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Thread: Running out of gas symptoms

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  1. #1
    Darth Vader Rut's Avatar
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    Running out of gas symptoms

    Good morning all. I have a somewhat minor problem that Iíve been unable to solve on the MGB. When running along at 65+, in 4th or 4th OD for 10 minutes or so, the engine sounds like itís being starved for fuel. Itís a performance build using a later block after I blew up my original 1970 engine...9.5:1, VP12 cam, Abarth exhaust system, big valves, etc. Iíve removed the vented gas cap, checked the fuel filters and verified that the fuel pump is working well. I have a new gas tank and rubber lines, but the original hard fuel lines. The carbs have been rebuilt and adjusted and it runs just a touch rich, but not bad and drivability is excellent. If I let off the gas for about 5-10 seconds it cures itself until I run another 10 minutes at speed. This has been going on for a couple of years, but hasn't bothered me enough to seek help...I thought I could figure it out. Now I need your expert trouble shooting to guide me!
    Thanks, Rut
    Rut, '60 Bugeye, '70 MGB, '62 TR4, '66 TR4a IRS, '67 TR4a IRS, '68 TR4a IRS, '72 TR6

    When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon


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    Great Pumpkin NutmegCT's Avatar
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    Re: Running out of gas symptoms

    Just a thought, but you say the fuel pump is working well. Is it the right fuel pump (providing sufficient pressure) for the engine/carb setup you have?
    Tom M.
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

  3. #3
    Luke Skywalker
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    Re: Running out of gas symptoms

    Had this symptom with a car years ago....turned out to be a small rub on the hard line. It wouldn’t leak petrol when stopped, so was a joy to find.
    Cheers,
    D.
    "If it's got t*ts or tyres, you've got problems"
    www.englishmotorsatfairbrook.org
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  4. #4
    Darth Vader Rut's Avatar
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    Re: Running out of gas symptoms

    I’ll check both the hard line and fuel pump for leaks, pressure and flow. Iirc, the fuel pump is a generic 2-4# variety that replaced the pump that was on the car when I bought it. Thanks for the thoughts and it could be either one of those issues, but never any smell of gas.
    Rut
    Rut, '60 Bugeye, '70 MGB, '62 TR4, '66 TR4a IRS, '67 TR4a IRS, '68 TR4a IRS, '72 TR6

    When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon


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    Obi Wan Stewart's Avatar
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    Re: Running out of gas symptoms

    If you're still using the metal braided lines to the fuel pump inspect them for cracks and if they are hard. I kept loosing power randomly as they had cracked and would randomly suck air starving the engine of fuel. I cut the banjo fittings off and replaced the hoses with the gates barricade hose. Also it could be electrical. I had something similar in my gt and in the end it was a bit of corrosion at the big wire junction on the right side of the engine bay. Look for the white wires and give them a good cleaning.
    1975 Titanium Grey Metallic Supercharged MGB.
    Restoration of the 75MGB

    You Can't Prove It Won't Happen

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    Obi Wan
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    Re: Running out of gas symptoms

    Water in the gas?

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    Great Pumpkin DrEntropy's Avatar
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    Re: Running out of gas symptoms

    Insufficient volume from the pump? Pump gets too warm after running at higher speeds and starts to fail intermittently? Full tank vs. less than half full?

    My WAG would be to replace the pump with a Jag/Rolls "double-side" S.U. Not cheap but correct pressure and good volume through the whole range. That pump supplies V-12 Jag (four Zed-S carbs) and V-8 Rolls (two HUGE SU's) engines. It would keep up with what you describe as the engine build.
    '64 MGB, '67 Lotus Elan S-3 DHC,'69 Lotus Elan +2
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    Darth Vader Rut's Avatar
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    Re: Running out of gas symptoms

    Thanks again and once I get my back up and running I’ll check all this out. I’ve got a few other things I need to check out that I’ve neglected over the last year, so I’ll add these to the growing list.
    Thanks, Rut
    Rut, '60 Bugeye, '70 MGB, '62 TR4, '66 TR4a IRS, '67 TR4a IRS, '68 TR4a IRS, '72 TR6

    When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon


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