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  1. #1

    Default Misfire and hard starting when hot

    I am at a loss. I have a 99 3/4 ton burban with the vortec 454. My issues began with a starting problem. When the engine is cold, it starts normally. After driving the vehicle and warming it up, letting it sit for 30 minutes or more, the thing won't start easily. It cranks.......cranks some more.... and finally fires up. When it finally does fire, there is a strong fuel smell. I have read that the fuel pressure regulator can cause this problem, so I changed it. I also had the injectors rebuilt. The guy at the fuel injection shop told me that four of them were leaking past the seat, but after rebuilding them, they worked as they should. After reassembling everything, I still have the same problem. I checked my fuel pressure, and it is between 55 and 60 pounds, as it should be. The only odd thing about the fuel pressure is it slowly drops off after turning the key off. I have also replaced the distributor cap, rotor, plugs and wires. The engine seems to misfire at idle as well, and around midrange rpm, the tone through the exhaust is poppy and raspy as if the engine is leaning out. If anybody on here has a suggestion, I would sincerely appreciate it. The local Chevy dealer wants me to change my fuel pump, but the symptoms this thing is having don't make sense if it is the fuel pump (ie fuel smell after start, instant fuel pressure as soon as key is turned etc.)

  2. #2

    Default

    Are you certain the new FPR isn't leaking? If memory serves, your 454's FPR is outside the intake with a vacuum line attached to it. Run the engine, then pull that vacuum line and see if there is gas in that vacuum line (gas=bad FPR). How certain are you and the shop that all the injectors aren't leaking now?
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

  3. #3

    Default

    I would hope the new fpr isn't leaking. I used a bit of oil on the seals when I installed it, and it went in very easy. The fpr is outside the intake but getting to it is not as easy as that. to access it, the plenum has to be removed, as does the distributor cap. I will try to access the vacuum line to it without pulling it, but chances are I would have to remove it all again.

  4. #4

    Default

    Sounds like a bad FPR to me, or the spider itself is leaking.
    When you hear hoofbeats, look for horses not zebras.

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