1998 Z28 Stalls After hour Drive and hard to start

**cr0nix** · 11-25-2011, 08:12 PM

Hey everyone new to forums and had a question about my new to me z28. After about an hour of driving it will stall when its hot its worse as i am driving it feels great i will come to a random stop and the idle will flicker to 500 rpm then the car will die out i will try to restart it and it will not start unless i let it sit for a minute or 2 then start it back up then it will die again when i come to stop at high rpm runs like a dream but idle will not hold and its random and if i try to give it throttle while trying to start it just floods it to hell.I flushed the system with seafoam and bought a new air filter nothing no change error codes its spitting out is for 02 sensors do to my off road pipe but thats it so i brought it to chevy to see what they said it was they told me it was the fuel pump i went to change it today and some one had already cut the door panel in the trunk and replaced it with a brand new walbro and the fuel filter is brand new as well so the last owner tried to fix this problem and couldn't its a great car trying to find out what it may be was thinking it may be the IAC but wld it still give me issues if i was giving it throttle while trying to start it?Any help or insight to this issues wld be appreciated thanks.

**matt evans** · 11-25-2011, 09:43 PM

Might be your crankshaft position sensor fixing to shit on you. mine when it would get hot would shut the car down and take about an hour to crank back. $50 part and about 15 min work. advance usually keeps them in stock.

**pajeff02** · 11-26-2011, 03:16 AM

^^ Could very well be this. However, before you go swapping out parts -- let's do some diagnostics. Did you check fuel pressure? You should have around 58 psi at the rail. Did you scan it for codes recently, including pending codes? I understand that your SES light is on due to your ORY, however, codes can be set at any time. Also, pending codes will show a fault that is in process that has not yet caused the SES to be set until they happen two or more times within a certain number of run cycles. Is your throttle body dirty? This can cause idle issues and difficulty starting, especially if the idle air control valve is gunked up. Let us know what you find.

**SteveC** · 11-26-2011, 04:41 AM

When was the inline fuel filter replaced?

SteveC

**matt evans** · 11-26-2011, 11:06 AM

Originally Posted by pajeff02

^^ Could very well be this. However, before you go swapping out parts -- let's do some diagnostics. Did you check fuel pressure? You should have around 58 psi at the rail. Did you scan it for codes recently, including pending codes? I understand that your SES light is on due to your ORY, however, codes can be set at any time. Also, pending codes will show a fault that is in process that has not yet caused the SES to be set until they happen two or more times within a certain number of run cycles. Is your throttle body dirty? This can cause idle issues and difficulty starting, especially if the idle air control valve is gunked up. Let us know what you find.

In all my expierence so far with my ORX i removed the cats and just put the rear o2s back in line and ive not had a SES light come on at all and i check it regualry for pending o2 codes. Crankshaft position center wont throw any codes to the CPU, least in my expierence it didnt.

**cr0nix** · 11-27-2011, 02:31 PM

Thanks for all your replies every piece of the puzzle u guys find helps me out more lol need to get this thing sorted out so i can use it to go to work killin me.My 02 sensor code is on due to the last guy cutting the 02 sensor lines and just plugging in the 02 sensors to patch the holes not sure what he was thinking lol gonna fix that when i get the simulators .i have done the codes a hundred times even while car is doing its stalling performance all returned is only 02 sensor errors.I just replaced the fuel filter and fuel pump even though last guy tried to fix it this way obviously due to his hack job in the trunk tin snips not the way to go on that BTW i would always use a grinder or cutting wheel cause now i have to clean up his wonderful work.Have to wait for replacement out line for fuel tank damn O rings fell apart then i will know if fuel pump fixed it i doubt it though..Its probably the CPS or the Ignition Relay i would think because on the freeway it screams even while its having stalling issues at idle i would think fuel pump would hesitate when ur ripping on it at high speed never seen one only die at idle and be completely random but stranger stuff has happened.