81 FI Harness

[Cal124turbo81]

Hi,
The issue with my car is that it starts but then shuts off and gas leaks at high pressure from the cold intake. What I have ruled out: 1. The ECU 2. Air Intake
My mechanic thinks that the wire harness to the injectors is not working. We need to test for shorts still. Has anyone experienced this issue or heard about it? If so, any ideas on how to fix it?
Thanks!

[So Cal Mark]

it would be very simple to check the harness for a short to ground, but I'm not clear what you mean by "fuel leaks from the cold intake".

[Cal124turbo81]

Hi,
Let me see if I can be more clear. I turn the car on it dies shortly there after. After it dies gas leaks from where the hose connects to the cold start connection. It seems as if there is too much pressure in the line and the fuel finds a way to get out.

[Cal124turbo81]

Thaks SoCal Mark!

[majicwrench]

Sounds like you need a new mechanic. If leaking from conneciton at CS injector, banjo bolt is loose (careful here) or needs new copper washers. This is super simple.
Why would he think harness "not working"?
Keith

[Cal124turbo81]

Thanks Majicwrench! Well got the fuel leak figures out. Now, we have that there is no power going into the injectors. Swaped out a CPU that we know is working and no power to the injectors still. It is beginning to look like an electrical issue.
I will keep you posted.

[spider2081]

I believe power for the injectors comes from the fuel injection relay set located with the other relays under the glove box. Injector power should be present in the start and run position of the ignition switch. The ECU supplies the momentary ground that energizes the injectors.
Power to the relay set for the injectors is the brown wire from the battery positive terminal. It is on terminal 88z of the relay. When the ignition switch is in the start or run positions power is applied to terminal 88c activating the control portion of the relay set. This connects terminal 88z to terminal 88e and 88b and 88a of the relay. 88b powers injectors 3 and 4. 88e powers injectors 1 and 2. 88a powers the fuel pump switch in the air flow sensor.
It would be very strange to have power to the fuel pump and not to the injectors as the same part of the relay set is common to both the pump and injectors.
If you are sure you have no voltage at the injectors (with ignition switch in "start or run") and your fuel pump is working I think a previous owner has modified the cars wiring.
You need to get a wire diagram of the fuel injection system.

[wizard124]

I dont have my manuals with me,,,,,,working from memory.

If the coolant sensor fails (at coolant T in front of engine), or bad connection to ECU, wont this prevent the engine from running. Check simple first.

Coolant Temperature Sensor

The coolant sensor is tested on the ECU connector. Unplug the ECU and connect an ohmmeter between terminals 13 and ground (vehicle body). The meter should read:

Temperature (F) OHMs

14 7,000 to 12,000

68 2,000 to 3,000

176 250 to 400

If the reading is 0 or less replace the sensor. If the reading is infinity check the wires leading to the sensor for a break. If the wires are good, replace the sensor.

The coolant temperature sensor can cause the engine to stop running. If your fuel injected Spider is running nicely and suddenly stops, inspect the wires leading to this sensor. Bosch makes a replacement wire and connector set that will eliminate this issue (for the next 20-30 years, then it will become brittle and fail again!)

[Cal124turbo81]

Thanks for the info Spider 2081!!! I have not worked on it in the past few days but will pick up over the weekend. The only re-wiring that the previous owner did was to insert a "kill switch" for the fuel pump. But the fuel pump is running. Thanks to you now I have an idea of where I should be prodding. I will keep you posted.

[Cal124turbo81]

Thanks all.
@Wizard124: all has been checked and in working order

UPDATE: I have checked for electricity to the fuel injection relay. I took the relay off and used a meter to see what electricity I was getting. Of all the wires that connect to the relay, only the brown one had energy. In further inspection of the wiring I found a lot of burnt/crimped wires. Discovered that so far there is no energy to: 1. blinkers 2. headlights.
I also discovered wires that were not connected or just dangling, my guess is that they were part of the turbo system.

My question now is how do I go about replacing burnt wires? Is there any advice you may have as to how to rewire (besides looking at the wiring diagrams)?
Do you think that taking pictures of the wires and harnesses would help member tell me what they are for?

THANKS!!

[wizard124]

From my Fiat FI Manual......

