electric fuel pump not turning off

[grasshopper]

Hi all. My electrical woe's continue from two previous posts..
When I hook up the battery,my fuel pump starts working even when ignition key is turned off. It only stops working if I take the wires off of my ignition switch. Where do these wires resolve and why is this happening ? I also noticed that even if I have all wires removed from my ignition switch,my clock still works. Is this related ? Between this problem and my previous two posts,im going out of my mind

[zachmac]

https://www.mirafiori.com/faq/content/F ... 1976_8.jpg
First, print out all the wiring diagrams for you car, a 76, correct? A link to the page with the fuel pump is above. Print out all of the others on the Mirafiori site you'll need them.

76 is a unique year, wiring different than any other year as they were still sorting out emissions. In any case the factory wiring powers the fuel pump (#120 on the linked print) via one of two power sources via two relays.

When you first turn on the key the pump should NOT run. Once you go to the cranking position on the ignition switch the pump is powered. Cranking the engine also causes oil pressure to go above a low setpoint and powers the pump to keep the car running when you stop cranking (ignition switch back to run). This was done so that, in theory, if you were in a wreck and the engine stops (oil pressure drops) the fuel pump also cuts off to prevent fule being pimped out of a possible line break vaused by the wreck.

All that said, you'll have to trace all of the wiring and figure out how your pump is actually wired. There is little probability it is still wired the way it came from the factory as many previous owners may not have of understood the factory setup and changed it around. Clearly something is amiss as your pump absolutely shouldn't be running when the key is off.

BTW, the two relays involved are in the cluster of six relays on the drivers side inner fender under the hood. 128/2 and 128/3 on the diagram are the ignition mode relay and the fuel / pump relay, respectively. I'd start there to see if it looks like you have a factory wire setup. You'll need to take continuity reading between the wires coming to the relays there and the fuse box and pump connections. You'll need a multi-meter, long wires lengths to reach the various points and perhaps a friend to help make connections between various remote point.

[zachmac]

BTW, the easy fix to all of this is:

1) run a new wire form a switched fuse (one that has power when the key is in the on position, to a relay in the trunk. Connect that wire to the relay post that turns the relay "on" and "off" (85 or 86 on relay, either).
2) Connect the other relay coil post to ground (85 or 86, either).
3) Wire a wire from the positive battery post to the power input post of the relay (30).
4) Connect the power output post of the relay to one side of a Ford inertia switch (87).
5) Connect the inertia switch output to you fuel pump + post
6) Make sure the other post of the fuel pump has a good ground.

With this setup you eliminate the factory twin relay setup, the pump runs any time the key is on, and the inertia switch shuts the pump off should you be in a collision. Plus you get full voltage from the battery to the pump with no voltage drop.

Here is a link to the inertia switch topic.

http://www.fiatspider.com/f15/viewtopic ... rd#p269638

You actually don't need to run a new wire from the front to the back either. Find the green wire under the dash coming through the fire wall from the fuel pump relay 128/3 and pull it into the compartment through the fire wall. Find a post on the fuse box that is hot when the key is on and connect it there. That then becomes the trigger wire for the relay in the trunk. You can also use the 128/3 relay in the trunk making it the fuel pump relay so you don't need to buy anything other than the inertia switch which you can get on eBay for a few dollars.

[zachmac]

Also, I noticed when you were asking about the distributor wiring in a previous post some folks pointed you to the Artigue 78 wiring diagrams. Use the link I sent you to the 76 diagrams on Mirafiori as there are subtle differences. The wiring for the distributor is on that same page as the fuel pump I linked above. You may simply have a problem with the 128/2 or 128/3 relay but again, you should eliminate both and wire the car in a more simple fashion. The previous posts from others discussed how to wire the distributor and this post tells you how to wire the fuel pump. If you do both you should be able to eliminate the 129/2 and 128/3 relays.

Post your questions as you go and we will try to help. BTW, where are you located? Finding a knowledgeable Fiat owner nearby that can stop by and help will get you there a lot faster than us trying to do this via posts.

[grasshopper]

Thanks for all this info. I will look into all of it and report back. I have one question before I go. I noticed a sound coming from the relay for the fuel pump when I connect the battery. It makes a sound kind of a buzz sound. What does this mean? Is the relay bad or is it a sign of crossed wires or something ?

[zachmac]

Sounds like it is not wired correctly or it is frozen shut which would make the pump run continuously. Check the wire connections versus the prints. The posts are numbered on the relay.

[spider2081]

Sounds like it is not wired correctly or it is frozen shut which would make the pump run continuously.

I think there was a post about changing the original Sipea ignition switch to a Lada ignition switch. This is where a wiring error could have occurred.

[grasshopper]

I have removed the old ignition switch and installed another switch that has more prongs in the back. I have re configured the wiring behind the switch. Now when I turn the key to the off position,the dash lights and the fuel pump turns off. However,as soon as I turn the ignition switch to the on position (turn key 180 degrees),the fuel pump does come on but there is still a hissing sound coming from the fuel pump relay in the engine bay (sounds just like the seatbelt relay that I disconnected) Is this normal? Should the relay be making a sound at all. Should it shut off when the engine is running?..(haven't managed to get her running yet ),,,

[zachmac]

The relay should click when it is first powered and then make no noise.