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  1. #1

    Default 99 yukon no start please help

    I have 99 Yukon vortec 5.7 with no start issues. I have good spark to plugs and 55-60 psi fuel press. At intake port I can spray start fluid in throttle body and it will bust off til it burns it off ????? I tested crank sensor getting 5-6 volts DC to yellow wire as I turn motor by hand. Help on stranded thanks so much

  2. #2

    Default

    Does the fuel pressure stay at 60 psi while cranking? If you start with starting fluid, does the pressure stay high after it starts?
    Because it starts on starting fluid, that strongly suggests a fuel delivery issue. I would probably do a more thorough test of the fuel system.
    '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

    Quote Originally Posted by MrShorty View Post
    Does the fuel pressure stay at 60 psi while cranking? If you start with starting fluid, does the pressure stay high after it starts?
    Because it starts on starting fluid, that strongly suggests a fuel delivery issue. I would probably do a more thorough test of the fuel system.
    Thanks for replying fuel pressure drops down to 40 psi while cranking.

    - - - Updated - - -

    Quote Originally Posted by MrShorty View Post
    Does the fuel pressure stay at 60 psi while cranking? If you start with starting fluid, does the pressure stay high after it starts?
    Because it starts on starting fluid, that strongly suggests a fuel delivery issue. I would probably do a more thorough test of the fuel system.
    It drops down to 40 whole cranking

  4. #4

    Default

    From what little I have seen diagnosing my own fuel system issues, these engines need 50+ psi of pressure to start/run well. Below 50 and they start to have problems. I expect once you resolve the reason the system is losing pressure, you will find the cause of your no start.

    Basically two causes for this:
    1) A bad fuel pressure regulator
    2) Something with the pump.

    Is the pump running while cranking?

    If the pump is running, what pressure is it capable of? This can be tested by carefully clamping off the return line (where it is rubber) and see what pressure is generated. If the system pressure jumps up (should probably go well above 66), that suggests that the fuel pressure regulator is opening too soon. If the pressures do not change, that suggests the pump is not able to generate enough pressure. Check for clogged filter or other kink/restriction in the supply line between the pump and the fuel spider. If the lines check out ok, then the pump itself is probably going bad.
    '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

  5. #5

    Default

    following... similar problems with my 99 Burb, 5.7...
    Some stuff with wheels and motors...

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