Warm hard start.
Thread Starter
Advanced
Joined: Jan 2015
Posts: 57
Likes: 1
Warm hard start.
Hey guys having a hard start issue, when the car is dead cold it will fire on the first hit. When I turn the car off (been driving its completely warmed up) and walk away for 5 or 10 minutes it will fire right up on the first try............let it set for 20 minutes to 5 hours I have to crank it a couple of times and push the gas pedal almost to the floor and then it will sputter and then start. No fuel in the vac. lines and I did a fuel pressure test and it does hold when cold...warm or hot.
The car is all original, has set for a long time. However I have no codes and the car runs perfect in all other areas.
Thanks !!!!
Brian
The car is all original, has set for a long time. However I have no codes and the car runs perfect in all other areas.
Thanks !!!!
Brian
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Not the coil. Here is the key:
Leaking injector(s). When it sits for a while, fuel leaks into the intake, "Flooding" it. The WOT helps clear the flooded situation (ECM has programming for "clear flood mode" whne WOT and cranking) and expedites starting the car. You need new injectors.
Most common way to test this is to check for fuel pressure drop as you have done, however, very little fuel leakage is necessary to flood it and that small leakage may not show.
Another way to test would be to run it 'til hot, then shut it off, and drain the fuel rails w/your fuel pressure tester immediately after shut down. Wait the 20 min + and then prime the fuel systems, and see if it fires right up.
When I turn the car off (been driving its completely warmed up) and walk away for 5 or 10 minutes it will fire right up on the first try............let it set for 20 minutes to 5 hours I have to crank it a couple of times and push the gas pedal almost to the floor and then it will sputter and then start.
Most common way to test this is to check for fuel pressure drop as you have done, however, very little fuel leakage is necessary to flood it and that small leakage may not show.
Another way to test would be to run it 'til hot, then shut it off, and drain the fuel rails w/your fuel pressure tester immediately after shut down. Wait the 20 min + and then prime the fuel systems, and see if it fires right up.
Safety Car
Joined: Sep 2001
Posts: 4,153
Likes: 553
From: Glenbeulah Wi
Not the coil. Here is the key:
Leaking injector(s). When it sits for a while, fuel leaks into the intake, "Flooding" it. The WOT helps clear the flooded situation (ECM has programming for "clear flood mode" whne WOT and cranking) and expedites starting the car. You need new injectors.
Most common way to test this is to check for fuel pressure drop as you have done, however, very little fuel leakage is necessary to flood it and that small leakage may not show.
Another way to test would be to run it 'til hot, then shut it off, and drain the fuel rails w/your fuel pressure tester immediately after shut down. Wait the 20 min + and then prime the fuel systems, and see if it fires right up.
Leaking injector(s). When it sits for a while, fuel leaks into the intake, "Flooding" it. The WOT helps clear the flooded situation (ECM has programming for "clear flood mode" whne WOT and cranking) and expedites starting the car. You need new injectors.
Most common way to test this is to check for fuel pressure drop as you have done, however, very little fuel leakage is necessary to flood it and that small leakage may not show.
Another way to test would be to run it 'til hot, then shut it off, and drain the fuel rails w/your fuel pressure tester immediately after shut down. Wait the 20 min + and then prime the fuel systems, and see if it fires right up.
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
this can also be a symptom of the coolant temp sensor not sending to the ecm,
if it isnt sending a temp signal the ecm thinks the engine is still cold and enrichens the fuel mixture, making it hard to start a warmed up engine.
do you know how to check it ?
if it isnt sending a temp signal the ecm thinks the engine is still cold and enrichens the fuel mixture, making it hard to start a warmed up engine.
do you know how to check it ?
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
With a hot engine, the ignition control module may not function:
http://www.doityourself.com/stry/2-s...ition-module#b
http://www.doityourself.com/stry/2-s...ition-module#b
Thread Starter
Advanced
Joined: Jan 2015
Posts: 57
Likes: 1
Well I did the trick for letting the pressure of of the fuel rain and its still hard to start. There is a puff of smoke that comes out of the pipes like there is too much fuel in the chambers.
