Hard to start when hot???
Thread Starter
On The Tree
Joined: Jul 2008
Posts: 129
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Hard to start when hot??? I'm having an issue with my 02 TA that when cold, the car fires right up, but once it gets hot, and I stop at the store lets say, I have to crank and crank. It won't start until I cycle the key off, and back to crank, and then it wil start. Reminds me of trying to start a older carburated car. WTF? any ideas? changed plugs, the originals that were in it seemed a dirty brown, gaps were .060-.065 and they were the oem. Also changed fuel filter with a fram. Car has only 67k.
Joined: Nov 2001
Posts: 34,638
Likes: 2,564
From: Schiller Park, ILL Member: #317
If it is cranking properly when you try to start it, but just won't fire, then the issue is not the starter or the charging system.
I imagine that the issue is fuel or spark related, more likely fuel since it seems to start once you re-prime the system by cycling the key all the way off and on again. Sounds like you have covered the basics with new plugs and new fuel filter, so next thing I would check would be fuel pressure under the conditions that cause the problem.
I imagine that the issue is fuel or spark related, more likely fuel since it seems to start once you re-prime the system by cycling the key all the way off and on again. Sounds like you have covered the basics with new plugs and new fuel filter, so next thing I would check would be fuel pressure under the conditions that cause the problem.
IAT heat soak is an easy way to mess the mixture and
timing. Especially if you're still running stock fan settings
and haven't cleaned your radiator in a decade, it gets
a tad warm underhood.
IAT out of the engine bay is a good idea.
timing. Especially if you're still running stock fan settings
and haven't cleaned your radiator in a decade, it gets
a tad warm underhood.
IAT out of the engine bay is a good idea.
Thread Starter
On The Tree
Joined: Jul 2008
Posts: 129
Likes: 0
Starter works fine. Didn't think about IAT, radiator is clean as can be. Car has original thermo, temp reaches about 190 on guage. We were thinking of fuel pump, and or regulator as well? How and were would you relocate IAT?
Joined: Nov 2001
Posts: 34,638
Likes: 2,564
From: Schiller Park, ILL Member: #317
I think that IAT location seems doubtful as the culprit, since you wouldn't be seeing any significant IAT cool-off in those few seconds that it takes to clear the condition with a key cycle. Sounds to me like the pump re-prime is what's helping here. Therefore, I'd still look at the fuel system (pump, pressure) as a starting point based on your description of the symptoms.
It certainly wouldn't hurt to optimize the IAT location, but mine is still in it's stock position and it doesn't cause any starting issues even on 90-100° days with 100k+ miles/10+ years of age and a stock cooling system/stock fan settings.
It certainly wouldn't hurt to optimize the IAT location, but mine is still in it's stock position and it doesn't cause any starting issues even on 90-100° days with 100k+ miles/10+ years of age and a stock cooling system/stock fan settings.
Last edited by RPM WS6; Feb 13, 2013 at 11:27 PM.
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If it sits for a bit and becomes hard to start, it could be a leaking injector.
Next time you park it and you have a feeling that it'll do it again, try this.
Throttle position over 80% puts the ECM in Clear Flood Mode. Meaning it will shut off injectors so you can crank it over without spraying fuel into the combustion chamber.
so put the pedal to the floor and crank it over, it it fires right up, you know you've got a fueling issue (more than likely a leaking injector causing a very rich mixture)
Next time you park it and you have a feeling that it'll do it again, try this.
Throttle position over 80% puts the ECM in Clear Flood Mode. Meaning it will shut off injectors so you can crank it over without spraying fuel into the combustion chamber.
so put the pedal to the floor and crank it over, it it fires right up, you know you've got a fueling issue (more than likely a leaking injector causing a very rich mixture)
If it sits for a bit and becomes hard to start, it could be a leaking injector.
Next time you park it and you have a feeling that it'll do it again, try this.