"With the engine running and ignition switch released, current no longer flows from Terminal 50 (ignition switch) to energize the fuel pump relay. Current from the closed contacts of the power relay flows thru the closed contacts of the fuel pump switch in the air flow sensor to the fuel pump relay, keeping the relay energized."

Since your engine dies shortly after starting. It seems to me that the power and fuel pump relays are working properly. My take is, the fuel pump contact in the air flow sensor is not closing. This contact should close once air is pulled thru the air flow sensor during the starting process. If it does not, the fuel pump relay opens and the fuel pump stops.

The FI diagnostic manual under "Engine starts then stops" list these steps (summarized as follows):
1) Disconnect hose to Air Flow Sensor. Connect test light between 88d of relay and ground. Turn on ignition. Sensor flap closed = no light. Sensor flap open= light on.

2) If light does not come on. Connect test light to 86b of relay and ground. Sensor flap closed= no light. Sensor flap open= light.
a) If test light operates properly= replace relay set;
b) if test light does not operate properly= check wires then replace air flow sensor.

You may be able to clean or re-align the fuel pump contacts within the air flow sensor rather than replacing it.

The other diagnostic branch takes you to checking the coolant temperature resistance and its wires.

[Cal124turbo81]

Hello Everyone!
Thanks for the information provided thus far! It has been very helpful!
Here is the latest:
1. I replaced the dual relay with a known working one.
2. 12v coming in to the pink, brown and brown/white wires.
3. Checked the two ground connections on the air intake and they are grounded.
and still no power to the injectors.
My next step is to change the ECU and if that is not the issue I will run the following diagnosis: http://www.wcmotors.com/personal/Fiat%2 ... agnostics/

Ok I will update you all when I am done... probably saturday if not sooner.
Cheers,
Adolfo

[wizard124]

88a powers the fuel pump switch in the air flow sensor.
It would be very strange to have power to the fuel pump and not to the injectors as the same part of the relay set is common to both the pump and injectors.
If you are sure you have no voltage at the injectors (with ignition switch in "start or run") and your fuel pump is working I think a previous owner has modified the cars wiring.

From my Fiat FI Manual......

"With the engine running and ignition switch released, current no longer flows from Terminal 50 (ignition switch) to energize the fuel pump relay. Current from the closed contacts of the power relay flows thru the closed contacts of the fuel pump switch in the air flow sensor to the fuel pump relay, keeping the relay energized."

Since your engine dies shortly after starting. It seems to me that the power and fuel pump relays are working properly. My take is, the fuel pump contact in the air flow sensor is not closing. This contact should close once air is pulled thru the air flow sensor during the starting process. If it does not, the fuel pump relay opens and the fuel pump stops.

A more thorough discription:

Terminal 15 of the ignition switch stays hot in RUN and and Start (pink/black wire to relay connection 86c). This wire powers the power control relay in the relay set. When closed, this relay energizes the injectors and ECU. Since your engine starts, this power control relay is working.

Once the key is out of the Start position, terminal 50 is cold (red/black wire to terminal 86a). 50 powers the fuel pump relay and cold start circuit. With the engine running and air being sucked through the Air Flow Sensor, its closed switch now energizes the fuel pump relay. The same power control relay is still closed that powers the injectors and ECU.

Since you have now swapped the relay set, I'll try to convince you to do the diagnostics I supplied earlier. The black plastic cover of the AFS is stuck on with silicone and removes easily. Inside you will see the contacts that should close with the slightest movement of the flap. If the flap is stuck or the contacts worn or mis-aligned, the fuel pump does not run and the engine quits. Which sounds exactly like the problem you describe. If the PO has messed with the original wiring, then all bets are off. The diagnostics will tell you if this switch is working.

I am not making this stuff up I am giving you info from Fiat manuals that I own. Just trying to get you on your way

[Cal124turbo81]

I am ELATED to report that she is now running!!
I ran with this diagnosis: http://www.wcmotors.com/personal/Fiat%2 ... led-12.jpg
and I discovered that my wire on the number 1 of the ECU was not connected to the Coil.
Again thanks to all for your support!!!! Now to continue with the restoration of EVERYTHING else

Adolfo