Fuel pump wiring into Marelli switch... - Alfa Romeo Bulletin Board & Forums
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post #1 of 19 (permalink) Old 03-10-2011, 07:48 PM Thread Starter
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Fuel pump wiring into Marelli switch...

Ciao Alfisti!!
I recently replaced the rubber fuel lines in the car and decided to also add a proper fuel pump. The one that I ordered is the Facet that IAP has. I removed the 2 wire pump and the brace that is bolted to the car. I cleaned, replaced and mounted the brace and new fuel pump. In all the excitement, I forgot to note how the pump was wired. There is a Magneti MArelli "relay?" that is mounted next to the pump, there is a pink wire running into one side of it(which is power from the fuse box). The old pump had 2 wires, while the new one has just the one. I realize that the new pump grounds to the car-but where does the power wire go? Does it plug next to the pink wire? The marelli relay has 2 screws, as I said the pink wire goes into 1 screw. I hope this makes sense. As always I await your responses.
Thanks yet again...

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post #2 of 19 (permalink) Old 03-10-2011, 11:09 PM
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I don't recall any of the early (pre-Bosch) Spider's having a fuel pump relay, whether they had carbs or were Spica injected. Papajam has all the wiring diagrams and knows for sure. Maybe a previous owner added the relay to increase voltage to the pump, as old semi-corroded wires and ignition switch contacts can cause a low-voltage condition, which in turn causes low fuel pressure.

Also, is your car Spica injected? I thought Facet only made a low-pressure, low-volume pump only suitable for carbs.

Do you have a picture of the relay?
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post #3 of 19 (permalink) Old 03-11-2011, 04:39 AM
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If your car is a 1970 1750 camtail then it is presumably a European spec car with carbs - Solex? If so, it originally had a mechanical fuel pump and the wiring for your electric pump has been installed by a PO. You may have to trace it out. If I were doing it, I would start with a circuit that is turned on by the ignition switch - the wire to the coil for instance, and use it to pull in a relay which would then turn on the fuel pump. Maybe that is what you have.

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post #4 of 19 (permalink) Old 03-11-2011, 02:30 PM Thread Starter
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I am not sure if it is a relay or something else. It is a brown square shaped piece with 2 brass terminals.It is mounted next to the pump. The car had a Spica and was converted to carbs-it isn't european(i know 1970 no import but the car is tilted as a 1970, and was built in early 1970).BTW the piece in question is Magnetti Marelli. I'll try to post a pic later
Does any one have a single wire electric pump and how is it wired?

Thanks for the responses..

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post #5 of 19 (permalink) Old 03-18-2011, 05:49 PM Thread Starter
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Finally got around to taking the pics and running a test. The wire running to the unit is power, and when I touch the test light on the other terminal, it lights as well. Seems to me that the power from the fuse box runs to it and the other terminal connects to the power wire from the pump? Am I correct? Also the pump should "self ground"? I included a picture of the filter that I got from IAP- there is no indication as to which side is which-although 1 side says flow(no arrow). I believe that the "flow" side runs to the tank? Does anyone have this filter that can comment as the filter is slightly different shaped on both sides..thanks
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post #6 of 19 (permalink) Old 03-18-2011, 06:06 PM
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That "switch" is a ballast resistor from an ignition coil. What it's doing there, I have no clue.
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post #7 of 19 (permalink) Old 03-18-2011, 06:20 PM
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Sorry, forgot to answer you other questions, but first you need to remove the existing wiring (is that duct tape I'm seeing in the 2nd pic?).

You want a 14ga. power wire, switched on/off by the ignition, running the length of the chassis, and I'd put a fuse close to the end of the wire coming from under the dash. I'm sure the pump is "self-grounding" by its mounting bolts, but make sure the place it's mounted to has a clean shiny surface, or you'll have a poor ground and low voltage. If there is a ground wire on the pump, put a ring terminal on it, a install it under one of the mounting screws. Throw away that resistor - maybe one terminal on it was just being used to fasten two wires together, because the power wire from the front was too short? Don't know what to tell you about the fuel filter.

Last edited by Kilgore Trout; 03-18-2011 at 06:24 PM.
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post #8 of 19 (permalink) Old 03-18-2011, 06:35 PM Thread Starter
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Thanks kilgore. Thats not duct tape-its black tape. The original pink wire is there-I think its 14g. A fuse should be mounted close to the pump you say? What voltage would you say?
BTW where if anywhere, would that ballast resistor be from? I don't believe that I have one under the hood. Does it have any protection value?

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post #9 of 19 (permalink) Old 03-18-2011, 06:41 PM
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The ballast resistor may be of value to you if you are using an old points distributor. Throw it if you have an electronic ignition.

Ed Prytherch
79 Spider
85 GTV6 3L

A government big enough to give you everything you want is a government strong enough to take everything you have.
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post #10 of 19 (permalink) Old 03-18-2011, 06:44 PM
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No taped connections - there will be voltage drops, corrosion, the potential for a short circuit to ground. The fuse should be under the dash, close to your power source, so if the wire accidentally becomes grounded anywhere along its length, the fuse will blow and protect the car. Really, run a new wire, and don't repeat the bad habits of the previous owner. Use an inline fuse holder, and a 5-amp fuse will be fine.

The ballast resistor should be mounted on the coil bracket, to protect the points. but not all coils or systems need one. What do you have for a coil and distributor? I don't have a wiring diagram for the resistor, but again, Papajam is the keeper of all schematics.

Last edited by Kilgore Trout; 03-18-2011 at 06:48 PM.
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post #11 of 19 (permalink) Old 03-18-2011, 06:52 PM
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Just thought of this. Since your car was a Spica car, there is already a handy power source and fuse under the dash. To the left of your main fuse box, there is a little fuse box (2 fuses) you can use.

The original Spica rear fuel pump wire might still be there, and it might even be that pink wire. If so, and it's too short, extend it with a butt connector, but do it inside the trunk rather than under the car.
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post #12 of 19 (permalink) Old 03-18-2011, 06:56 PM
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Trout is right. Just use the wiring for the original pump.

Ed Prytherch
79 Spider
85 GTV6 3L

A government big enough to give you everything you want is a government strong enough to take everything you have.
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post #13 of 19 (permalink) Old 03-18-2011, 07:11 PM Thread Starter
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Ya the pump fuse is under the dash and the wire is sourced from there.
The ignition is a marelli points with a bosch blue coil

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post #14 of 19 (permalink) Old 03-18-2011, 07:14 PM
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You don't need the ballast resistor with a blue coil - it has a built in resistor.

Ed Prytherch
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85 GTV6 3L

A government big enough to give you everything you want is a government strong enough to take everything you have.
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post #15 of 19 (permalink) Old 03-18-2011, 07:21 PM Thread Starter
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thanks alfa p and kilgore
This forum never disappoints!

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