1998 vortec no start when cold

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by conman13, Sep 27, 2011.

  1. conman13

    conman13 New Member

    Ok when this is cold you can crank it untill the batteries die it will not start, give it a little gas down the intake and it starts right up. Every time after that it will start on the first turn of the key all day long, let it sit over night and you have to put gas down it's throat. It has good fuel good spark good grounds, two good batteries, new distributor, new wires, new plugs, new temp sensors, new starter and a completely different engine with all different sensors and fuel injection because the other engine had a little more blow by on two cyl. Thanks. 1998 K1500 Suburban.
  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Because it will start when you put a little gas in the intake suggests that the problem is a fuel delivery problem. You say it "has good fuel." How are you verifying fuel delivery when it won't start?
  3. conman13

    conman13 New Member

    On the first motor I was thinking vacuam leak so I took the lower and upper intake apart, cleaned and put back together. The fuel pressure was I think around 52-55 psi and had good volume. I also installed a relay switch so I could run the pump non stop. What has got me is how it starts great even when hot.
  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    If I may ask, was that fuel pressure measured while trying to start it when it wouldn't start?

    The next thing I'd be looking at would be the injectors. Are they firing when it won't start? Is gas getting through? Maybe pull a spark plug and see if it is "wet." If there's no indication of gas getting into the cylinders, then I would look closer at the injectors/poppet valves.
    Last edited: Sep 28, 2011
  5. conman13

    conman13 New Member

    OK when it is cranking there is 45 psi, when it is cranking I also checked and there is no injector pulse.( I checked it with a low impedence test light)
  6. janikphoto

    janikphoto Rockstar 3 Years 100 Posts

    yeah, but the injectors should be OK, since it'll run fine after your little "gas pour" fix. It seems like there is something obvious and simple here... I just haven't put my finger on it yet. A game of twenty questions should help solve this. Are you able to test an injector outside of the truck? Not sure what capability you have on hand...
  7. conman13

    conman13 New Member

    OK I just did a injector pulse test and all 8 injectors flowed the same . I did some more testing and found that the pass lock system shuts the injectors off if the capacitors give the wrong voltage or the pass lock sensor could be bad, so now I need to find the capacitors that are some place around the shift lock. Any ideas?
  8. conman13

    conman13 New Member

    Does anybody know how to relearn the passlock system? Thanks.
  9. BobEhud

    BobEhud Rockstar

    ck your fuel pressure regulator,that is supposed keep pressure at the rail so it fires right up.Small round item should be on drivers side.Single vacuum hose coming out if you pull that hose and smell gas you have your gremlin.Oh and they are easy to change and cost very little.

    45lbs is low for that truck KOEO should be closer to 60psi.But that again could be the regulator.
  10. conman13

    conman13 New Member

    I put 13 volts straight to the fuel pump and got 58 psi when cranking and still did not start and still had no injector pulse, but here is another piece of the puzzle, last night I plugged in the block heater and this morning it started right up.

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