Hard to start when warmed up

Asked by Apr 07, 2016 at 04:36 PM

Question type: Maintenance & Repair

Have a 98 Tahoe 5.7 4x4, when I start it
cold it starts without hesitation, when it
gets to normal operating temp and I turn it
off it won't start unless I hold throttle to the
floor. When it does start, it's very rough,
fluctuating between higher than normal idle
and stall. I have to keep revving it up to
keep it running. I had read some blogs and
they all said the fuel pressure regulator,
which I replaced, as well as the pressure
sensor on the top of the intake plenum. Put
it all back together with new gaskets and it
still does the same thing. Any suggestions
would be great thanks

3 Answers

28,045

i would run a bottle of ZMAX.... fuel treatment thru it first....also,The mass airflow sensor is another important piece of the puzzle, even though it is commonly overlooked. It measures the engine’s air flow and sends that information to the engine’s computer, which then regulates fuel injection, the ignition system and transmission shifting. When it gets dirty or becomes faulty, it can cause a multitude of issues such as an engine that is difficult to start, engine stalling after startup, hesitation or jerkiness during acceleration and unusually lean or rich idling.

76,265

Well you say it starts up and runs good when it is cold, so I would have the Ignition Control Module & the coil tested at Auto Zone, but you would have to take them out to be tested. It could be when the engine heats up that it is affecting these items, and will if there bad. Also, it wouldn't hurt to check the fuel pressure, it should be 56 to 63 lbs. Then at the same time turn the key to off and watch the fuel pressure gauge. It should not drop more than 5 lbs in 3 minutes. If it does you still have a problem with the spider injection. It is recommended to replace it all as a hole unit, not piece by piece.

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