Throttle position over 80% puts the ECM in Clear Flood Mode. Meaning it will shut off injectors so you can crank it over without spraying fuel into the combustion chamber.
so put the pedal to the floor and crank it over, it it fires right up, you know you've got a fueling issue (more than likely a leaking injector causing a very rich mixture)
Next time you park it and you have a feeling that it'll do it again, try this.
Throttle position over 80% puts the ECM in Clear Flood Mode. Meaning it will shut off injectors so you can crank it over without spraying fuel into the combustion chamber.
so put the pedal to the floor and crank it over, it it fires right up, you know you've got a fueling issue (more than likely a leaking injector causing a very rich mixture)
Thats some good geewiz info!
If it sits for a bit and becomes hard to start, it could be a leaking injector.
Next time you park it and you have a feeling that it'll do it again, try this.
Throttle position over 80% puts the ECM in Clear Flood Mode. Meaning it will shut off injectors so you can crank it over without spraying fuel into the combustion chamber.
so put the pedal to the floor and crank it over, it it fires right up, you know you've got a fueling issue (more than likely a leaking injector causing a very rich mixture)
Next time you park it and you have a feeling that it'll do it again, try this.
Throttle position over 80% puts the ECM in Clear Flood Mode. Meaning it will shut off injectors so you can crank it over without spraying fuel into the combustion chamber.
so put the pedal to the floor and crank it over, it it fires right up, you know you've got a fueling issue (more than likely a leaking injector causing a very rich mixture)
If the above does not work then you may have a lean condition, where the fuel pressure may bleed back down into the fuel tank. It is my understanding that there is a check valve either in or with the fuel pump.
Try this, instead of turning the ignition to the start position, just turn the ignition on, count to five, then to start. This would give the fuel pump time to pressure the fuel rails and injectors. If you start right up, then you may have a fuel pump problem. BTW, it should be noted that a pressure gauge should be connect to the fuel rail while you are troubleshooting your vehicle.
It has been my observation that no one resolves this issue or they do not post the corrective action...these threads just stop! If you corrected a malfunction, please share the fix...
TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
I'm another voting for diagnosis.
Hook up fuel pressure gauge. Check pressure. You should have 4 bar (roughly 60 PSI). If it's less than that you have a weak pump. If it jumps to that then bleeds down within seconds you have a check ball or regulator problem. They all reside in the fuel tank.
Your issue is very likely fuel related.
On a related note, did you recently install headers?
Also, don't relocate your IAT sensor. People who recommend this don't know how it's location effects your cars calculated DA. Relocating it tells it that the air is cooler, therefore denser, and it gives it more fuel. But this doesn't mean increased power, it can, but typically it LOOSES power by doing this. Our vehicles already run rich from the factory, making the car think the air is cooler than it's factory calibrated location makes it run even richer. It's all moot anyway I guess cause the O2's will trim it back to stoich anyway.
Hook up fuel pressure gauge. Check pressure. You should have 4 bar (roughly 60 PSI). If it's less than that you have a weak pump. If it jumps to that then bleeds down within seconds you have a check ball or regulator problem. They all reside in the fuel tank.
Your issue is very likely fuel related.
On a related note, did you recently install headers?
Also, don't relocate your IAT sensor. People who recommend this don't know how it's location effects your cars calculated DA. Relocating it tells it that the air is cooler, therefore denser, and it gives it more fuel. But this doesn't mean increased power, it can, but typically it LOOSES power by doing this. Our vehicles already run rich from the factory, making the car think the air is cooler than it's factory calibrated location makes it run even richer. It's all moot anyway I guess cause the O2's will trim it back to stoich anyway.
Last edited by hrcslam; Jul 18, 2014 at 08:29 AM.
Okay, I have had a warm engine hard start condition. When it is cold, she fires right up, after I have driven for 10-15 miles then park for 20 min and try a restart she just turns over. I will normally just turn the key to start for one sec, if she does not start I bring the ignition back to on, wait 3-5 seconds then back to start. She fires every time.
