I hate electrical work so much

"InfinityAero" (infinityaero) 07/31/2016 at 13:38 • Filed to: None

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Now that I’ve gotten the Fiat back on 4 wheels after 4 months up in the air— of *course* it won’t start now. Ran fine when I put it up on stands...

Car will start with carb cleaner sprayed down the carb barrel, but there’s no juice going to the fuel pump, hence no fuel in the carb, hence no ignition otherwise.

Fuel pump will run with a 2A 12V tender with one lead hooked to the hot wire and one lead hooked to a bolt ground... so I’m really not sure what’s up. I *think* I located the inline fuse, which looked fine.

Looking like I won’t have the car ready for my wedding in 2 weeks, after all :( Can’t afford to drop $400 to have a shop sort it out, at least not until after the honeymoon.... and I’m freakin’ worthless when it comes to electrical work.

EDIT WITH PHOTOS:

From some past research on the Ignition cylinder, it had a blue wire and a blue/red wire spliced together, going into one of the terminals.

From some help on the fiatspider.com forum, they’d identified some things:

Brown wire. “Hot all the time” feeds battery voltage to the ignition switch terminal 30
Blue & blue/red “Hot in start and run” connects to “int” terminal on switch. The “int” terminal is connected to terminal 30 in “start and Run” . position of the ignition switch.

The blue/red wire seems to be the critical one, in this case.

Sorry for the quality, my phone camera sucks— again, another expense I’m saving for a month or so from now

Wires coming out of ignition cylinder, the blue/red one is the one to focus on

Here you can see where the blue/red wires are spliced together with these blue connector things... only the blue/red wire emerges out the other side.

The blue/red wire goes into another blue splice thing, the other input to that splice thing is a brown wire, which goes through this fuse

Meanwhile, the red wire goes directly to the fuel pump. Basically, I think the red wire is directly wired to the blue/red output on the back of the ignition cylinder— it doesn’t seem like that fuse from the brown wire would have any effect. Maybe I can use a scotchlock and run a wire from the blue/red wire to the fuel pump, bypassing the existing red wire, and see if that works...

If only EssExTee could be so grossly incandescent > InfinityAero 07/31/2016 at 13:42

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Does the car use fusible links anywhere?

crowmolly > InfinityAero 07/31/2016 at 13:44

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Get a wiring diagram and get to sleuthing. Yeah, it sucks.

I *think* this may be an issue that we can diagnose and step you through on here, so don’t fret too much.

My bird IS the word > InfinityAero 07/31/2016 at 13:46

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Clean your grounds if you haven't already. They are the source of all evil.

DipodomysDeserti > InfinityAero 07/31/2016 at 13:57

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I second checking your grounds. I had a missing ground wire on a car once and it caused the brake lights to stop working. Weird shit.

XJDano > InfinityAero 07/31/2016 at 13:59

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Two words:

Dollar Dance.

InfinityAero > My bird IS the word 07/31/2016 at 14:08

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Yep, that was the first thing I did after buying a new pump... it was ground to a brake-line support bracket. I switched the ground to the other side of that support bracket and wire brushed it down well. I suppose the next test is to try using one of the mounting bolts of the pump itself as a ground... unless that’s a bad idea for some reason.

InfinityAero > crowmolly 07/31/2016 at 14:09

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The wiring diagrams don’t seem to be of much use— the original pump was a mechanical unit that attached to the crankcase... so it’s not on the wiring diagram.

InfinityAero > InfinityAero 07/31/2016 at 14:10

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It does make note of their being electrical pumps (on later models, or as replacements)... but still doesn’t show it in the diagram, and mentions there’s an inline fuse for it, but doesn’t reference exactly where it is. I believe my unit is a replacement for an original mechanical pump.

InfinityAero > If only EssExTee could be so grossly incandescent 07/31/2016 at 14:12

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Doesn’t appear so...

InfinityAero > DipodomysDeserti 07/31/2016 at 14:14

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Yeah, the grounds run rampant. The issue is bizzare because the pump was running just fine when I put it up on stands.

