hard starts when hot along with a miss 2001 silverado?

[CKENDZIORA]

Ok guys this is a long story but i swappped the fuel pump with a Delphi unit per this forum due to irratic fuel gauge issues. However i also have issues with hard starts when theengine is hot and the RPM at idle drops to 500 RPM along with a miss. The code scanner shows Misc misfire along with o2 sensors the truck runs real rich at start when warm? I have changed the plugs, wires and fuel filter also. Were do i start? Cold the engine runs fine once warm its a bugger to start and runs like crap real flat on acceleration etc.... this truck is 2001 silverado with a 5.3l with 109000 miles

[Tdragone]

So.... If the codes thrown are for the o2 sensors... have you changed THEM?

[CKENDZIORA]

issue is/was my son did the code reading and didnt remeber which sensors as there are 4 on the truck I'm not about to change them all as I have changed the 2 downstream one in the last year? does the symptom point to o2 sensors?

[j cAT]

Originally Posted by CKENDZIORA

issue is/was my son did the code reading and didnt remeber which sensors as there are 4 on the truck I'm not about to change them all as I have changed the 2 downstream one in the last year? does the symptom point to o2 sensors?

the upstream sensors are the ones to change if they are bad. these report the fuel / exhaust mixture to computer.

the fuel regulator and injectors may be bad. replace the fuel regulator not too expensive. also due the fuel pressure leak down test engine on record pressure engine off see how long it takes to drop. if it drops to fast then this in your case may indicate it is the fuel regulator diaphram or leaky injectors flooding the engine.

[CKENDZIORA]

Originally Posted by j cAT

the upstream sensors are the ones to change if they are bad. these report the fuel / exhaust mixture to computer.

the fuel regulator and injectors may be bad. replace the fuel regulator not too expensive. also due the fuel pressure leak down test engine on record pressure engine off see how long it takes to drop. if it drops to fast then this in your case may indicate it is the fuel regulator diaphram or leaky injectors flooding the engine.

when you start the truck after sitting or when hot it belches black smoke. this has happened slowly over time if that gives us some clues?

[j cAT]

Originally Posted by CKENDZIORA

when you start the truck after sitting or when hot it belches black smoke. this has happened slowly over time if that gives us some clues?

yes this is what happens when the fuel regulator ruptures or the injectors are leaking.

for you It will be much cheaper if it is the regulator diaphram...if the injector use some techron injector cleaner and add a few ounces of marvel mystery oil to the fuel ..this will clean the injectors..hopefully

[CKENDZIORA]

i am running MM and some Lucas cleaner thru it now. when I get time I will get a pressure gauge from Auto Zone and test, hopefully the new fuel pump i put in is ok...

[j cAT]

Originally Posted by CKENDZIORA

i am running MM and some Lucas cleaner thru it now. when I get time I will get a pressure gauge from Auto Zone and test, hopefully the new fuel pump i put in is ok...

fuel pump should not be a problem , the injectors or a bad regulator is..

[CKENDZIORA]

thanks ill let you know what the results are...

[CKENDZIORA]

Well it was the fuel pressure i eneded up taking it to my local garage due to time constraints. She purrs like a kitten now

[KaIIen]

This is probably too late for OP, but may help someone else reading this.... Even though the codes has been read and the Check light reset, your computer still has a record of the code. Go to O'Reily's or AutoZone (both read codes for free) and they will be able to pull the info and tell you which sensor.

[spackelman]

Originally Posted by CKENDZIORA

Well it was the fuel pressure i eneded up taking it to my local garage due to time constraints. She purrs like a kitten now

what was the problem ?