1983
1983
why am I loosing power to injectors when engine warms up?
starts and runs fine then sudden loss of power to injectors, then will not start
until cooled down?
starts and runs fine then sudden loss of power to injectors, then will not start
until cooled down?
Re: 1983
Are you certain its power to the injectors and not loss of spark?
The pick up in the distributor can fail in a way that it works fine cold, but fails when the engine warms up. Too a lot of trouble shooting to figure that one out.
The pick up in the distributor can fail in a way that it works fine cold, but fails when the engine warms up. Too a lot of trouble shooting to figure that one out.
Andy Jossy
Medford, Oregon
68 124 Coupe
72 128 Autocross car
82 124 Spider
86 X 1/9
88 Yugo
14 500e
Medford, Oregon
68 124 Coupe
72 128 Autocross car
82 124 Spider
86 X 1/9
88 Yugo
14 500e
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Re: 1983
Referring to the Fiat Manual: Spider 2000 Electrical Diagnostic Manual 1980-1981
Power to the fuel injectors comes from the dual relay. If you are loosing 12 volts to the injector connectors I would check for 12 volts at pin 88e of the dual relay.
The ignition pick up and ignition control module can cause the injectors not to fire. They provide a Tach signal to the ECU. The ECU then with other inputs determines how long the injectors open. The injectors should have 12 volts on their connector as long as the dual relay is activated. The ECU activates all the injectors at the same instant by supplying the momentary ground to complete the circuit.
Power to the fuel injectors comes from the dual relay. If you are loosing 12 volts to the injector connectors I would check for 12 volts at pin 88e of the dual relay.
The ignition pick up and ignition control module can cause the injectors not to fire. They provide a Tach signal to the ECU. The ECU then with other inputs determines how long the injectors open. The injectors should have 12 volts on their connector as long as the dual relay is activated. The ECU activates all the injectors at the same instant by supplying the momentary ground to complete the circuit.
Re: 1983
Thanks for the input, I have have changed the coil and pick up and magnet with spares
still the same, replaced temp sensor ,and battery is good lots of power at coil, I don't have spare injector
relay to try, but if the relay is bad why does it quit only when engine warms up, I know there is fuel and spark
but when it dies its only the power to injectors,I have checked with node light and they are dead until it gets cold
then it starts perfect runs great, all the grounds are solid on intake when its running all the injectors are clicking
even tried spare E C U same, think its a dead short in wiring harness ???
still the same, replaced temp sensor ,and battery is good lots of power at coil, I don't have spare injector
relay to try, but if the relay is bad why does it quit only when engine warms up, I know there is fuel and spark
but when it dies its only the power to injectors,I have checked with node light and they are dead until it gets cold
then it starts perfect runs great, all the grounds are solid on intake when its running all the injectors are clicking
even tried spare E C U same, think its a dead short in wiring harness ???
- rridge
- tremila club
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Re: 1983
The ignition switching module under the coil pack is the usual suspect when a hot FI engine stops running. But you say you have spark. I too would suspect a high resistance contact somewhere in the double relay or a connector in the circuit from ignition switch to double relay. If the FI fuse in the fuse holder under the ignition switch is original I would replace it just on age.
Why does a poor contact fail only when hot? The resistance across a dirty or corroded metal converts some the electrical flow to heat and heat raises resistance even further. When resistance is high enough current flow stops until the contacts cool and some conduction returns.
The double relay one of the known weak points in the FI system. It doesn't help that it sits in close proximity to the leak prone heater valve. If you don't have a known good spare and can't borrow one, buy a used one, test it immediately and keep it in the glovebox.
Is there any chance that you might have disturbed the two black ground wires that attach to the intake plenum and provide the ground paths for the FI system? They should be connected by ring spades under two the last two plenum bolts toward the firewall.
Why does a poor contact fail only when hot? The resistance across a dirty or corroded metal converts some the electrical flow to heat and heat raises resistance even further. When resistance is high enough current flow stops until the contacts cool and some conduction returns.
The double relay one of the known weak points in the FI system. It doesn't help that it sits in close proximity to the leak prone heater valve. If you don't have a known good spare and can't borrow one, buy a used one, test it immediately and keep it in the glovebox.
Is there any chance that you might have disturbed the two black ground wires that attach to the intake plenum and provide the ground paths for the FI system? They should be connected by ring spades under two the last two plenum bolts toward the firewall.
Richard
'81 Turbo Spider
Rockville, MD
'81 Turbo Spider
Rockville, MD
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Re: 1983
the Node light needs both the power from the dual relay and the ground from the ECU to light. Have you measured voltage with a vltmeter at the injector connector with the ignition switch on and the AFM flap open??,I have checked with node light and they are dead until it gets cold
Re: 1983
Noid

1970 238 Camper OHV
1974 124 Wagon TC
1974 124 Special TC
1975 124 Sport Coupe
1976 124 Sport Spider (The Racer)
1981 Spider 2000 (The Resurrected)
1985 Pininfarina Azzurra
2017 124 Spider Abarth Elaborazione
1974 124 Wagon TC
1974 124 Special TC
1975 124 Sport Coupe
1976 124 Sport Spider (The Racer)
1981 Spider 2000 (The Resurrected)
1985 Pininfarina Azzurra
2017 124 Spider Abarth Elaborazione
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- Joined: Sun Jan 24, 2016 9:36 pm
- Last Name: Laborde
- First Name: Dave
Re: 1983
I never could spell or proff read. 

Re: 1983
Thanks again for all the help electrics are not my strong area, if I understand the dual relay for the fuel system may be bad,
I thought if it was working it was ok, Can it fail when it gets hot and work ok when it cools off?
I took it out last night and it does look original. I see all the white wires on the one plug look the same as the wires to the injectors is this correct?
I thought if it was working it was ok, Can it fail when it gets hot and work ok when it cools off?
I took it out last night and it does look original. I see all the white wires on the one plug look the same as the wires to the injectors is this correct?
- rridge
- tremila club
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- First Name: richard
Double relay failure modes
Yes, the soldered connections between components and the circuit board crack and separate with age and the continuity of the circuits becomes fragile. Cold start, hot failure is a common way they fail. Park twenty FI Fiats on a large lot for a group photo and after sitting for twenty minutes odds are pretty good that one of them will not start. Odds are even better that at least two other owners will rush over with their spare double relays in hand. Been there, seen it, got the photo.Can it fail when it gets hot and work ok when it cools off?
Richard
'81 Turbo Spider
Rockville, MD
'81 Turbo Spider
Rockville, MD
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