Fuel pump wiring for 1980 carbureted X

[Regan Burba]

Hi everyone, the 1980 X I have came with the FI removed and duel Weber carbs installed. I do not believe the wiring for the fuel pump is correct or safe. From what I have read here it can be wired to the oil pressure sender. The info I have seen here seems to be geared towards wiring a fuel pump for a older carbureted X. Can anyone provide info on how to do this? Keeping in mind that I am just so so with electrical. Any help is appreciated.

 

[carl]

What I do is get a volt meter and first check any disconnected wires in the engine bay I can use for a power supply for the pump. I'm not up on FI so I can't tell you which wires may work. My current X has a home built wiring harness so again I can't help pick a particular wire. On many spiders and Xs I had to just find some unused wire with 12v when the ignition is turned on. Some folks use the 12v wire going to the coil but I don't like to do that.
Both my current Fiats have no safety device in the wiring, just a simple on/off switch on the dash. If I was to use a safety cutoff I'd use an inertia switch. I had a 128 with the Fiat wiring to cut off the fuel pump if oil pressure was lost and got stranded on the side of the road when the oil light switch broke and gave a false, "no oil pressure" signal.

 

[Dr.Jeff]

How did it go with the front struts / camber plate removal?

The info I have seen here seems to be geared towards wiring a fuel pump for a older carbureted X.

The general principle of wiring an electric fuel pump will be basically the same for older carb models, so that shouldn't matter with regard to how you design the circuit. Whether it was FI or carb would only make a difference in the original wiring harness arrangement. Also some '80 models were not fuel injected, is it possible your's already had a carb then converted to dual carbs? But again, it really doesn't matter that much because you are using an aftermarket electric fuel pump that can be wired to any vehicle regardless of how if came from the factory.

I do not believe the wiring for the fuel pump is correct or safe.

What is not correct about the current arrangement? How is it currently wired?

From what I have read here it can be wired to the oil pressure sender.

Using the low oil pressure circuit as a safety cut-off does not make a lot of sense to me. First, that circuit only activates after the oil pressure has become almost non-existent. At which point there is still enough fuel in the carb bowls to keep the engine running for several minutes...so it really won't save the engine. Second, the point of cutting-off the fuel pump would be more in the case of an accident or roll-over to help prevent fires. So the oil pressure circuit won't help there. Like Carl said, use of an inertia switch would make more sense. But frankly if the X were involved in a crash severe enough to warrant fire danger...well your already dead.

Joking aside, give a little more info on what you currently have so we can offer more feedback.

 

[Regan Burba]

Hi, the struts and camber plates are for the 87 X, waiting for the end of the driving season to work on it (which will be soon in CT). In process of gathering parts for project, decided to weld in stock strut mounts.
The 80 was FI, The car came with the old FI in a box. The fuel pump was wired to a switch, it seems to have been an unprotected circuit. I would rather it be turned on and off with the ignition, I know either my son or I would forget to turn it off with a switch. The wires in the relay and fuel pump appear to be stock at this point, minus the switch that was wired into relay. I would likely add an inertia switch later on but for now I just want to get car running so I can move it in and out of garage. Since We purchased the cars we have been working on the 87. The 80 has a new motor and transmission but body needs a lot of work. Thought about it being a parts car but son does not like that idea. Let me know if you need more info.

 

[Dr.Jeff]

Thanks, I have a better idea of what you're dealing with. For the sake of building a safe, reliable circuit to power the pump, and not spend a ton of time doing it (so you can at least move it around for now), I'd make a new dedicated circuit for it.

Locate a "switched" source on the fuse box (use a volt meter / test-light to verify it is a switched source; i.e. ignition key switches it hot/cold). Piggy-back a new wire from that source to an inline fuse, and a relay. This is the low current side.

Wire the pump to the relay (also fused on this high-current side). Use heavy enough wire gauge on this side to support the pump's electrical load.

Here is a generic wire diagram of a relay circuit (found online) to help get a visual:

When the key is "on", the relay is energized (low side), which connects the high side (12V) to the pump. Key "off" = no juice to pump. You can go back later on and make it a bit more clean.

Note there are a couple types of relays with slightly different connections. A simple 4-pole relay is all you need (this illustration shows a 5-pole but the 5th terminal is not used). If you have more questions about types of relays: http://www.12voltplanet.co.uk/relay-guide.html

For more info on adding fuses: http://www.12voltplanet.co.uk/fuses-guide-uses.html

For general 12V info (wire gauge selection, etc) take a look at this site (very easy to follow): http://www.bcae1.com/

 

[Regan Burba]

Thanks for the replies and all of the info, I'll give it a go and see if I can get thing started.

 

[LarryC]

I used a relay and installed it in the side bezel next to the electronic ignition box. With voltage to the pump sourced directly from the battery via the relay quirky things like the electric pump changing speed with the turn signal blinking was eliminated. Instead of the oil pressure kill switch, which everybody always recommends, I use an inertia switch as used on modern FI cars. I mean, seriously, the only reason to use an electric pump is the absolutely wonderful fact that it runs when you turn the ignition on, especially so after a month or even a week of sitting. FIres right up with a full float chamber on a carbed X every time.

 

[Rod Midkiff]

another quick easy temp fix. use the power for the rear window defrost circuit. Already has a nice switch and an indicator on the dashboard. (I have a problem somewhere with my wife's car and we have a jumper powering the fuel pump currently from this.)

 

[Regan Burba]

Hi, thought I would give updates on a few questions I previously posted about. For the strut towers on the 87X
I was able to obtain the tops of the strut tower from a donor car and a pair of original front struts ( from meeting great people through the Fiat club in my area). I decided to cut the top plate of the donor piece off around the perimeter and weld to the top of the old (cut back) tower piece. Came out rather well, I think. One exception is some parts of the hood are hitting the new piece, should be able to fix with a little grinding, lol.
I was very surprised that the tolerances were so close. Hindsight, yeah I should have checked. Got one side done before I had to store the car at a friends so my wife can have that side of the garage for the winter.
As far as the wiring on the 80, my son and I got it running. Wired the fuel pump as recommended by you folks. Had some trouble at first but determined the issue was in the ignition switch. Took the switch out and cleaned it with electrical cleaner, but did not take it apart (thought about it, glad I didn’t). I later found out from Dan from Fun Imports And Toys in Vernon CT that he repairs them
(I live nearby). I will take it to him later on. Anyways X started right up and runs great. The engine and tranny are both newly rebuilt by PO, unfortunately the car sat for sometime outside before we bought it, so the body has some issues. Should be able to address them but is going to take a considerable amount of work, but we’ll get there. Wish we could find a nicer body in our area without the drive train, but I don’t anticipate finding one, can’t really spend much on one anyways. If anybody knows of one I may be interested though, we are in New England. It really needs a passenger door. Other than the body the cars pretty awesome though, duel webers, performance springs and Konis. Drove it around the block a few times, it is a much different ride than the 87. Will probably try to get some welding done to it this winter, can do that when it’s cold anyways.