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Posted on Jun 25, 2009
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Acts like vapor lock

Okay, let's try again. 2.8 MPFI won't start when warm, starts fine when cool. Started a few days ago. Fuel pressure in specs, plugs fire whether engine starts or not, code readings are clear. I know carbed cars have the problem of vapor lock but never heard of FI cars doing it. If not vapor lock whiat could it be?

  • Marvin
    Marvin May 11, 2010

    please post your question once and wait.

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  • Master 3,600 Answers
  • Posted on Jun 25, 2009
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When they went to fuel injection the fuel that was not used returned to the tank thus cooling the fuel and ending vapor lock, my question is did you do a fuel pressure test? and di you do a fuel leak down test? and the first thing I would do is change the fuel filter. with ethanol in the gas it kills the filter. I have to replace mine every three months they just plug up from that junk. Other than that the only other thing would be a coil breaking down when it gets hot the coil shorts out when cool it starts so check those things first. be sure fuel pressure is 50 to 60 PSI and does not drop below 30 PSI for at least a minute, if it does the fuel pump check valve is bad, also the fuel sock could be bad as well.

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2003 Chevrolet Silverado 4.3 V6 with MFI. Engine ran not start.

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Vapor locks

It could be a vapor lock but not likely. Since the introduction of fuel injection vapor lock has been eliminated.
You need to figure out if you are loosing fuel pressure or spark when it will not start back up. Could be a fuel pump relay or ignition module among other things. Even a problem with the vent for the gas tank.
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I have a 1988 Dodge Dynasty that acts like it's vapor locking.

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