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Thread: Fuel Delivery Issue Solved (?)

  1. #1
    Registered User HermanM's Avatar
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    Thumbs up Fuel Delivery Issue Solved (?)

    It's been a little while since I have posted on here. Last time I had was right around ZCON right when I started having issues with my car having issue which appeared to be percolation or even vapor lock, which I assumed could be within the engine bay itself.

    After switching out the NEW mechanical pump for another new one and wrapping up the fuel lines with header tape to prevent percolation, I headed to ZCON where I didn't make it to Bakersfield (from Sacramento) without having the issue again. So I towed it over the grapevine to a true auto part shop that had the parts that I would need in order to get her up and running again.

    Getting under the car, I found that the PO dropped the tank before at some point and swapped the return and feed lines at the tank, bypassed the electric pump from the tank (bc 260's had them). So that got fixed and I swapped the old, working, electric pump for a new one and got her back on the road.

    Made it all the way around San Diego without having any issues.... Until we left. This time, I didn't make it to the grapevine and I had to catch a ride with others from the caravan home and get my Z towed home (god bless uship.com for that one).

    Since she has been home I tried getting her around from time to time and I couldn't kick the issue. So I started to drop the tank bc that would be the last issue within the fuel system that I hadn't touched or even looked at yet. I got the sending unit out, sending and return lines out, fill neck off and the vent line from the drivers side off. I dropped the tank a little bit lower to try and remove the top two lines from the tank, just to see it slip onto my lap bc the PO cut the line near the spare tire, left it hanging, and pulled the line from the front of the tank at the top vent area and proceeded to then wrap the two vent lines with electric tape causing my tank to create a vacuum and wouldn't allow my tank to feed fuel to the lines and into the engine.

    I will now drop of my tank to the shop on Monday to get it dipped and cleaned out OFFICIALLY and then run new lines from the tank to all the vent areas and hope that THIS SHOULD cure all my fuel delivery issues.
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  2. #2
    Registered User rossiz's Avatar
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    wow... what a mess! at least when you've gone through it all yourself and made things right you'll have the peace of mind knowing what ISN'T the problem going forward...
    '78 280z - Daily driver/work in progress...

  3. #3
    Registered User HermanM's Avatar
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    Quote Originally Posted by rossiz View Post
    wow... what a mess! at least when you've gone through it all yourself and made things right you'll have the peace of mind knowing what ISN'T the problem going forward...
    Well this is the hope, yes. I will find out for sure next week when I get it cleaned out then run all new lines

  4. #4
    Boat Anchor Repairman Captain Obvious's Avatar
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    Well I sure hope that's truly the issue and don't want to rain on any pre-parade celebration,

    But...

    Your fuel filler cap is supposed to prevent vaccum buildup in the fuel tank. Shouldn't really matter if those lines were blocked off or not (unless you've got a non-venting fuel cap).

    I mean, I wish you the best here, but don't want you thinking you've found the smoking gun. Yet.

    Don't shoot the messenger?

  5. #5
    Registered User HermanM's Avatar
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    L
    Quote Originally Posted by Captain Obvious View Post
    Well I sure hope that's truly the issue and don't want to rain on any pre-parade celebration,

    But...

    Your fuel filler cap is supposed to prevent vaccum buildup in the fuel tank. Shouldn't really matter if those lines were blocked off or not (unless you've got a non-venting fuel cap).

    I mean, I wish you the best here, but don't want you thinking you've found the smoking gun. Yet.

    Don't shoot the messenger?
    Yeah, I understand that but the filler cap was awesome before hand and I was able to drive until the vacuum build up within the tank. Once the cap was loosened the vacuum was released and the lines worked good.

    So now I'm looking for affordable lines to put into the vent ports

  6. #6
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    Did you inhale some air through it?
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    1976 280Z, with some minor modifications

  7. #7
    Registered User Stanley's Avatar
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    Using the little fuel return line as the main fuel line sounds totally whack. Seems like it couldn't supply enough gas, on a grade at freeway speed for example. And it's so easy to bypass the electric fuel pump with just a piece of rubber fuel hose and a hose splicer. Besides, the car should run fine with the electric pump in line, even if it's not powered. In that case it acts as a fuel filter.

    Sometimes I wonder about all those vents. Why two vents on top of the tank, besides the vented cap, and one from the filler hose. One wasn't enough? And that expansion tank - wasn't it used as a fuel reservoir for the Z432's? AUS Z's never had them if I remember correctly. Some have removed the tank and report no problems. And there's the whole enigmatic flow guide system that vents the expansion tank (need to test that by blowing into it too).

    There's a nice tech article on this site about replacing the vent hoses. But as I said, I wonder about the necessity of all that stuff.

  8. #8
    Registered User HermanM's Avatar
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    They were necessary, assuming here, bc the 260 have issues with vapor lock as percolation. Most tanks have the vent at the full neck, my tank does not. It just has them at the high point of the tank to allow the air to push it down into the lines. This is the same reason for the eletric pump, which with my mods, should be unnecessary

  9. #9
    Registered User beermanpete's Avatar
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    I think the evap sytem uses a fuel tank vent at each corner of the fuel tank so no matter what there is always a vent open above the fuel level, even if the tank is full and the car is parked on a slope. When the evap system is working as designed, air is adimitted in through the cap but vapors are only allowed to exit through the guide valve and into the charcoal canister for storage, to be burned off in the engine when started later.

    If you are actually having vapor lock problems, adding an electric fuel pump at the rear of the car will help.

  10. #10
    Z geek at large FastWoman's Avatar
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    I still think it's turbulence from that enormous hood ornament.

    The PO cut the return line for some reason, as misguided as that might have been. It might be that the return line is blocked with rust. You might even have a bit of that issue with the supply line. You should investigate those possibilities. Also, is that some sort of red goo in the bottom of your tank? I'm not quite sure what I'm seeing in that photo. Red goo could be betty betty bad. Or maybe that's some sort of gas tank sealer? Is it gooey or hard? Is there rust and dirt in whatever you drained from the tank? Is there red goo?
    My last three sports cars while I still owned all three:

    2001 BMW Z3 Roadster 3.0i soft/hard top (sold)
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  11. #11
    Registered User siteunseen's Avatar
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    That red goo looks like a half done Red Kote tank lining. Reads like the PO dropped the tank to seal it and saw what a PITA it is and slapped it all back on too quick. That stuff takes at least a week to cure. I don't think he waited and got in a hurry with the hoses too, maybe his daily driver?

    I would check the fuel hardlines from the tank to the engine bay with an air gun to see if you have blockage there from the uncured Red Kote.

    Here's a picture of mine after lining it, looks very similar in color.
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    1972 240Z #918 New Sight Orange
    1977 280Z #305 Light Blue Metallic
    1972 240Z #110 Persimmons Red

  12. #12
    Registered User conedodger's Avatar
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    I doubt that's your problem Herman. This sounds like a job for Gary Cook. Sorry I didn't get back to you on Facebook. Working 60-70 hours a week lately.
    Rob
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  13. #13
    Registered User HermanM's Avatar
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    Quote Originally Posted by conedodger View Post
    I doubt that's your problem Herman. This sounds like a job for Gary Cook. Sorry I didn't get back to you on Facebook. Working 60-70 hours a week lately.
    No worries Rob. I talked to Gary on the phone and he told me to just take it to the shop he takes all of his tanks to for the boil out. I was going to swing by before I take it to the shop and probably after it too

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