I just obtained a fuel rail pressure gauge and here are the indications with a cold engine.
1. Connected gauge, pressure 0psi
2. Turned ignition to the on position, pressure went to 20psi, then began to bleed down.
3. Turned ignition off then back on, pressure went to 40psi, then began to bleed down.
4. Turned ignition off then back on again, pressure jumped to 59psi and bled down fast.
Note, each ignition cycle was performed in five seconds intervals.
5. Turned ignition to start and she fired right up, fuel pressure was steady at 59psi at idle. I revved her several times and pressure on dropped to 58psi, then back to 59psi.
Tomorrow I will perform the hot engine diagnosis...
Thoughts from anyone so far?
Questions?
I just obtained a fuel rail pressure gauge and here are the indications with a cold engine.
1. Connected gauge, pressure 0psi
2. Turned ignition to the on position, pressure went to 20psi, then began to bleed down.
3. Turned ignition off then back on, pressure went to 40psi, then began to bleed down.
4. Turned ignition off then back on again, pressure jumped to 59psi and bled down fast.
Note, each ignition cycle was performed in five seconds intervals.
5. Turned ignition to start and she fired right up, fuel pressure was steady at 59psi at idle. I revved her several times and pressure on dropped to 58psi, then back to 59psi.
Tomorrow I will perform the hot engine diagnosis...
Thoughts from anyone so far?
Questions?
Okay, I have had a warm engine hard start condition. When it is cold, she fires right up, after I have driven for 10-15 miles then park for 20 min and try a restart she just turns over. I will normally just turn the key to start for one sec, if she does not start I bring the ignition back to on, wait 3-5 seconds then back to start. She fires every time.
I just obtained a fuel rail pressure gauge and here are the indications with a cold engine.
1. Connected gauge, pressure 0psi
2. Turned ignition to the on position, pressure went to 20psi, then began to bleed down.
3. Turned ignition off then back on, pressure went to 40psi, then began to bleed down.
4. Turned ignition off then back on again, pressure jumped to 59psi and bled down fast.
Note, each ignition cycle was performed in five seconds intervals.
5. Turned ignition to start and she fired right up, fuel pressure was steady at 59psi at idle. I revved her several times and pressure on dropped to 58psi, then back to 59psi.
Tomorrow I will perform the hot engine diagnosis...
Thoughts from anyone so far?
Questions?
I just obtained a fuel rail pressure gauge and here are the indications with a cold engine.
1. Connected gauge, pressure 0psi
2. Turned ignition to the on position, pressure went to 20psi, then began to bleed down.
3. Turned ignition off then back on, pressure went to 40psi, then began to bleed down.
4. Turned ignition off then back on again, pressure jumped to 59psi and bled down fast.
Note, each ignition cycle was performed in five seconds intervals.
5. Turned ignition to start and she fired right up, fuel pressure was steady at 59psi at idle. I revved her several times and pressure on dropped to 58psi, then back to 59psi.
Tomorrow I will perform the hot engine diagnosis...
Thoughts from anyone so far?
Questions?
Hot fuel in the rails will raise pressure there and force it
against the checkvalve's ability to hold pressure, and it
will do that until fuel has left the rails (vapor, you can get
lots of volume where cold gas would quit pushing shortly).
Then you have a void to fill, in a dead-head system that
can only be done with a lot of pedal (opening the injectors)
and time@pressure.
A check valve that leaks back a little, cold, but leaves
the line full (enough) can be a real problem hot when you
have a vapor push wanting to have a go at it.
Nonetheless, IAT relocation made a big improvement
on the Camaro's hot starting, for me. A dip in cold
water and put it back, is an easy enough way to see.
against the checkvalve's ability to hold pressure, and it
will do that until fuel has left the rails (vapor, you can get
lots of volume where cold gas would quit pushing shortly).
Then you have a void to fill, in a dead-head system that
can only be done with a lot of pedal (opening the injectors)
and time@pressure.
