compyelc4
Well-known member
- Joined
- May 1, 2002
- Messages
- 609
- Location
- Dayton, Ohio
- Corvette
- '95 LT1 Coupe, Comp Yell; C6 Roadster, Vel Yell
Can someone please explain to me how I can have zero fuel pressure on a cold start and get an instant startup? This is not the whole story so please allow me to explain, and sorry for the long post.
I localized my "long crank til startup" (LCTS) problem to warm days only. I have 12,000 miles on my '07, but I've had this problem since just after the warranty expired. For a while I thought Techron cleared up the problem, but this summer the problem returned with a vengeance. When the weather is below 60-70 degrees F, whether on a cold or hot engine, she fires right up, time and time again. Above 60-70 degrees I get a mostly an intermittent delayed 3-4 second startup (I know, this sounds like a short time interval, but believe me it seems like an eternity, and it is embarrassing). I have found if I keep the accessory side of the start button depressed for about 6 seconds I can hear the the fuel pump run for a second or two, and then WHETHER HOT OR COLD OUT I get an instant startup.
Now listen to this!!!!........I checked the fuel pressure at the rail yesterday. It was about 50 degrees F out. The C6 had been sitting all night. The static fuel pressure was 0 pounds! I hit the ignition and within 1/2 second the fuel pressure shot up to a steady 62 pounds and I had an instant startup. I cut the ignition and watched the full pressure immediately start dropping. It took about 3 minutes to reach 0 pounds!!! I tried another startup and again the fuel pressure instantly shot up to 62 pounds and I got another instant startup. I let it sit all night. Today, when I got home from work I did the identical procedure, experiencing an immediate startup with an initial 0 pounds of pressure. PLEASE EXPLAIN HOW THIS CAN BE?! I have heard on several forums that low fuel pressure at startup is indicative of a fuel leak and will cause a long crank til startup. My LS2 just laughed at this theory. What are the physics involved when the ambient temperature is above 60-70 degrees F, I have 0 pounds of pressure at startup and I get a long crank rather than an immediate startup, then under the same conditions below 60-70 degrees F ambient I get an immediate startup?
BTW, I have no soft or hard codes set. A Tech 2 shows everything is within operating limits. Even on a long crank startup there is no black exhaust, no stumbling idle or acceleration. Once she fires she runs like she should.
I believe that losing fuel pressure that fast to one or more leaky injectors would result in one smokey, stumbling engine after she starts (and I don't have that), so I think I may have a drainback problem in the tank but why in the heck does this pressure leakdown to zero pounds in the rails not result in a long crank til startup irregarless of ambient temperature?
PS- She's all stock, no mods, babied and drinks only top-tier fuel only.
You may have read something similar from me in another forum, but I cleaned it up a bit and posted it here, to my home forum.
I localized my "long crank til startup" (LCTS) problem to warm days only. I have 12,000 miles on my '07, but I've had this problem since just after the warranty expired. For a while I thought Techron cleared up the problem, but this summer the problem returned with a vengeance. When the weather is below 60-70 degrees F, whether on a cold or hot engine, she fires right up, time and time again. Above 60-70 degrees I get a mostly an intermittent delayed 3-4 second startup (I know, this sounds like a short time interval, but believe me it seems like an eternity, and it is embarrassing). I have found if I keep the accessory side of the start button depressed for about 6 seconds I can hear the the fuel pump run for a second or two, and then WHETHER HOT OR COLD OUT I get an instant startup.
Now listen to this!!!!........I checked the fuel pressure at the rail yesterday. It was about 50 degrees F out. The C6 had been sitting all night. The static fuel pressure was 0 pounds! I hit the ignition and within 1/2 second the fuel pressure shot up to a steady 62 pounds and I had an instant startup. I cut the ignition and watched the full pressure immediately start dropping. It took about 3 minutes to reach 0 pounds!!! I tried another startup and again the fuel pressure instantly shot up to 62 pounds and I got another instant startup. I let it sit all night. Today, when I got home from work I did the identical procedure, experiencing an immediate startup with an initial 0 pounds of pressure. PLEASE EXPLAIN HOW THIS CAN BE?! I have heard on several forums that low fuel pressure at startup is indicative of a fuel leak and will cause a long crank til startup. My LS2 just laughed at this theory. What are the physics involved when the ambient temperature is above 60-70 degrees F, I have 0 pounds of pressure at startup and I get a long crank rather than an immediate startup, then under the same conditions below 60-70 degrees F ambient I get an immediate startup?
BTW, I have no soft or hard codes set. A Tech 2 shows everything is within operating limits. Even on a long crank startup there is no black exhaust, no stumbling idle or acceleration. Once she fires she runs like she should.
I believe that losing fuel pressure that fast to one or more leaky injectors would result in one smokey, stumbling engine after she starts (and I don't have that), so I think I may have a drainback problem in the tank but why in the heck does this pressure leakdown to zero pounds in the rails not result in a long crank til startup irregarless of ambient temperature?
You may have read something similar from me in another forum, but I cleaned it up a bit and posted it here, to my home forum.