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Thread: 1980 280z mixture issue?

  1. #1
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    Default 1980 280z mixture issue?

    hello im new on this site and have just brought a very tidy 1980 280z (looks like the zx) (car had only done 6500km in 11 years) i drove it 700km home with no issues but the next day it just wouldnt run right.
    was running on 3 or cylinders. after finding crap in the tank had gone thru the pump and filter, the injectors we blocked.
    they were serviced and new pump and fuel reg replaced but now when you give it a bit of a squirt it gets to about 3500 rpm the car dies and makes a pre ignition bang in the engine bay.
    plugs are black. i have also changed plugs,leads,coil,rotor and cap. still runs rich.
    im just about to give up but thought i would ask around to see if anyone has any ideas.
    timing has been checked also.

    any help would be greatly appreciated

    Cheers

  2. #2
    Registered User EuroDat's Avatar
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    Hi 6pak,
    Welcome to the club. I have the 280Z (S30) which uses almost the same FI system for the engine. There is not much you can adjust on these systems and the ECU tend to lean out over time. Rich is mostly because a component is failing or wrongly adjusted/installed.

    Was it running rich when you drove it the 700km? Could be several things causing rich conditions, but if it started after changing the injectors, it could be as simple as wrong capacity injectors or the FPR (fuel pressure regulator) is set too high.

    If it just started then I would check the fuel pressure and also the fuel injectors. They should be the 188cc units, but you might have the turbo model injectors. You could flow test them against one or two "good" functioning old injectors.

    Fit a guage in the fuel line between the filter and the FPR to check the presuure. If you check the forum section in the 280Z fuel injection system, you will find threads on this. The FPR should be somewhere around 25-28psi at idle and max at 36psi when you remove the vacuum line from the FPR. Its important that its not always sending 36psi pressure, that will make it run rich.

    Here is a site for manuals and reference material: XenonS130 - S130 Reference

    Good luck solving your problem.
    Chas
    Chas
    5/77 280Z HLS30 403100 with some modifications
    Original colour: 305 Light Blue. The PO changed it to Red

  3. #3
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    After you check the things above, if you don't find anything wrong, open up the 1980 Engine Fuel chapter here - Index of /FSM/280z

    And use the 1980 280Z/280ZX Electronic Fuel Injection Guide (aka Bible) here - XenonS130 - S130 Reference

    The cylinder head temperature sensor (CHTS), or coolant temperature sensor, is one important circuit to check for rich running. The Guide has good diagrams of the pins to check at the ECU connector. The two books together are great for really understanding the system. You'll need an ohm-meter.
    1976 280Z, with some minor modifications

  4. #4
    Registered User siteunseen's Avatar
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    Make sure the "Bullet Connectors" are clean and plugged together firmly, http://atlanticz.ca/zclub/techtips/e...ons/index.html.

    More on EFI, Z Tech Tips EFI & Fuel (AtlanticZ.ca) || | | | | | | |
    1972 240Z #918 New Sight Orange
    1977 280Z #305 Light Blue Metallic
    1972 240Z #110 Persimmons Red

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    Thanks! I know the pressure is set at 36psi at idle so I will change it, and yes it seemed to drive home ok.

  6. #6
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    Thanks for that also! I'll go check connectors, it has been sitting for years so something has to give, cheers for your help

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