Tohru > InfinityAero 07/31/2016 at 14:20

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Does it have power after the relay and fuse? If so, just splice in a new jumper wire with a pair of Scotchlocks. I’ve had to do that on a car where a broken wire kept the speedometer from working and fixing that wire meant pulling the dashboard.

Scotchlocks are these:

InfinityAero > Tohru 07/31/2016 at 14:28

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I suppose a Scotchlock would be a good way to determine if it has power after the fuse.... I guess I’d need a multimeter to check whether that’s the case otherwise?

InfinityAero > XJDano 07/31/2016 at 14:29

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Yasssss.... I’m sure we’ll get some cash gifts, and I get paid the weekend we return from the Honeymoon; too bad in her culture I have to pay her younger siblings to get back my shoes (after they steal them)...

Rusty Vandura - www.tinyurl.com/keepoppo > InfinityAero 07/31/2016 at 14:33

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Isn’t Fiat an Italian acronym having to do with electrical?

Rusty Vandura - www.tinyurl.com/keepoppo > InfinityAero 07/31/2016 at 14:35

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Replacing the stock fuel pump is not an option? Sometimes the bits inside the engine can wear down and stop driving the fuel pump.

XJDano > InfinityAero 07/31/2016 at 14:38

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Save that money, wear shoes from goodwill, they can keep them.

Culture shock.

DipodomysDeserti > InfinityAero 07/31/2016 at 14:38

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Weird. Might just be a loose or corroded wire somewhere.

Tohru > InfinityAero 07/31/2016 at 14:41

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Multimeter to determine how much amperage you’re getting.

Test light to determine if there’s power at all and you don’t need specifics.

Test lights are really cheap, and easy. Put the clamp on ground, and stick the “screwdriver” into what you’re testing. If there’s power...

My bird IS the word > InfinityAero 07/31/2016 at 14:46

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I wouldn't know but a bunch of stuff on my car does that.

InfinityAero > Rusty Vandura - www.tinyurl.com/keepoppo 07/31/2016 at 14:50

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Once the mechanical pump gives up the ghost, it gets replaced with an electronic fuel pump. It looks like that was done about 15-20 years ago, I went ahead and replaced the pump with a new one... it’ll run off an external power source but not off the wiring.

crowmolly > InfinityAero 07/31/2016 at 14:50

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Oh, so it’s a retrofit? If so, it’s very likely that something in the wiring is bad.

InfinityAero > Tohru 07/31/2016 at 14:51

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Yeah, I think a test light will definitely be something I pick up in the next couple days.

InfinityAero > crowmolly 07/31/2016 at 14:53

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Pretty much, the wiring was hacked to hell by POs so the stock wiring diagrams are only half relevant. Ignition cylinder was rewired (wrong), so I have to leave the key in, in the ACC position, to avoid running some of the accessories. It’s about like trying to follow a map of London designed in the 1850s, sure, some of the streets are the same... but otherwise it’s a bit of a clusterfuck... I was planning on having a shop rewire the ignition cylinder correctly for me; I tried a couple times and only made it worse— just reverted my changes.

crowmolly > InfinityAero 07/31/2016 at 14:57

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OK, got ya.

Step 1: Check all of the crimped-on connections in the fuel pump wiring if there are any.

Anything like this:

Tohru > InfinityAero 07/31/2016 at 15:08

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What I would do in your situation:

1. Check to see if fuel pump relay works. It will click when the key is turned on.

If no, replace relay.

2. Check before and after fuse with test light.

If no light before fuse, wire between relay and fuse is bad. Jumper a new wire in with Scotchlocks. If no light after fuse, replace fuse.

3. If test light shows power after the fuse but not at the tank, the wire between the fuse and the tank is bad. Jumper a new wire in with Scotchlocks.

