully that will be the end of it.
 
Looks like the switch is bad?

Connected the ground to the mounting bracket as suggested and then tested the switch as suggested. Fan works. I can't remember, does the fan only come on at a certain temperature? Or always at normal operating temp? Don't want to go and replace it when it turns out that my engine hasn't been getting hot enough to trigger the fan to come on.
 
Similar to a radiator fan switch...

It comes on at one temp and turns off at a lower one. It unscrews from the block/sink and should have the temps (likely in celcius) on the edge of the hex. You can use a VOM to test for continuity as you warm it in a saucepan of water on the stove if you like.

Mine comes on occasionally after a long drive in very nice weather, runs for a minute or so, shuts off.
 
It only comes on when the key is turned off.

Mine comes on regularly in the current ambient temps, but turns off pretty quickly.
 
It only comes on when the key is turned off.
Click to expand...

It is actually connected to the sender for the oil pressure warning light, not the ignition switch. So, it will turn on any time the oil pressure is low and the temperature in the engine bay is high.
 
ng_randolph said:
It is actually connected to the sender for the oil pressure warning light, not the ignition switch. So, it will turn on any time the oil pressure is low and the temperature in the engine bay is high.
Click to expand...

Has that ever happened for you? I understood that the circuit relay uses the OP switch as a ground, which I understood to only happen when no OP is present... The thermal switch controls the power to the relay for the fan. The FI wiring diagram doesn't actually show the ground side of the circuit...

pos 24, 25, 26 in the diagram..

bertone_7.png
 
I have never had the fan come on while the engine is running, but if the injector fan is still running when I try to start the car, it stays running until the engine starts and the oil pressure light goes out.

I agree that the wiring diagrams are a bit cryptic here, particularly since it appears the oil pressure sender also is used is also used for a "lamp test" function for the 30k mile warning light for the O2 sensor.
 
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