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Discussion Starter · #1 ·
Good afternoon all,

I picked up a relatively solid 86 GTV6 project a bit back and I'm finally getting around to messing with it. I bought the car as a non-runner with the description that it ran for the PO, then "sounded like it ran out of gas" and never got going again.

In my attempts to get it running I replaced number 5 and 8 fuses, the fuel pump with a new unit, and the combi relay on the firewall. The pump will run if jumped, and fuel will build pressure at the rail, but will not run if the relay is installed, nor will it run when opening the AFM flap manually. If the pump is jumped and rail pressure built, the engine will fire for a second then die (I'm assuming from the cold start injector). The fuel injectors also have no pulse nor 12V with ignition on.

There is no inertia switch or bypass anywhere that I have found, and I do not believe 1986 MY cars had them.

As it stands I'm somewhat stuck, as following the workshop manual only offers a combi relay replacement as a solution in this situation.

Any help would be greatly appreciated!
 

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Discussion Starter · #3 ·
I'll snap a few test results when I get back out to the shop tomorrow, what would you be looking for specifically?
 

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Get a good combi relay.
or
Take it apart and clean the contacts. I have not performed this for the double relay, but I have performed this on relays (including Bosch) in the past.

I believe the combi relay powers the ECU. I believe no injector pulse will exist until it is actually running, or if you have a way to spin it...which might be as easy as removing the distributor and spinning it.
 

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Discussion Starter · #7 ·
Get a good combi relay.
or
Take it apart and clean the contacts. I have not performed this for the double relay, but I have performed this on relays (including Bosch) in the past.

I believe the combi relay powers the ECU. I believe no injector pulse will exist until it is actually running, or if you have a way to spin it...which might be as easy as removing the distributor and spinning it.
The combi relay that's in it now is a brand new unit from Bosch, and I've been testing power at the injectors with a noid light and multimeter while cranking the engine. It doesn't seem like the relay is clicking either.
 

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Do you have access to the factory wiring diagrams? This will probably be necessary to go after your issue of no power to the injectors. It could be that the relay is not getting to appropriate input to the relay coil when the ignition is switched on.

The injectors are supposed to to have +12V on both terminals with the key on, engine off, with the constant 12V provided by the combination relay. It is the ECU that switches the second terminal to ground (via pulse-width modulation) to complete the circuit and open the injector solenoid with the engine cranking or running.

As suggested above, it could be that the ECU is not getting a necessary input from the ignition system to provide injector ground pulse.
 

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Discussion Starter · #10 ·
Do you have access to the factory wiring diagrams? This will probably be necessary to go after your issue of no power to the injectors. It could be that the relay is not getting to appropriate input to the relay coil when the ignition is switched on.

The injectors are supposed to to have +12V on both terminals with the key on, engine off, with the constant 12V provided by the combination relay. It is the ECU that switches the second terminal to ground (via pulse-width modulation) to complete the circuit and open the injector solenoid with the engine cranking or running.

As suggested above, it could be that the ECU is not getting a necessary input from the ignition system to provide injector ground pulse.
I do have a copy of the wiring diagrams, I'll take a look at continuity from the coil and distributor. What I'm confused about is why the pump isn't turning on without a jump. Maybe bad AFM switch?
 

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I do have a copy of the wiring diagrams, I'll take a look at continuity from the coil and distributor. What I'm confused about is why the pump isn't turning on without a jump. Maybe bad AFM switch?
Possibly. It is quite easy to check that microswitch---you need to pry the black plastic AFM cover off and then you can inspect the switch contacts.

Here is another good resource for checking the double relay circuit, they are all wired more or less the same:

 

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Discussion Starter · #12 ·
Finally got to the shop and tried tracing a few wires.

I checked continuity of:
Violet starter signal wire (86a of combi relay)
Green/White wire to starter solenoid (86c of combi relay)
Green/Violet wire to pin 4 of DME (86b of combi relay)
Black/Red wire to pin 10 of DME (88a of combi relay)
All three DME connector grounds

Voltage was good at:
Ignition coil
Violet starter signal wire at relay (with key on)
Both main 12v red wires (88y and 88z of combi relay)

Just for fun I used an inline spark tester and all 6 are good. With key on there seems to be no power getting to pin 4 of DME connector (which I understand is meant to turn the unit on) with key in the run position.

Are both combi relay connectors meant to receive 12v power? I feel like I'm missing an input to actually turn the DME on.
 

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This post might help you. Fuel pump needs to run with the afm flap before all else.
 

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Discussion Starter · #14 ·
No power at 88a at relay connector or at AFM. Continuity is good between DME and relay, then relay to AFM on this wire. Scratching my head 🤔
 

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Based on what you have checked and verified so far, I'm suspecting your ignition switch or circuit. Verify that fuses 2, 5 and 8 are actually making good contact with the brass fingers, that is adequate spring pressure.
 

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Discussion Starter · #17 ·
Based on what you have checked and verified so far, I'm suspecting your ignition switch or circuit. Verify that fuses 2, 5 and 8 are actually making good contact with the brass fingers, that is adequate spring pressure.
Just cleaned contacts on all these points, still the same result. Fuses aren't broken but I'll swipe some new ones in the morning just to be sure.
 

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Squeeze the brass fingers together on the fuses as you crank the engine, to ensure good contact. Or just gently bend them inward a bit so you get a good tight fit on the fuse ends.
Jumper the ignition leads, red to brown, to bypass your switch as a test.
 

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Discussion Starter · #19 ·
Squeeze the brass fingers together on the fuses as you crank the engine, to ensure good contact. Or just gently bend them inward a bit so you get a good tight fit on the fuse ends.
Jumper the ignition leads, red to brown, to bypass your switch as a test.
Will do, I'll report back in the AM
 

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I post some Milano specific wiring diagrams here. The OP has colored them in, and that makes it super helpful, even if not for fuel pump.
 
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