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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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 Posted: Fri Apr 10, 2015 12:47 am Post subject: |
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On some models, isn't there an input to the fuel pump or ignition relay from a switch on the side of the fuel distributor to indicate when the flapper valve has moved appropriately?
I know it was on my 79....
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Fri Apr 10, 2015 5:12 am Post subject: |
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| fiat22turbo wrote: | On some models, isn't there an input to the fuel pump or ignition relay from a switch on the side of the fuel distributor to indicate when the flapper valve has moved appropriately?
I know it was on my 79.... |
This is correct.
The fuel pump activates when the sensor plate moves. Theres no connection between coil or ignition function and the fuel pump operation. |
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brian19600
Joined: 28 Oct 2013
Posts: 375
Location: NJ/CT
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Muz924
Joined: 21 Jul 2010
Posts: 137
Location: Melbourne Australia
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| Posted: Fri Apr 10, 2015 12:02 pm Post subject: |
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I thought i was going nuts.... I just checked my Haynes Manual.
Page 258 (79 & 80 models) clearly shows a wire from (negative) terminal #1 of the coil running to terminal #1 of the fuel pump relay.
(This is the same connection that runs to the tacho).
My understanding is the fuel pump relay needs a signal from the coil terminal #1 & #15 (ignition switch) for it activate.
This is exactly how my car is wired.
Cheers,
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1978 924 RoW 5-Speed (Current Project)
1980 924 RoW 5-Speed (Donor Car)
1985 Alfa Romeo Alfetta GTV 2.0 (Previous Project Car) |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Fri Apr 10, 2015 12:31 pm Post subject: |
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| Muz924 wrote: | I thought i was going nuts.... I just checked my Haynes Manual.
Page 258 (79 & 80 models) clearly shows a wire from (negative) terminal #1 of the coil running to terminal #1 of the fuel pump relay.
(This is the same connection that runs to the tacho).
My understanding is the fuel pump relay needs a signal from the coil terminal #1 & #15 (ignition switch) for it activate.
This is exactly how my car is wired.
Cheers, |
Is this for your '78 or '80?
The coil has no control over the fuel relay. The wire you're talking about for the '79/'80 is from the transistor unit. Wire "15" is a trigger from the transistor unit to the relay & to fire the coil, not from the coil to the relay.
Coil function has no effect on the relay function. |
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Muz924
Joined: 21 Jul 2010
Posts: 137
Location: Melbourne Australia
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| Posted: Fri Apr 10, 2015 1:41 pm Post subject: |
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The coil is 'triggered' from the module terminal #16 to coil #1.
The wire from coil #1 relays that signal to the fuel pump & tacho.
Terminal #15 on the coil is (positive) 12v supply from module & starter motor. (both wires being resistance wires).
Cheers,
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1978 924 RoW 5-Speed (Current Project)
1980 924 RoW 5-Speed (Donor Car)
1985 Alfa Romeo Alfetta GTV 2.0 (Previous Project Car) |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Fri Apr 10, 2015 2:16 pm Post subject: |
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| Muz924 wrote: | The coil is 'triggered' from the module terminal #16 to coil #1.
The wire from coil #1 relays that signal to the fuel pump & tacho.
Terminal #15 on the coil is (positive) 12v supply from module & starter motor. (both wires being resistance wires).
Cheers, |
Terminal 16 is what I was talking about. I mistook the "1.5" wire size for "15", I was looking at a copied diagram (oops). That's why I said wire not terminal. Anyway, the black wire (what i thought said 15) from the transistor terminal 16 is on the same coil terminal (1) as the green fuel pump relay wire, terminal 1 on the relay.
The signal goes from the transistor to the coil & relay, not from the coil to the relay. The coil activates from a ground pulse from the transistor unit. Its the same pulse that operates the solid state circuit in the relay and also triggers the tach. |
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Muz924
Joined: 21 Jul 2010
Posts: 137
Location: Melbourne Australia
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| Posted: Fri Apr 10, 2015 4:47 pm Post subject: |
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So....... do we agree that the fuel pump relay needs a signal/pulse from the coil as well as voltage from ignition switch to operate?
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1978 924 RoW 5-Speed (Current Project)
1980 924 RoW 5-Speed (Donor Car)
1985 Alfa Romeo Alfetta GTV 2.0 (Previous Project Car) |
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brian19600
Joined: 28 Oct 2013
Posts: 375
Location: NJ/CT
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| Posted: Fri Apr 10, 2015 8:34 pm Post subject: |
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I haven't looked at any wiring diagrams, but on my 1978 with relay 477906059, my coil is currently disconnected and there is no distributor in it. With the ignition switch on, the fuel pump will operate when I lift the plate.
