Rough start in the cold
11-30-2007, 07:34 PM
#1
Rough start in the cold First off, this is a 3800 V6, not an LS1, I know many things are similar as far as ignition and fuel system goes though. I'm running on brand new plugs and wires and have seafoamed right before I changed them so all that is taken care of.
Now that the weather is getting colder I'm finding out how my car behaves in it. Apparently it isn't too happy starting up in the cold.
Now I either have a weepy injector or a seeping fuel pressure regulator (or something) because I noticed that after the car sits for awhile I have to turn the key to run, let the fuel pump run until it stops, turn key off and repeat, then start. Otherwise it just cranks and cranks and cranks then sputters and finally is fine. Not sure which it is but once it starts I'm good to go.
Anyway, in the cold I start it up and even after doing the prime, off, prime thing it still starts rather hard and rough. Let it warm up a couple minutes and it is good to go. So just startup is a little of a pain.
Anything I can do to clear this up so it starts easier? Or is it just the nature of the beast? I suppose tracking down the reason for no fuel pressure at the engine after sitting for awhile would help but I don't know where to start on that.
Now that the weather is getting colder I'm finding out how my car behaves in it. Apparently it isn't too happy starting up in the cold.
Now I either have a weepy injector or a seeping fuel pressure regulator (or something) because I noticed that after the car sits for awhile I have to turn the key to run, let the fuel pump run until it stops, turn key off and repeat, then start. Otherwise it just cranks and cranks and cranks then sputters and finally is fine. Not sure which it is but once it starts I'm good to go.
Anyway, in the cold I start it up and even after doing the prime, off, prime thing it still starts rather hard and rough. Let it warm up a couple minutes and it is good to go. So just startup is a little of a pain.
Anything I can do to clear this up so it starts easier? Or is it just the nature of the beast? I suppose tracking down the reason for no fuel pressure at the engine after sitting for awhile would help but I don't know where to start on that.
11-30-2007, 08:03 PM
#3
Oh really? Why? Car runs absolutely normal after startup... or is the pump the reason the fuel pressure falls off? Well if it is the pump I'm taking the back door approach to replacing it from the hatch, I'm not dropping that tank if I can avoid it.
Oh yeah something I forgot to mention, ever since I seafoamed when I first turn the key to run and the fuel pump kicks on there is this lower-toned "whiiiiiisshhh-tik" noise from the engine compartment, on the passenger side near the back half. Sounds kinda like rolling a medium-sized ball bearing down a tube. Any ideas what that could be? When I was fighting with the brake booster line I was pushing the fuel lines around some but it wasn't like I bent them over or anything, just flexed the rubber part a little. When the engine is warm and I go to start it that noise isn't there.
Oh yeah something I forgot to mention, ever since I seafoamed when I first turn the key to run and the fuel pump kicks on there is this lower-toned "whiiiiiisshhh-tik" noise from the engine compartment, on the passenger side near the back half. Sounds kinda like rolling a medium-sized ball bearing down a tube. Any ideas what that could be? When I was fighting with the brake booster line I was pushing the fuel lines around some but it wasn't like I bent them over or anything, just flexed the rubber part a little. When the engine is warm and I go to start it that noise isn't there.
11-30-2007, 08:12 PM
#4
TECH Fanatic
I think it could still be a fuel pump issue. Reason being when the car is warm there is still plenty of fuel pressure/fuel in the lines. When the car is cold have someone key it up and hit the schraeder valve and see if you have adequate fuel pressure at the rail. Hope that helps.
11-30-2007, 08:18 PM
#5
Ouch, looking at around $300. I don't have that kind of money right now 
if it is the pump, hopefully it'll behave itself for awhile until I can afford it (like, until summer....)
I'll check the fuel pressure at the valve, I'm pretty sure I do have a loss of pressure after it sits (not sure what else it would be that would make it crank for awhile after sitting) but maybe it is just something else like a fitting isn't tight or something and that is what I'm hearing.... *wishful thinking*
if it is the pump, hopefully it'll behave itself for awhile until I can afford it (like, until summer....)I'll check the fuel pressure at the valve, I'm pretty sure I do have a loss of pressure after it sits (not sure what else it would be that would make it crank for awhile after sitting) but maybe it is just something else like a fitting isn't tight or something and that is what I'm hearing.... *wishful thinking*
12-01-2007, 09:49 AM
#7
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sure sounds like the pump... the pump has a 1 way check valve in it that holds the fuel pressure in the lines and keeps fuel in the lines after the car is shut off. If that 1 way check valve goes bad the fuel system will loose pressure as soon as you shut it off and all the fuel will drain back into the tank. So the next morning when you go to start it you are basically re-priming the entire fuel system by cranking the car until the fuel finally reaches the fuel rail. Eventually the pump itself will burn out because its being run for several seconds on every cold start with no fuel it.
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12-01-2007, 11:05 AM
#8
Sorry for being a noob but what type of gauge? I don't have a garage full of tools and a brain full of car know-how like many here (I'm a computer and electronics guy who is learning about cars and such). Do I check the pressure at the schraeder valve?
12-01-2007, 11:37 AM
#9
TECH Senior Member
Fuel pressure gauge, and you're correct, check it at the fuel rail. I'd connect it and see what it is after cycling the key a few times to get the highest reading - then turn the key off leaving it connected to see if you're losing pressure over time. They're not expensive. Not sure how much drop if any is acceptable - I'll look in my Helms.
12-01-2007, 12:10 PM
#11
TECH Senior Member
For the 3.8 my helms says "The fuel pressure may vary slightly if the fuel pump stops running. After the fuel pump stops running, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gauge for 1 minute." Then goes on with further diagnostics...
12-02-2007, 12:32 PM
#12
OK here is a quick video of what it does. Turn your sound up a little, I don't have performance exhaust on this V6 so it is harder to hear 
Now this wasn't as bad as it has been, this is moderate. Usually it is worse than that.
Where can I pick up a fuel pressure gauge to test my pressure with?
Now this wasn't as bad as it has been, this is moderate. Usually it is worse than that.
Where can I pick up a fuel pressure gauge to test my pressure with?
Last edited by SparkyJJO; 12-02-2007 at 10:34 PM.
