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96' hard to start after running A/C

Discussion in '1st Gen. Tacomas (1995-2004)' started by saltbranch, Jul 13, 2009.

  1. Jul 13, 2009 at 5:22 PM
    #1
    saltbranch

    saltbranch [OP] Well-Known Member

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    After driving down the highway w/ a/c on in 95 plus heat today for 50 miles I pull into lumber yard, cut truck off, go get what I need. Get in to go it wont start, it try to fire off but wont(let sit with hood open for 5 min. it fires off). Truck does the same thing when idleing around the ranch with a/c on. Leave the a/c off in both above circumstances, no problem restarting.
    Temp gauge from day 1 has never got over 1/2 way hot on stock guage. Week or so ago I replaced the fan clutch and temp sending unit, thought that had fixed it. I am thinking truck is running hotter than idiot guage is showing, mechanical going tomorrow. Weird thing is after I replaced temp sending unit, dash guage still acts thesame.
     
  2. Jul 13, 2009 at 5:35 PM
    #2
    XBrown

    XBrown Spartacus!

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    Hmm, kind of sounds like vapor lock to me. I believe the ign. coils were right above the exhaust manifold on those. Maybe they're getting too hot?
     
  3. Jul 13, 2009 at 5:48 PM
    #3
    saltbranch

    saltbranch [OP] Well-Known Member

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    I dont know. It only happens when I have the a/c on, then shut down truck. I can literally run the truck for all day in the heat without a/c on, turn off and start at will. Run the a/c and I have a hard time restarting after cutting truck off. After restart with a/c on I catch a smell- like heat if that makes sense. Thing is there is no boiling radiator or anything like that.
     
  4. Jul 13, 2009 at 6:46 PM
    #4
    XBrown

    XBrown Spartacus!

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    Hmmm, barring strange and unusual circumstances, the only other things I can think of are a bypassing fuel pressure regulator, or a leaking check valve in the fuel line. That usually causes fuel pressure to bleed down, but not usually like this. Or also, try and see if the A/C switch has anything to do with it.
     
  5. Jul 13, 2009 at 7:23 PM
    #5
    saltbranch

    saltbranch [OP] Well-Known Member

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    XB can you explain more on the fuel possibility... I dont smell fuel leaks/problems, just a hot motor smell after start up with a/c running. After running a/c and shutting truck off, and trying to restart, the motor turns, trys to fire. I give it gas @ pedal = instant shutdown, no start. I can pop the hood open for 5 min. or so and it will start. Thats why I was leaning more towards heat. I am at a loss on this. I dont get why I can I can run the truck all day with a/c off and have no problems, run the a/c on the hwy or at idle and have problems.Maybe after I hook up a real temp guage will help.... I dunno.
     
  6. Jul 13, 2009 at 8:30 PM
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    XBrown

    XBrown Spartacus!

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    If the pressure regulator sticks open (low fuel pressure position) the pressure in the fuel rail would drop to zero psi, almost immediately after shutting the engine off. If you tried to start it with a stuck open regulator, it would try and run on maybe 10% of the required fuel pressure. You wouldn't smell fuel, because it would all drain back down the return hose and in to the tank.

    One way to check this, is to attach an EFI fuel pressure gauge with the engine hot and running, with the A/C on, and check the pressure. Now shut off the engine, and see what the rest pressure is. If it drops a few psi and holds, that's normal. If it plummets to zero, or sinks slowly to zero, it indicates either a leaking fuel injector, check valve, or pressure regulator.

    What's causing it to only happen when it's hot is hard to say. Maybe the regulator sticks when it's hot, and then closes once it cools off.

    Another worthy mention about fuel injected vehicles. Since they no longer have accelerator pumps, or chokes; hitting the gas while cranking may cause it not to start. On most post-'96, OBD2 vehicles, cranking with the gas pedal past 80% will put the computer in to "Clear Flood" mode, and shut off the fuel injectors.
     
  7. Jul 15, 2009 at 5:24 AM
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    ViperR

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    My 95.5 does the same thing, hard starting after a/c use. My guess is the extra heat as stated above and creating some sort of vapor lock somewhere. Maybe something to do with the location of the fuel filter under the intake manifold? It starts, but takes twice as long. Starts right up after sitting, though. Temp gauge reads the same whether a/c or no a/c use. Not gonna worry, but will look at this post if a solution is found.
     
  8. Jul 15, 2009 at 6:34 PM
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    saltbranch

    saltbranch [OP] Well-Known Member

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    Thanks XB for the breakdown, very helpful info. I learned something new here, thanks.
     
  9. Feb 9, 2010 at 9:28 AM
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    95Tacoma_owner

    95Tacoma_owner New Member

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    I was wondering if you ever found a resolution to this as my 95.5 does the same thing on warm days. Hadn't noticed the A/C vs. not, but what I did figure out is that if I unscrew the gas cap and let the pressure out of the tank, it seems to help it start up a lot faster than just waiting 10-20 minutes more.

    Would love to hear if anyone knows why this might be.
     
  10. Feb 9, 2010 at 9:53 AM
    #10
    YotaDan

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    Sounds to me like it is the alternator. An old alternator my be charging enough under normal circumstances, but with extra draw of the A/C, especially when the A/C has been running for some time, the alternator may not have enough output to overcome the a/c draw.
     
  11. Feb 9, 2010 at 9:48 PM
    #11
    saltbranch

    saltbranch [OP] Well-Known Member

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    In my case its not an alternator problem or charging problem. I have no trouble with turning the motor over with the starter. Its a firing the motor off problem. I am leaning towards XB's explanation. We have had some very chilly weather here in S.Tx this winter.I have had no problem, since the cooler temps have hit us. I think its the fuel regulator to be honest. I'll replace the regulator when the problem comes back as the temps warm up.I keep a can of starting fluid in the truck and use it when it wont fire off. A couple weeks ago we got into the 80's and it would not fire up after I went into a store after pulling in off the hwy.
     
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