Cold Starting Issues - maybe fuel related?

Discussion in 'Chevy C/K Truck Forum' started by JWhit, Feb 13, 2012.

  1. JWhit

    JWhit New Member

    Having a hard time diagnosing the starting issues on my 98 5.7 silverado. when the engine is cold, it takes a while to start and usually only works on a quick turn of the key after a few attempts. last year i did a tune up of plugs, wires, cap, rotor, fuel filter, battery. of course suspected the fuel pump, so got a gauge and on the first turn of the key pressure gets to right around 60, give or take 1-2 depending on temp. if I cycle a few more times before starting, can get to 63 or so, but even at that point doesn't fire right up and takes a few attempts. anybody else had this issue? once warm it starts back up pretty quick. not sure of the most common sensor issues or regulator possibilities, or if it's usually the pump, thanks for any advice!

    ---------- Post added at 09:52 AM ---------- Previous post was at 09:47 AM ----------

    also forgot to mention, had a friend with a shop scanner take a look and he said everything checked out, no CEL or codes to pull. also the pressure does drop slightly over time once the pump stops, but less than 1 psi per minute.
  2. Scott_Anderson

    Scott_Anderson Rockstar 100 Posts

    1st thought that comes to my mind would be the engine coolant temp sensor.

    Either one of two faults 1: It's thinking the engine is warmer than it acutally is so it's not giving enough fuel for a cold start, or
    2: It's thinking the engine is colder than it actually is so it's giving too much fuel for a cold start.
    Since you are able to start ok once the engine is warm, I'm thinking more towards the 1st fault.
    Have your friend plug his scanner in again and see if he can read the "ect" sensor and see what it's reading.

    There could be other issues, but this is my thougt.
  3. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    I second that above post, and or else the fuel pressure regulator is dumping raw fuel into the intake (common issue with the 5.7L vortec) and when the motor is cold the fuel is puddled up causing it to basically flood, as well as not allowing the injectors to get the correct pressure.
  4. fishman350

    fishman350 New Member

    yes i 3rd it. i had the same problem,mines flooded.The connection was bad at the engine coolant sensor(located by your thermostat,just under it i think).i took the connector off and carefully put it on right and it fired right up.
  5. JWhit

    JWhit New Member

    So I had him scan again, and no luck. i'll try to manually clean that contact to see if that helps, but have run into other issues now. On Saturday I used the truck all morning, no issue starting other than the first time, and filled it with gas on the way home. A few hours later, wouldn't start at all. Took a pressure reading and got only 52 max psi after cycling the pump a few times. When i dumped a little gas in the throttle body, i was able to get it to start and stay running - but the next day same thing. Does this mean the pump most likely? Got the bolts out of the bed, planning to remove soon to at least look at the pump for any blockage or loose wiring

    ---------- Post added at 08:48 AM ---------- Previous post was at 08:46 AM ----------

    Thanks for the advice guys, i'll try to clean the ECT connection and is there an easy way to test the FPR other than installing valve in return line?
  6. JWhit

    JWhit New Member

    Well in case anyone has the same problems, I ended up replacing the fuel pump after other tests for FPR showed no results. New fuel pump has me up and running, and starting quickly. Hopefully no more issues!

    Also I removed the bed, and am glad I did
    1 person likes this.
  7. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Thanks for the update.. and sadly i did not reread this post but for future reference you have a schrader valve up on the intake for testing the fuel pressure on the Vortec motors. This allows you to check the inlet pressure (should be 55-60PSI min of 58PSI to start) and check the FPR once the key is off if it hold pressure fairily steady as time goes on (a little drop is normal) then that is not your problem.. Glad you got it all taken care of!
  8. 08_rado_rocker

    08_rado_rocker Member 2 Years 500 Posts

    I know it's a little off subject, but you made me curious.. why do you say you're glad you removed the bed?
  9. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    I am actually gonna answer that one LOL... Removing the bed is much easier than dropping the tank.. there is less of a chance of breaking something and you are working standing up rather than on your back. just ALOT less messing around

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