4. Tell yourself that the jumpered wire is a temporary fix and that you’ll do it right at a later date.

5. Drive it for several years with the jumpered wire.

InfinityAero > Tohru 07/31/2016 at 15:16

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Added photos of what’s going on...

InfinityAero > Tohru 07/31/2016 at 15:19

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1) No click— I used to hear a clicking noise with the old pump before it stopped working, a slow rhythmic click when it was in the “on” position. So... I guess I have a bad fuel pump relay.

I added photos of the line going to the fuel pump; seems like it’s basically directly wired to the ignition cylinder— I don’t see how a fuel pump relay would even effect it, but I’m unsure how all this works tbh.

InfinityAero > crowmolly 07/31/2016 at 15:35

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From what I can tell the PO had wired it to run directly from one of the pegs on the ignition cylinder. I think my solution may be to re-splice to that wire or splice in a new one; maybe the splice he used has failed.

crowmolly > InfinityAero 07/31/2016 at 15:36

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Bingo. Start there, and add a fusible link if there isn’t one already.

InfinityAero > crowmolly 07/31/2016 at 15:39

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Cool, a fusible link is basically an type of inline fuse, right? Would they have those at auto parts stores?

InfinityAero > crowmolly 07/31/2016 at 15:47

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Looks like I need to use a 5A fuse in the wiring per the instructions that came with the new pump, and that the PO hadn’t used an in-line fuse at all. That should help with longterm longevity.... :-p

crowmolly > InfinityAero 07/31/2016 at 15:56

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I apologize, I mean an inline fuse holder. Very common at auto stores.

crowmolly > InfinityAero 07/31/2016 at 15:57

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Which pump? Would it be a Holley by chance?

InfinityAero > crowmolly 07/31/2016 at 16:03

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Alas, no, it’s a “Mr. Gasket” brand. It’s what they had at autozone— the requirements are pretty lax for a small carb’d motor’s fuel pump... it operates at like 4-7 PSI and draws only 2A.

Rusty Vandura - www.tinyurl.com/keepoppo > InfinityAero 07/31/2016 at 16:58

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Give it a hot wire of its own, on an appropriately rated inline fuse, and install a relay that’s connected to an ignition-on power source. That’s what I would do on my own auto.

InfinityAero > Rusty Vandura - www.tinyurl.com/keepoppo 07/31/2016 at 17:22

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Thanks, yah, now that I have the carpeting pulled back I may as well run a whole new wire, just to make sure. I’ll try splicing it to the R/B wire, which is supposedly INT, or on during run/start.

Tohru > InfinityAero 07/31/2016 at 18:35

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When fuel pumps shit the bed they usually take other components along with them. Project $300 (2000 Grand Am) cooked both the fuse and the fuel pump relay when the pump died.

On some old vehicles it would’ve ran just from the ignition to the fuel pump, but that’s a lot of current through that switch and it started fires. So they started using relays. (Headlights used to run all the power through the switch too, and had the same issue, so those use relays too.) The wire from the ignition system is just a sense wire that triggers the fuel pump relay (“red fuel pump power wire” in the below picture).

Here’s a simple fuel pump circuit breakdown:

If you want, you can make something like this from scratch very easily.

You’d need some 12 gauge and 16 gauge wire, a fuse holder (to match your car you probably need a glass fuse-type, 30amp, 12 gauge wire), 4 spade terminals (female), 1 ring connector, 2 Scotchlocks, 2 crimp-type butt connector, and a 5-pin relay (like Dorman # 88069). Most universal 5-pin relays follow the wiring pattern in the picture above.

From your battery or a 12V+ distribution point, attach the fuse holder, then run the wire to where you’re mounting the relay. Most universal relays are designed to be mounted to an inner fender or firewall.

The 12V+ source goes to pin 30. Scotchlock off the switched 12V from the ignition and run it to pin 86. Extend the positive wire from the fuel pump (either cut the wire and butt connector it, or use a Scotchlock) and connect it to pin 87. Ground the relay to the chassis at pin 85. Don’t use pin 87a.