Hard starting after fuel system cleaner

Discussion in 'Troubleshooting & Diagnosis' started by TheMadDoctor, Sep 2, 2019.

  1. TheMadDoctor

    TheMadDoctor New Member

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    Hey guys, I need your help solving a hard start issue after I used some fuel system cleaner. I regularly use STP fuel system /carb cleaner about every 3 months. About a week ago after adding it, I went to start my daily driver 1979 Camaro, and had to crank for about 20 seconds before she would start. This has become an every day occurrence. If I'm driving around, she starts right up, after 2-3 hours, she starts right up, but 8 hours or more, and I have to crank and crank to get gas to the carb. I'm not smelling gas when I drive, and drivability has not been affected. I tried putting cardboard under the car to see if I could find a leak, but it's the rainy season here in Florida, so I haven't had much luck. Could my fuel pump be going bad? Are there certain spots I should look for on my fuel lines? Any help would be appreciated. Thanks
     
  2. rocket dawg

    rocket dawg Veteran Member

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    Yes a fuel pump can do that. Same problem as you. I had the wrong fuel pump on the car. I thought they were all the same but that isnt the case. For some reason the fuel pump would let the gas siphon back into the tank. A new A/C Delco unit designed for the car( 1979) fixed my problem.
     
  3. TheMadDoctor

    TheMadDoctor New Member

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    Thanks for the advice! I haven't had a chance to get under the car yet, I have been prepping for a hurricane! However, I don't see any fluids leaking near where the fuel lines would be, and only get fuel smell from the engine compartment, but I might just be boiling fuel in the carb on a hot summers day. Additionally, this fuel pump has been in my daily driver for the last 17 years, so it could be worn out. When I look to replace it, should I purchase the 1979 Camaro fuel pump with the larger sump, or should get the correct fuel pump for my 1973 400sbc? One last point of interest, my car has a fuel return line, should I use it, or can I keep using a 2-line fuel pump. I honestly don't know if it's connected to the gas tank or not, my car came without an engine, and the person who I bought the body from said they replaced the gas tank with a larger unit, but I never knew that carbs had return lines.
     
  4. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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    Personally I would use the return line option, it keeps the fuel cooler at the pump but more fittings and possible leak issues but still worth it.
     
  5. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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    AC Delco 40777 Fuel Pump.jpg AC DELCO 40777 standard on a Z28
     
  6. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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    The smaller barbed fitting is the return.
     
  7. TheMadDoctor

    TheMadDoctor New Member

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    Thanks for the information, but it looks like the max psi of 9 might be too much for my Eddy carb. After searching on the forums, I saw recommendations for the Carter M6101, which appears to be mechanically equivalent, but only puts out 6 psi at max. As much as I prefer to use AC Delco parts, do you think the Carter would be an appropriate substitute so I don't have to use a fuel regulator?
     
  8. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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    Not sure but I had to buy a new one, am using a Holley carb, all excess fuel is returned. I did have gauge on the carb and it did read 6 psi without a regulator.
     
  9. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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    Some of the reviews I read were that the orientation of the three fittings on the pump were incorrect, might want to check before ordering.
     
  10. TheMadDoctor

    TheMadDoctor New Member

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    That's what I'm worried about, if your carb fuel gauge reads 6 psi at idle, when you're under the hood looking at it, what happens at 3000 rpm? Is it at 7 psi? Eddy carbs are notorious for hating anything over 6 psi. Since Eddy carbs are based on Carter carbs, I might just go for the Carter pump, but I'm hoping some more voices will chime in first. However, I totally appreciate the input, and thank you for your time. I do love this forum, we have the nicest, most helpful members of any automotive forum I have ever been to.
     

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