I am between the coil not firing leaving unburnt fuel in the chamber or somehow its still flooding as the fuel pump primes? The sticky part is all other times it runs Perfect
Thanks
Brian
I am between the coil not firing leaving unburnt fuel in the chamber or somehow its still flooding as the fuel pump primes? The sticky part is all other times it runs Perfect
Thanks
Brian
Thread Starter
Advanced
Joined: Jan 2015
Posts: 57
Likes: 1
Thanks for the tips............This is what I came up with. I let it run and let the fuel pressure off the rail when I turned it off and it was still just as hard to start so this is what I came up with.
Fuel Pressure readings
37lb @ Idle with the vac. line on
46lb @ Idle with Vac. line off
Engine completely shut off it bleed down
40lb at shut down
37lb 5 minutes after shut down
22lb 10 minutes after
and under 20 Lb at being off for 30 minutes.
Give me your opinion, I know when it does this there is some raw fuel in the exhaust.
Brian
Fuel Pressure readings
37lb @ Idle with the vac. line on
46lb @ Idle with Vac. line off
Engine completely shut off it bleed down
40lb at shut down
37lb 5 minutes after shut down
22lb 10 minutes after
and under 20 Lb at being off for 30 minutes.
Give me your opinion, I know when it does this there is some raw fuel in the exhaust.
Brian
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Thanks for the tips............This is what I came up with. I let it run and let the fuel pressure off the rail when I turned it off and it was still just as hard to start so this is what I came up with.
Fuel Pressure readings
37lb @ Idle with the vac. line on
46lb @ Idle with Vac. line off
Engine completely shut off it bleed down
40lb at shut down
37lb 5 minutes after shut down
22lb 10 minutes after
and under 20 Lb at being off for 30 minutes.
Give me your opinion, I know when it does this there is some raw fuel in the exhaust.
Brian
Fuel Pressure readings
37lb @ Idle with the vac. line on
46lb @ Idle with Vac. line off
Engine completely shut off it bleed down
40lb at shut down
37lb 5 minutes after shut down
22lb 10 minutes after
and under 20 Lb at being off for 30 minutes.
Give me your opinion, I know when it does this there is some raw fuel in the exhaust.
Brian
or cracked rubber line in the tank could be injectors but would check the cheaper stuff first
Last edited by antfarmer2; May 6, 2015 at 08:06 AM.
Safety Car
Joined: Sep 2001
Posts: 4,153
Likes: 553
From: Glenbeulah Wi
Thanks for the tips............This is what I came up with. I let it run and let the fuel pressure off the rail when I turned it off and it was still just as hard to start so this is what I came up with.
Fuel Pressure readings
37lb @ Idle with the vac. line on
46lb @ Idle with Vac. line off
Engine completely shut off it bleed down
40lb at shut down
37lb 5 minutes after shut down
22lb 10 minutes after
and under 20 Lb at being off for 30 minutes.
Give me your opinion, I know when it does this there is some raw fuel in the exhaust.
Brian
Fuel Pressure readings
37lb @ Idle with the vac. line on
46lb @ Idle with Vac. line off
Engine completely shut off it bleed down
40lb at shut down
37lb 5 minutes after shut down
22lb 10 minutes after
and under 20 Lb at being off for 30 minutes.
Give me your opinion, I know when it does this there is some raw fuel in the exhaust.
Brian
Your description to me sounds like leaking injectors but it is nice to confirm that before you start replacing parts.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
After you turn the engine off pull the throttle body duct off the throttle body and open the throttle body to WOT and listen for any hissing or dripping. On my car I could actually hear the injectors leaking which helped me confirm my theory of bad injectors.
Your description to me sounds like leaking injectors but it is nice to confirm that before you start replacing parts.
Your description to me sounds like leaking injectors but it is nice to confirm that before you start replacing parts.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
After you turn the engine off pull the throttle body duct off the throttle body and open the throttle body to WOT and listen for any hissing or dripping. On my car I could actually hear the injectors leaking which helped me confirm my theory of bad injectors.
Your description to me sounds like leaking injectors but it is nice to confirm that before you start replacing parts.
Your description to me sounds like leaking injectors but it is nice to confirm that before you start replacing parts.
Odd that draining fuel lines didn't eliminate the symptom, but fuel is leaking somewhere. You can also isolate the injectors by charging the system, the crimping off the fuel delivery and return lines where they are rubber/flexible. Doing that eliminates the pump/hose, and the FPR. If you're still losing pressure, only one thing it can be; injectors.