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Thread: 280z + battery fusible link no continuty

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    Default 280z + battery fusible link no continuty

    Was having some issues getting the 78 280z to start today, had the roommate squeeze the fusible link connected to the positive battery terminal together and it started, as soon as he removed pressure the car died.

    Had him squeeze real tight and got the plug all wrapped up in electrical tape to hold it. started the car and it died a few moments later, no fuel pressure.

    Checked the fuselink and i have a positive 12v current on the pins from the terminal, but i have no continuity from the other side - from ecu i believe?

    The ECU is new. Tested it on old and new ECU, same result.

    With the fusible link not carrying juice to where it needs to go, the only things working in the car are the dome lights and the radio. No gauges, no fuel pump, nothing important.

    Sorry for bad pic quality. Its late here so not much light. At least I found a use for my google glass finally!

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    Ive confirmed that the ECU harness is getting absolutely no power to any of the pins.

    Any common issues that would prevent the connection from the positive battery terminal to the ecu to complete?

    Im really scratching my head here as this one seems to have totally come out of nowhere.

    Where does the ECU ground come from? If thats broken, I think maybe that could case this?

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    I should also note that none of the other gauges or lights in the car i normally see are working either. The only thing with power is the radio and the dome light.

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    Quote Originally Posted by Ken Kyger View Post
    had the roommate squeeze the fusible link connected to the positive battery terminal together and it started, as soon as he removed pressure the car died.


    Checked the fuselink and i have a positive 12v current on the pins from the terminal, but i have no continuity from the other side - from ecu i believe?
    You have at least one bad fusible link, maybe more. But, the only links I see in your pictures are what might be the EFI harness links (two green ones), which would power the injectors and the ECU. They fail internally, so squeezing and taping them won't work, they have to be replaced.

    I don't even see the other four links. Did someone replace them with fuses? I don't see year of car either so I just copied a picture from 1978.
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    1976 280Z, with some minor modifications

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    Quote Originally Posted by Zed Head View Post
    You have at least one bad fusible link, maybe more. But, the only links I see in your pictures are what might be the EFI harness links (two green ones), which would power the injectors and the ECU. They fail internally, so squeezing and taping them won't work, they have to be replaced.

    I don't even see the other four links. Did someone replace them with fuses? I don't see year of car either so I just copied a picture from 1978.
    "78 280"

    "EFI harness links (two green ones), which would power the injectors and the ECU" thats the one. I have current moving through the wires, so I am 99% sure that the link isnt the issue. If i connect the link to the positive terminal side, i can read the 12v current on the pins on the other side of the link. 12v is making it through the link, but not to the ECU.


    I have seen that diagram a few times, but I actualy dont have #2 at all.

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    I have noticed that I am no longer getting the current from the ECU on the fuel pump relay when the key is turned to on. My fuel pump relay now has one poitive lead - battery - and three negatives.

    There has to be an issue from the EFI harness to the ECU, but that ECU harness is terrifying looking and i have no clue where id even start.

    Again, all ECU tests have been preformed on the OG ECU and a new one.

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    Is my terminology wrong? Is that 2 green wire plug from the positive terminal to the ECU not a fusible link? If so, I may need to update my posts and redo some research using the correct terms

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    Quote Originally Posted by Zed Head View Post
    You have at least one bad fusible link, maybe more. But, the only links I see in your pictures are what might be the EFI harness links (two green ones), which would power the injectors and the ECU. They fail internally, so squeezing and taping them won't work, they have to be replaced.

    I don't even see the other four links. Did someone replace them with fuses? I don't see year of car either so I just copied a picture from 1978.
    Im not seeing any other fuses anywhere other than the fuse box by the passenger footwell, so i have no clue what happened to the #2 in the diagram.

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    As I said, the fusible links can fail with no visible outward damage. They're designed that way to avoid fires and melty stuff. Your two green fusible links are either bad or have bad connections. You need to replace them, they can't be fixed.

    Follow the white wire from the alternator's B terminal. You'll probably find a Maxi-fuse block, or some inline fuses,or the fusible link block. That wire used to go to the fusible link block when it was bolted to the side of the relay cover. The fusible links look a like a short piece of wire with a female connector on each end.
    1976 280Z, with some minor modifications

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    Quote Originally Posted by Zed Head View Post
    As I said, the fusible links can fail with no visible outward damage. They're designed that way to avoid fires and melty stuff. Your two green fusible links are either bad or have bad connections. You need to replace them, they can't be fixed.

    Follow the white wire from the alternator's B terminal. You'll probably find a Maxi-fuse block, or some inline fuses,or the fusible link block. That wire used to go to the fusible link block when it was bolted to the side of the relay cover. The fusible links look a like a short piece of wire with a female connector on each end.
    I can understand that, but if they were bad, would there still be a solid consistent 12v flowing through them?

    It looks like those are inline fuses of some sort?
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    Am calling around now to find a replacement for those links, but to me it doesnt make sense that its the links. If current is flowing through them, id think its a problem further down the line.

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    Not sure what you're saying. You said that the voltage went away. "Checked the fuselink and i have a positive 12v current on the pins from the terminal, but i have no continuity from the other". Plus you're getting continuity (resistance) and voltage measurements mixed up. Good that you're measuring but it's easy to get things confused. You could very well have a light connection inside the fusible link that opens up as soon as current flows. And voltage is not flow, it's just the impetus for flow. What do you see with the key On?