A check valve that leaks back a little, cold, but leaves
the line full (enough) can be a real problem hot when you
have a vapor push wanting to have a go at it.
Nonetheless, IAT relocation made a big improvement
on the Camaro's hot starting, for me. A dip in cold
water and put it back, is an easy enough way to see.
I replaced the fuel filter a few weeks ago which indicates I will either be dropping a fuel tank or cutting into the trunk to replace the tank fuel pump system. Hot fuel in the rails will raise pressure there and force it
against the checkvalve's ability to hold pressure, and it
will do that until fuel has left the rails (vapor, you can get
lots of volume where cold gas would quit pushing shortly).
Then you have a void to fill, in a dead-head system that
can only be done with a lot of pedal (opening the injectors)
and time@pressure.
A check valve that leaks back a little, cold, but leaves
the line full (enough) can be a real problem hot when you
have a vapor push wanting to have a go at it.
against the checkvalve's ability to hold pressure, and it
will do that until fuel has left the rails (vapor, you can get
lots of volume where cold gas would quit pushing shortly).
Then you have a void to fill, in a dead-head system that
can only be done with a lot of pedal (opening the injectors)
and time@pressure.
A check valve that leaks back a little, cold, but leaves
the line full (enough) can be a real problem hot when you
have a vapor push wanting to have a go at it.
what you are saying is logical and I plan to start looking for a fuel pump...More replies are always welcome!
it is happy hour! Okay, I have had a warm engine hard start condition. When it is cold, she fires right up, after I have driven for 10-15 miles then park for 20 min and try a restart she just turns over. I will normally just turn the key to start for one sec, if she does not start I bring the ignition back to on, wait 3-5 seconds then back to start. She fires every time.
I just obtained a fuel rail pressure gauge and here are the indications with a cold engine.
1. Connected gauge, pressure 0psi
2. Turned ignition to the on position, pressure went to 20psi, then began to bleed down.
3. Turned ignition off then back on, pressure went to 40psi, then began to bleed down.
4. Turned ignition off then back on again, pressure jumped to 59psi and bled down fast.
Note, each ignition cycle was performed in five seconds intervals.
5. Turned ignition to start and she fired right up, fuel pressure was steady at 59psi at idle. I revved her several times and pressure on dropped to 58psi, then back to 59psi.
Tomorrow I will perform the hot engine diagnosis...
Thoughts from anyone so far?
Questions?
I just obtained a fuel rail pressure gauge and here are the indications with a cold engine.
1. Connected gauge, pressure 0psi
2. Turned ignition to the on position, pressure went to 20psi, then began to bleed down.
3. Turned ignition off then back on, pressure went to 40psi, then began to bleed down.
4. Turned ignition off then back on again, pressure jumped to 59psi and bled down fast.
Note, each ignition cycle was performed in five seconds intervals.
5. Turned ignition to start and she fired right up, fuel pressure was steady at 59psi at idle. I revved her several times and pressure on dropped to 58psi, then back to 59psi.
Tomorrow I will perform the hot engine diagnosis...
Thoughts from anyone so far?
Questions?
this problem has existed the entire time I have owned the car…since 2014.
the problem doesn’t change.
any help would be appreciated.
Joined: Nov 2001
Posts: 34,638
Likes: 2,564
From: Schiller Park, ILL Member: #317
I finally made a video. This is a cold engine and I don’t have a start issue when it’s cold unless I wait for the pressure to bleed down. Then I have to cycle the key off then key on and start.
this problem has existed the entire time I have owned the car…since 2014.
the problem doesn’t change.
any help would be appreciated.
this problem has existed the entire time I have owned the car…since 2014.
the problem doesn’t change.
any help would be appreciated.
Are you saying that you replaced the pump back in 2014 but that never solved the issue? Or did you never end up doing that?
If the whole pump assembly/module was never replaced, then that's what I would still recommend.