97 suburman flooding and won't start, flooding issue

Discussion in 'Chevy C/K Truck Forum' started by suburman, Jan 14, 2014.

  1. suburman

    suburman New Member

    I have a challenge for all master mechanics out there. My 5.7 Vortec starts sometimes and sometimes not. Now it won't at all. Here's what I know. Fuel pressure is 65psi KOEO and drops to 58 when cranking. Pressure drops to 20psi in 120 seconds after turning off. I removed upper manifold, and fuel spider and reconnected the fuel lines and harness and turned key on. Exact results as above (including pressure drop to 20 psi)without a drop of fuel leaking from any injector, poppet, or regulator. Fuel pres regulator is 6 months old and pump is about 1-1/2 years old. Strong smell of fuel when trying to crank. I capped off the fuel supply line at the meter and turned on key. Pressure goes to 85 psi and then drops to 20 psi in about 30 seconds. Removed #2 and #8 plug and have strong spark at both. Starting fluid does nothing. After attempting to start, plugs #2 and 8 were soaked. Clearly, I have a flooding problem, but can't figure out why. It has same symptoms as when the regulator went bad 6 months ago but everything under the manifold looked good except slight fuel wetness in rear half. Only DTC codes are a cyl 4 misfire and a couple of O2 sensor codes that have been there forever. Only other clue is that when I turn the key back from start to "on" after trying to crank, the engine diesels for a second like it's trying to fire but can't quite get there. I can't figure out why it's flooding when nothing is leaking from the poppets. As a follow-up I went out during cold weather the other day and it cranked up like brand new. Let it sit a couple of days and no start again. Flooding and strong smell of fuel have accompanied every failed starting attempt. Any suggestions are appreciated.
  2. Jamm3r

    Jamm3r Member 2 Years 100 Posts

    I would suspect a fuel pressure regulator that does not regulate

    Excessive pressure to the spider leading to rich mixture

    Wouldn't be the first time a fuel pressure regulator was toast after 6 months
  3. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Leaky injector, maybe??
  4. edsmagichands

    edsmagichands Member 2 Years 100 Posts

    Hopefully you've found your problem by now, but if not, i have some suggestions for you. my first rule of diagnostics is " don't start a complicated diagnosis without first verifying the basics!" it's very common and will cause a lot of hair pulling and wasted time. that being said, you state " Removed #2 and #8 plug and have strong spark at both", however you do not say how you determined "strong spark". also what is the condition of the basic ignition system? IE: cap, rotor, wires, spark plugs & their gap. any carbon tracking on the porcelain part of the plugs? what about the coil? i have solved many no starts that appeared to have good spark & seem to be flooding simply by doing the basics, plugs, ign wires, cap & rotor. if the spark is not hot enough, no start with fuel smell will result. be SURE! the basics are good. OK, now see if it starts with the MAF sensor unplugged. bad/dirty MAF sensor could cause PCM to increase inj pulse width adding too much fuel. if you unplug it, PCM should supply a default value to allow car to start. also often overlooked is the coolant temp sensor. not the sender for the gauge, the one for the PCM. a bad sensor can cause the PCM to think it's -40 degrees and it will add unneeded fuel. check the wiring & connectors at both sensors. if you have access to a scanner, check data stream values for them. let me know what happens, good luck!
  5. 88k2500

    88k2500 Member

    I agree with the above. He knows what he is talking about.
  6. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    great Post!!

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