Hard start when hot - Page 3 - 3000GT/Stealth International Message Center

daddy · 08-13-2007, 06:45 PM

^ Yes. I had same problem. Ran some random injector cleaner crap and it helped. Still getting a bit low idle on hot restart (400-500rpm) but much better than it was before.

mako · 08-13-2007, 06:50 PM

Bingo….
Plus a cold car wants more fuel so this goes un-noticed. A hot car has the fuel pump holding allot of pressure causing injector to leak if dirt is holding them slightly open. If this sounds like your symptoms, it may just be the problem.
I always use injector cleaner in all my cars even without the above symptoms just to keep everything clean.
Again, I like Techron. You can get it at autozone. Run a few tanks with it in.
Mako
PS, you can always have your injectors professionally cleaned if they are really dirty.

braddman · 08-16-2007, 07:16 PM

I'll try the injector cleaner, thanks guys!

daddy · 08-16-2007, 09:03 PM

Just so you know it might take a bit before you see the result. It took me about 2 months.

RIP50AK · 08-21-2007, 07:33 PM

I had a very similar problem, started fine when cold, hard or very hard to start when warm, and sometimes idle would be way off. It turned out to be the water temperature sensor was wacky giving the ECU bad info. Once it was replaced everything worked normally.

smashbar · 06-09-2008, 05:21 AM

Anyone ever get to the bottom of this???

daddy · 06-09-2008, 04:27 PM

Injectors. I replaced mine to 550's and no problems at all restarting right now.

AK Twin Turbo · 06-09-2008, 05:01 PM

replace fuel filter...that'll do it. just fixed that same problem this past weekend...took me 30 mins.

DoctorDex · 06-09-2008, 06:32 PM

I replaced my filter with an aftermarket aeromotive unit and it didn't help at all.

mugs · 06-09-2008, 06:45 PM

DoctorDex did you ever try this?? The removal not replacement.

Stealth 316 - Fuel Pressure Regulator Upgrade

Stealth316.com by:Jeff Lucius

"The fuel pressure control solenoid (or valve) is used by the engine control unit (ECU) only to increase fuel pressure during hot engine starts when there is a greater possibility of fuel vapor being generated in the fuel lines. When the air intake temperature exceeds 140ºF (60ºC) and the engine coolant temperature exceeds 194ºF (90ºC), the ECU uses the fuel pressure control solenoid (for up to two minutes) to allow outside air into the vacuum hoses to increase fuel pressure. In addition, the ECU increases fuel injector activation duration (richens the mixture). These two actions by the ECU are what I believe is a cause of the hot-engine hard-start condition I and many others have experienced on a hot summer day after turning the engine off for a short while. The engine acts like it is flooded for maybe a minute then runs fine. Because this is the only purpose of the fuel pressure control solenoid, I decided to remove it. I don't think there is much we can do about this part of the ECU programming short of going to stand-alone engine management. Owners that have removed the fuel pressure control solenoid, whether upgrading to an aftermarket FPR or not, have not reported problems related to this. I will update this web page if I encounter problems."

Did you ever try this?? I have the same sort of problem. I have been waiting to try it, but my car has been at the shop for the last 7 weeks.

08-13-2007, 06:50 PM	#22 (permalink)
mako Parting out = Extinction. Join Date: Jun 2007 Trader Rating: (4)	Re: Hard start when hot Bingo…. Plus a cold car wants more fuel so this goes un-noticed. A hot car has the fuel pump holding allot of pressure causing injector to leak if dirt is holding them slightly open. If this sounds like your symptoms, it may just be the problem. I always use injector cleaner in all my cars even without the above symptoms just to keep everything clean. Again, I like Techron. You can get it at autozone. Run a few tanks with it in. Mako PS, you can always have your injectors professionally cleaned if they are really dirty. __________________ 1969 Corvette Roadster 1966 Mustang Convertible 1997 3000GT Coming soon, 1996 Viper-GTS View Pictures @ http://www.drivehq.com/folder/p2483017.aspx (Use the Slideshow feature) Last edited by mako : 08-13-2007 at 07:01 PM.

08-16-2007, 07:16 PM	#23 (permalink)
braddman New User - Please be kind Join Date: Dec 2006 Location: North Hollywood, CA Drives: 2002 CLK55 AMG Trader Rating: (0)	Re: Hard start when hot I'll try the injector cleaner, thanks guys!

