[Z06] Hard starting issue 03 z06
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
Hard starting issue 03 z06
I picked up a 03 z06 few weeks ago with 12,xxx miles on it. I noticed that the car has a hard starting issue but only when its been sitting.
example... park go in store come out 45 min later turn key it cranks for a while then starts.
but now if i shut it then restart it cranks and starts instantly.
im thinking possible fuel filter is clogged ?
but not sure definitely looking for some advice / suggestions.
I tested the battery and it was bad so I put a new one in, so its not the battery.
thanks in advance
example... park go in store come out 45 min later turn key it cranks for a while then starts.
but now if i shut it then restart it cranks and starts instantly.
im thinking possible fuel filter is clogged ?
but not sure definitely looking for some advice / suggestions.
I tested the battery and it was bad so I put a new one in, so its not the battery.
thanks in advance
Advanced
Joined: Sep 2006
Posts: 51
Likes: 0
From: Dallas Texas
What color did you get? I too just recently picked up a 03 Z06, a Quicksilver with 22,xxx miles on it. It's funny to see this thread because I was thinking my car was doing the same thing. I haven't checked my battery yet though but my acc's work and windows roll up good with car off. Is your car stock? I doubt it is the fuel filter, unless you're feeling the car struggle for gas during driving or at times during driving, not just during start up. I've been turing the key "on" for a couple seconds and let the fuel pump do its thing, then crank it over. I don't know if it took care of the cranking entirely, but I think it did somewhat. Good luck.
J
J
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
put a fuel pressure gauge on the rain, start the car, verify pressure, shut the car off and see how long it takes to bleed down
next, have a friend start the car while you watch the gauge.
if you're loosing pressure fast and or it's not building for start up leaking injectors are suspect
next, have a friend start the car while you watch the gauge.
if you're loosing pressure fast and or it's not building for start up leaking injectors are suspect
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
What color did you get? I too just recently picked up a 03 Z06, a Quicksilver with 22,xxx miles on it. It's funny to see this thread because I was thinking my car was doing the same thing. I haven't checked my battery yet though but my acc's work and windows roll up good with car off. Is your car stock? I doubt it is the fuel filter, unless you're feeling the car struggle for gas during driving or at times during driving, not just during start up. I've been turing the key "on" for a couple seconds and let the fuel pump do its thing, then crank it over. I don't know if it took care of the cranking entirely, but I think it did somewhat. Good luck.
J
J
If it was the injector o-rings I feel like I would smell raw fuel in the engine compt.
put a fuel pressure gauge on the rain, start the car, verify pressure, shut the car off and see how long it takes to bleed down
next, have a friend start the car while you watch the gauge.
if you're loosing pressure fast and or it's not building for start up leaking injectors are suspect
next, have a friend start the car while you watch the gauge.
if you're loosing pressure fast and or it's not building for start up leaking injectors are suspect
i just find the whole situation odd because like i said if i shut it then start it again it starts instantly. but if i walk away for 20-30 mins it cranks mad hard.
However, after doing some VIN specific research it appears as if I do have an external fuel filter so if that is the case I will swap that out anyway as it is a cheap, easy maitenence move.
I also do hear the fuel pump prime every time I turn the key so I doubt that the pump is the issue.
To be honest most people would probably deal with the hard start but im hardcore anl about stuff like this
Im also going to clean the throttle body out and check the sensors around it. Could possibly be tied to that as well but it seems like it is a fuel issue.
on a side note took it to the track and did 12.8 first pass on street tires not bad lol
Last edited by 6spdg37s; Jun 6, 2013 at 08:09 AM.
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
Change the fuel filter--There is a line from the filter to the tank--this line has a check valve--it keeps the pressure up to start the car--the valve could be stuck open allowing the fuel to drain back into the tank-If you have to crank the car twice and it starts the second time--it could very be that line--check with your GM service dept. about this fuel line-
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
Change the fuel filter--There is a line from the filter to the tank--this line has a check valve--it keeps the pressure up to start the car--the valve could be stuck open allowing the fuel to drain back into the tank-If you have to crank the car twice and it starts the second time--it could very be that line--check with your GM service dept. about this fuel line-
But I will look into the line, is there a way to tell if the check valve is stuck open?
Burning Brakes
Joined: Aug 2006
Posts: 887
Likes: 15
From: Central CT
St. Jude Donor '16
I've had the same issue on one of my previous Z06s a few years back. After changing the filter and looking through all the fuel lines and hoses, it ended up being the check valve. I honestly don't remember exactly where it was located, but I think It was on top of one of the fuel tanks, or somewhere in the back. I did mine myself but had access to a lift. Good luck and hope you get it fixed!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
I've had the same issue on one of my previous Z06s a few years back. After changing the filter and looking through all the fuel lines and hoses, it ended up being the check valve. I honestly don't remember exactly where it was located, but I think It was on top of one of the fuel tanks, or somewhere in the back. I did mine myself but had access to a lift. Good luck and hope you get it fixed!
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
I've had the same issue on one of my previous Z06s a few years back. After changing the filter and looking through all the fuel lines and hoses, it ended up being the check valve. I honestly don't remember exactly where it was located, but I think It was on top of one of the fuel tanks, or somewhere in the back. I did mine myself but had access to a lift. Good luck and hope you get it fixed!
Last edited by bobby777; Jun 6, 2013 at 10:19 AM. Reason: add
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
The check valve is located in one of the fuel lines--I had that problem but mine is a 01 Z06-maybe the 03 is different-so if you call the parts dept or service and talk to someone who would know about this- if I remember its about a 1/4 inch line--NO way to tell if its stuck open--but it sure sounds like it top me--DOES the car start right up on the 2nd crank?
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
Or is there a simple check valve delete? in other words picking up a filter that does not have the check line spot ? like a Wix or a DELCO without it?
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
either way should I do the filter as well ? I feel like the filter is a common maitenence item that should be done. remembering that the car is 11 years old assuming it had a late 02 build date which is what I believe if I recall correctly.
Or is there a simple check valve delete? in other words picking up a filter that does not have the check line spot ? like a Wix or a DELCO without it?
Or is there a simple check valve delete? in other words picking up a filter that does not have the check line spot ? like a Wix or a DELCO without it?
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
they did the switch MID 2003 MY . so according to the VIN cutoff I read I have the external filter. Also if the filter was internal there would be no more hose with a check valve in it and I probably wouldn't be having these problems lol
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
I been in touch with a friend who is a advisor at a GM dealer few states away. .
they did the switch MID 2003 MY . so according to the VIN cutoff I read I have the external filter. Also if the filter was internal there would be no more hose with a check valve in it and I probably wouldn't be having these problems lol
they did the switch MID 2003 MY . so according to the VIN cutoff I read I have the external filter. Also if the filter was internal there would be no more hose with a check valve in it and I probably wouldn't be having these problems lol
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
where did you purchase the line with the check valve in it/what is it called? so i can try to find this
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
Thread Starter
Drifting
Joined: Oct 2008
Posts: 1,793
Likes: 63
From: Staten Island/NJ NY/NJ
only update I have thus far is that supposidly you can not buy the check valve without buying the whole tank assembly so that is $2,250 bucks. I am not doing that. I am thinking/ hoping that it is a even simpler fix and is the result of a clogged fuel filter. It seems like the check valve might not cause this problem. But a clogged fuel filter could most definitely cause this problem as it is taking longer to build the fuel pressure at the fuel rail because the cloggingness (sp?) is causing the fuel to flow slower. When you turn it off and start it right away again the fuel pressure is still built up from the car running.