    On the pictures - those are just wires. Google "280z fusible link" and look at some pictures to see what you're looking for. You might also follow the thick white wire back from the start to see where it goes. It also used to be attached to the fusible links block.

    Here's one picture - Post #6. http://www.classiczcars.com/forums/e...-problems.html
    1976 280Z, with some minor modifications

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    Quote Originally Posted by Zed Head View Post
    Not sure what you're saying. You said that the voltage went away. "Checked the fuselink and i have a positive 12v current on the pins from the terminal, but i have no continuity from the other". Plus you're getting continuity (resistance) and voltage measurements mixed up. Good that you're measuring but it's easy to get things confused. You could very well have a light connection inside the fusible link that opens up as soon as current flows. And voltage is not flow, it's just the impetus for flow. What do you see with the key On?

    On the pictures - those are just wires. Google "280z fusible link" and look at some pictures to see what you're looking for. You might also follow the thick white wire back from the start to see where it goes. It also used to be attached to the fusible links block.

    Here's one picture - Post #6. http://www.classiczcars.com/forums/e...-problems.html
    Ya, i absolutely do not have those. In my pic on the right i have a mess of red and white wires - the ones i see going into the fuse link boxes on other peoples car - that lead into a bulged out yellowish connector, then into the blue wires. On first glance i thought they may have had some sort of fuse in there, but no, just connectors.

    Ok, to clarify what i mean with the measurements. Im just testing voltage.

    Ive found some 14g links at advanced auto, but they dont list the amps they are rated for. 14g is whats on there now, I should be good right?

    With the key at on, i see nothing at all. No interior lights, the radio turns off - as expected - no fuel pump
    Last edited by Ken Kyger; 10-24-2014 at 12:54 PM.

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    I can see the white wire that you want to follow, in your first picture. There has to be something at the end of that wire.

    If your main fuse or fusible link is blown, or the Ignition link, then the EFI relay won't work and you won't have power at the ECU. You have to find out what happened to those links, they are the key. Maybe the whole block came unbolted and is hanging down below the oil filter.
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    1976 280Z, with some minor modifications

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    Then they wrap around to meet the blue wires as shown in the pic above.

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    Did PO seriously **** me over or something? I really dont see what i should be seeing here.

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    Omfg. Those blue ones are the links.
    Ok. Were good now. So, you think I need to just replace all the links?

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    Sorry, my mistake, I didn't really look at those blue wires. I thought they were just wires to the pressure sender and other things.


    Disconnect your battery before you start moving things. No need to melt new wires trying to fix problems.


    The PO probably though he was cleaning up the engine bay when he did that. But they're down in the dirty wet area of the engine bay. Plus it looks like he either used plain wire or links of the same gauge.

    You might consider pulling those wires up to a clean safe area, and replacing the blue with the correct links, or wiring in a Maxifuse block. Looks like a pretty good cause for your problem. Check your voltages there.
    Last edited by Zed Head; 10-24-2014 at 01:15 PM.
    1976 280Z, with some minor modifications

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    Just saw the wire nut in #15. The PO has made a mess. You have some work ahead of you.
    1976 280Z, with some minor modifications

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    It actually says fusible link on it after i got a good look, it was just really dirty so i didnt notice the first time. They are 12g, but all i can find around is 14. Would that work still? At least to get the car running again. Im going to go for the maxilink upgrade, but i dont want to have to wait for all the parts to show up to confirm that that was even the problem.

    He used some sort of shrink wrap like connection cover, so thatll be fun to get off.

    If 14g is good there as well as the connection to the ecu, i will go pick up some of that and see if i cant at least get this baby started again.

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    Your dilemma now is to figure out how much downtime you can take with the car, and if you decide on a temporary fix to get by, how to do it. I would disconnect the battery and drag all of those wires up high and dry. Then, for a temporary fix, replace that wire nut with a large crimped connection and some heat shrink or solder and heat shrink. Figure out which circuit is broken among the blue wires and wire in an inline fuse, or a fusible link of the correct gauge. If that blue wire is plain old wire, best to replace them all with fuses or fusible links of the correct capacity.

    Here's a typical fusible link replacement - http://www.atlanticz.ca/zclub/techti...nks/index.html
    1976 280Z, with some minor modifications

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    Quote Originally Posted by Ken Kyger View Post
    If 14g is good there as well as the connection to the ecu, i will go pick up some of that and see if i cant at least get this baby started again.
    You can't damage things by going smaller. Did you find one that was bad? Sometimes you can tell by feel. Or use the meter and measure resistance.
    1976 280Z, with some minor modifications

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    I see some of the shrink wrap on a few of them was melted through a bit. To test them id replace have to cut the wrap open and i figure i may as well replace them at that point anyways.

    i need to pick up 6, replace them all, and start my hunt from the top again.

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    And don't forget the green ones. There's still something weird about the "squeezing and taping" that made things work again, in your first post. The blue ones might be fine. After seeing the wire nut, it could be that there's nothing wrong with those links at all, the problem is somewhere else. Maybe that wire nut just needs another twist.

    You should still make them better, but don't be surprised if they're not the problem.

    At least you know more about your car now.
    1976 280Z, with some minor modifications

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    i hate you PO

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