My understanding is that this is the correct operation for this year car.
My understanding is also that 79-82(?) no longer use the sensor plate, but use a signal from the distributor to let the fuel pump know the engine is cranking/running.
According to the PET: 477906059 fuel pump relay 76-78
433906059 fuel pump relay 79-
My understanding is that these relays are pinned differently and cannot be physically swapped.
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78 924 |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Fri Apr 10, 2015 9:42 pm Post subject: |
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| Muz924 wrote: | | So....... do we agree that the fuel pump relay needs a signal/pulse from the coil as well as voltage from ignition switch to operate? |
No, I don't think so, I'm not sure what you mean by "from the coil". The pulse comes from the transistor unit, not the coil itself. The connection is at the coil though. The transistor signal and the wire going to the relay are on the same contact of the coil but the coil doesn't send the signal.
This may be a case of "we're saying the same thing a different way".
So if you're saying the coil is responsible for the pulse to the relay, we disagree.
If you're saying the pulse goes from the transistor to the coil terminal & then from that terminal (connection) the transistor signal is sent to the relay, we agree.
The pulse signal comes from the pick up (either from the distributor or flywheel depending on the car), not the coil. The relay needs a signal that the engine is spinning, not that spark is being made. If you leave the black & green wire connected to the spades and remove the coil, you will see the fuel pump will still run when cranked.
Your '78 shouldn't even have this system, it must have been a mid year change. |
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Muz924
Joined: 21 Jul 2010
Posts: 137
Location: Melbourne Australia
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| Posted: Sat Apr 11, 2015 10:01 am Post subject: |
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| Quote: | | If you're saying the pulse goes from the transistor to the coil terminal & then from that terminal (connection) the transistor signal is sent to the relay, we agree. |
Then we agree!
I say "from the coil" because that's where the wire physically comes from.
The intent of all this is that the fuel pump only operates when it has 12v from ignition and a pulse signal that it (physically) gets from the (-) terminal of the coil (ie: the engine is turning).
I think you thought I was saying the pulse signal was being generated by the coil??
Anyway, going back to where this all started in reply to Ideola's reply... the spark plugs dont foul with fuel because the fuel pump doesn't run because of no spark/no pulse signal at coil & ignition module....by removing 1 spark plug it then starts straight away (on three cylinders).
This would tell me its the module causing the problem (which i haven't replaced as they very rare) however replacing the coil alone sometimes helps.
I think the problem is "upstream" of the (-) terminal of coil being in order:
-wiring (from coil to module)
-module itself
-wiring (insulated from module to the distributor).
-distributor itself.
Which of these would not work only when it gets cold ????
(might be combination of more than one).
Cheers & thanks for trying to help..and suggestions are appreciated. 
_________________
1978 924 RoW 5-Speed (Current Project)
1980 924 RoW 5-Speed (Donor Car)
1985 Alfa Romeo Alfetta GTV 2.0 (Previous Project Car) |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Sat Apr 11, 2015 10:02 am Post subject: |
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| Muz924 wrote: | I think the problem is "upstream" of the (-) terminal of coil being in order:
-wiring (from coil to module)
-module itself
-wiring (insulated from module to the distributor).
-distributor itself. |
Exactly.
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erstwhile owner of just about every 924 variant ever made |
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jason c
Joined: 13 Jan 2014
Posts: 1018
Location: Nwi
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| Posted: Sat Apr 11, 2015 11:22 am Post subject: |
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| Muz924 wrote: | | I think you thought I was saying the pulse signal was being generated by the coil?? |
Yes, exactly. 1)because of wording. 2)because you said (or implied) changing the coil was the fix.
So, moving on.....
I don't remember if any of this has been covered yet.
Have you checked coil resistance when its running good & bad?
Have you checked resistance of the spark plug wire before & after changing them?
Check resistance of the wiring.
Grounds grounds grounds.
As for cold, wiring looses conductivity when hot, not cold. Moisture tends to build when temps go from hot to cold (ie your lawn covered in dew in the morning).
Do you park on concrete or ground?
The transistor units are known to be sketchy & fail so it would be a good idea to find a spare if you plan on keeping the car. |
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924 FAQ (Technical)