08-16-2007, 09:03 PM	#24 (permalink)
daddy ๏̯๏ Join Date: May 2006 Location: Bronx Drives: BPU 92TT Trader Rating: (25)	Re: Hard start when hot Just so you know it might take a bit before you see the result. It took me about 2 months.

08-21-2007, 07:33 PM	#25 (permalink)
RIP50AK Forum Member Join Date: May 2003 Trader Rating: (1)	Re: Hard start when hot I had a very similar problem, started fine when cold, hard or very hard to start when warm, and sometimes idle would be way off. It turned out to be the water temperature sensor was wacky giving the ECU bad info. Once it was replaced everything worked normally.

06-09-2008, 05:21 AM	#26 (permalink)
smashbar Forum Member Join Date: Nov 2005 Trader Rating: (4)	Re: Hard start when hot Anyone ever get to the bottom of this???

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06-09-2008, 04:27 PM	#27 (permalink)
daddy ๏̯๏ Join Date: May 2006 Location: Bronx Drives: BPU 92TT Trader Rating: (25)	Re: Hard start when hot Injectors. I replaced mine to 550's and no problems at all restarting right now.

06-09-2008, 05:01 PM	#28 (permalink)
AK Twin Turbo soo....cold.... Join Date: Sep 2006 Location: Elmendorf AFB, AK Drives: 69th Stealth Trader Rating: (4)	Re: Hard start when hot replace fuel filter...that'll do it. just fixed that same problem this past weekend...took me 30 mins. __________________ Free Boost \| Greddy Type-S \| Cold Air Intake \| MBC @ 12psi \| MSD 8mm Heli-Core Wires '99 Lifters \| Autometer Gauges: Boost, Water Temp, Oil Press

06-09-2008, 06:32 PM	#29 (permalink)
DoctorDex Forum Member Join Date: Jul 2005 Location: Edmonton, AB Drives: '91 VR4 - RIP Trader Rating: (13)	Re: Hard start when hot I replaced my filter with an aftermarket aeromotive unit and it didn't help at all. __________________ '91 VR4 - Modlist: DR650R turbos, Snow stage 2D alky kit, DSM SMICs, blowthrough ported LT1 MAS, Dejon Tool intakes & y-pipe, Blitz DSBC Spec R, HKS SSQV BOV, PTE 580cc injectors, Dual feed fuel system with Aeromotive FPR & filter, Hotwired Supra pump, HKS DLI, MSD Wires, Apex'i S-AFC II, MAFTranslator, Turbobob ECU, Scanmaster III, LC-1 WBO2, ESP downpipe, Vac/EGR delete, Gutted precats and test pipe, Maximal solid mounts, 300m 18 spline output shaft, Centerforce Dual Friction clutch, RPS flywheel, GC coilover conversions with helper springs, Powerslot slotted rotors, Goodridge SS brake lines, Hawk pads (front), Stillen metal matrix pads (rear)

06-09-2008, 06:45 PM	#30 (permalink)
mugs Forum Member Join Date: May 2002 Location: Canada Trader Rating: (0)	Re: Hard start when hot DoctorDex did you ever try this?? The removal not replacement. Stealth 316 - Fuel Pressure Regulator Upgrade Stealth316.com by:Jeff Lucius "The fuel pressure control solenoid (or valve) is used by the engine control unit (ECU) only to increase fuel pressure during hot engine starts when there is a greater possibility of fuel vapor being generated in the fuel lines. When the air intake temperature exceeds 140ºF (60ºC) and the engine coolant temperature exceeds 194ºF (90ºC), the ECU uses the fuel pressure control solenoid (for up to two minutes) to allow outside air into the vacuum hoses to increase fuel pressure. In addition, the ECU increases fuel injector activation duration (richens the mixture). These two actions by the ECU are what I believe is a cause of the hot-engine hard-start condition I and many others have experienced on a hot summer day after turning the engine off for a short while. The engine acts like it is flooded for maybe a minute then runs fine. Because this is the only purpose of the fuel pressure control solenoid, I decided to remove it. I don't think there is much we can do about this part of the ECU programming short of going to stand-alone engine management. Owners that have removed the fuel pressure control solenoid, whether upgrading to an aftermarket FPR or not, have not reported problems related to this. I will update this web page if I encounter problems." Did you ever try this?? I have the same sort of problem. I have been waiting to try it, but my car has been at the shop for the last 7 weeks. __________________ Some people are alive simply because it's illegal to kill them!! If I help you out, please help make the community better and pay it forward. Last edited by mugs : 06-09-2008 at 07:40 PM. Reason: for clarification