Hard start when hot
Thread Starter
Pro
Joined: Aug 2019
Posts: 596
Likes: 146
From: Minford, Ohio
Hard start when hot
I have a problem with my 93 LT1 with 17,000 miles. I just bought the car last August and haven't driven it much but here's the problem. When cold it starts within 1 revolution, super quick. After it reaches operating temperature and you shut it off it will restart fine for up to 15 minutes, after that you have to crank for 4 or 5 seconds before it will start unless you push down on the accelerator. It doesn't matter if you just push it a little or all the way to the floor it will start instantly. I sent the injectors to FIC and had them cleaned and that didn't change anything. Fuel pressure drops normally and is zero the next morning but will start instantly. My thought is they are leaking but I waited for a half-hour and pulled them out with the fuel rail and set them on brown paper, turned on the key to get the pressure up to 43 psi and saw no sign of gas leaking out of them. At this point, I have no idea what the problem is. Does anyone out there have any idea what's wrong? It always runs perfectly and idles perfectly after it's started.
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
My 93 does the same thing starts quickly but when hot cranks a little slower and it has 16,000 miles on it and i bought it new. Only item i ever changed was opti and the water pump which you could not turn shaft with water pump pliers (frozen in place) and never threw a code.My car is garaged and looks like it came out of a detail shop so beware of any odd doings for the OB1 is not a reliabel source of which way to head when odd items start to react odd in the daily operations of the car
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
I would drive it with the hood but unlatched with the fuel pressure gauge on the windshield. Also, check code and see if you have any, I don’t like to guess, but with age and low miles, could have insect build up in evap system , fuel pump gets hot and looses effective pressure , and then ignition control module going bad ad or die electric grease behind it dryer out. Could also be injectors as you said, if original, they likely would benefit regardless of a bench check and cleaning.
Safety Car
Joined: Jan 2012
Posts: 3,953
Likes: 520
From: Da U.P.
Are they different than the Camaro/454 L29 injectors? Because there are a couple of cleaners who won't touch them. Supposedly the insulation gets washed off the coils inside and basically shorts them out.
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
Safety Car
Joined: Jan 2012
Posts: 3,953
Likes: 520
From: Da U.P.
Search the forum, there are multiple places
https://fuelinjectorconnection.com/c...ration-service
https://fuelinjectorconnection.com/c...ration-service
https://www.witchhunter.com/probleminj1.php
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Thread Starter
Pro
Joined: Aug 2019
Posts: 596
Likes: 146
From: Minford, Ohio
I sent them to FIC and they cleaned them but it did not help my problem. Something is not working right when it gets hot but I don't know what it is. The strange part is, if I just open the throttle a little bit it starts fine like it should.
Safety Car
Joined: Jan 2012
Posts: 3,953
Likes: 520
From: Da U.P.
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
SloJo, FIC normally sends you a report for each injector. If it cranks hot with your gas pedal to the floor, it sounds like a flooding issue, there are ways to trouble shoot this. Your fuel rail comes off very easy, you can check any leaking injectors. I still go back to the basics I posted earlier. I really sounds like a fuel pump issue with the check valve or regulator when hot, I lean toward fuel pump but I don't recommend replacing any parts without a proper diagnostic. Please try the fuel pressure gauge on windshield from cold to start to after driving for a while.
Good suggestions have been made. Please do not flame or hijack another persons thread. There are plenty of Camaro forums, I know Corvettes, yes, some parts are the same some are not, my help is intended for Corvettes only.
Good suggestions have been made. Please do not flame or hijack another persons thread. There are plenty of Camaro forums, I know Corvettes, yes, some parts are the same some are not, my help is intended for Corvettes only.
Last edited by corvette95; Mar 12, 2020 at 08:32 AM.
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
First item remove old fuel and buy the best name brand fuel 93. ( A station with a lot of traffic is best because they rotate stock frequently) Next fuel filter ( GM Brand) Next let it idle till the second fan comes on you want to be in closed loop.If a hesitation is felt as you rev it in neutral (or sputtering) Look at thr Opti that is the heart of that beast! My car has never been to a dealer ever, and i have survived many storms! Good Luck!
Safety Car
Joined: Jan 2012
Posts: 3,953
Likes: 520
From: Da U.P.
SloJo, FIC normally sends you a report for each injector. If it cranks hot with your gas pedal to the floor, it sounds like a flooding issue, there are ways to trouble shoot this. Your fuel rail comes off very easy, you can check any leaking injectors. I still go back to the basics I posted earlier. I really sounds like a fuel pump issue with the check valve or regulator when hot, I lean toward fuel pump but I don't recommend replacing any parts without a proper diagnostic. Please try the fuel pressure gauge on windshield from cold to start to after driving for a while.
Good suggestions have been made. Please do not flame or hijack another persons thread. There are plenty of Camaro forums, I know Corvettes, yes, some parts are the same some are not, my help is intended for Corvettes only.
Good suggestions have been made. Please do not flame or hijack another persons thread. There are plenty of Camaro forums, I know Corvettes, yes, some parts are the same some are not, my help is intended for Corvettes only.
Thread Starter
Pro
Joined: Aug 2019
Posts: 596
Likes: 146
From: Minford, Ohio
Thank you all for your suggestions. I have replaced the fuel filter. Other than this one little quirk the car runs great. I don't have to floor the gas pedal to make it start if I just barely push it open it will start normally. I've run several tanks of gas thru it and all we have here in Southern Ohio is 93 octane. Again, once the car is started it runs great, no misses, no hesitations, good smooth idle. Just this one little quirk!
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
Just a thought....the only thing you've changed by moving the pedal is allowing more air into the motor. Is your IAC working correctly? I would check it for operation as well as for carbon build up. When you start it cold, does it idle high for a minute or two, then idle down slowly?
The other item to check is the throttle body/plate carboned up also. If the clearance between the throttle plate and the throat is blocked with carbon, that will affect your hot starting.
The other item to check is the throttle body/plate carboned up also. If the clearance between the throttle plate and the throat is blocked with carbon, that will affect your hot starting.
Last edited by Mrvettenick; Mar 12, 2020 at 12:00 PM.
Team Owner
Joined: Jul 2004
Posts: 28,330
Likes: 3,245
From: Hartford WI
Just a thought....the only thing you've changed by moving the pedal is allowing more air into the motor. Is your IAC working correctly? I would check it for operation as well as for carbon build up. When you start it cold, does it idle high for a minute or two, then idle down slowly?
The other item to check is the throttle body/plate carboned up also. If the clearance between the throttle plate and the throat is blocked with carbon, that will affect your hot starting.
The other item to check is the throttle body/plate carboned up also. If the clearance between the throttle plate and the throat is blocked with carbon, that will affect your hot starting.
As to the CTS, why don't we check what it is doing? Scan the thing and hit it with an IR Thermometer? If they aren't close, there could be a problem. So if it thinks the temp is 200 when it is 120, perhaps the fueling is changed? Doesn't hurt to hook up a scanner and hit the sensor with a thermometer to verify that they are right.
Thread Starter
Pro
Joined: Aug 2019
Posts: 596
Likes: 146
From: Minford, Ohio
Just a thought....the only thing you've changed by moving the pedal is allowing more air into the motor. Is your IAC working correctly? I would check it for operation as well as for carbon build-up. When you start it cold, does it idle high for a minute or two, then idle down slowly?
The other item to check is the throttle body/plate carboned up also. If the clearance between the throttle plate and the throat is blocked with carbon, that will affect your hot starting.
The other item to check is the throttle body/plate carboned up also. If the clearance between the throttle plate and the throat is blocked with carbon, that will affect your hot starting.