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2004 gmc envoy_slt_xl
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Discussion Starter · #1 ·
Haven't found any postings with symptoms quite like this, hoping to get some ideas on what this could be....

'04 Envoy XL 4x4, I-6 with 105K miles (original owner): If the outside air temperature is 20 degrees F or colder, the vehicle will start FINE first thing in the morning. However, after driving for a short time and then parking it for 1-3 hours in the cold, it will sometimes require a very long crank (7+ seconds) before it will start again. Doesn't seem to have any problems at all when the air temp is above 20 F. Took it to the dealer, they didn't find any codes and couldn't duplicate it so they charged me $95 and gave it back to me.

This is my wife's truck, and she's very concerned about getting stranded somewhere with our two young daughters (can't blame her). Please help, or I will be forced to part with my paid-off and otherwise AWESOME Envoy, and replace it with a new $50K Acadia that will require me getting a second job and/or selling one of my organs. Thanks!
 

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2003 chevy trailblazer_ltz
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if it is running fine I would start with fuel pressure as well. do you have a fuel pressure guage?

but it is strange it starts in the morning fine. I was going to suggest a leaking fuel pump check valve but that would rule it out (i think)
 

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2004 gmc envoy_slt_xl
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Discussion Starter · #5 ·
if it is running fine I would start with fuel pressure as well. do you have a fuel pressure guage?

but it is strange it starts in the morning fine. I was going to suggest a leakinging fuel pump check valve but that would rule it out (i think)

I don't have a fuel pressure guage, but the dealer supposedly checked out pressure and it was okay. Of course, they couldn't duplicate it when they had it so I guess that's not a surprise.

I did have another thought though - when we park it overnight it is in our garage. It's not heated or anything but it is attached, so it is probably 10-15 degrees warmer in there than the outside temperature. We haven't gotten much lower than about 10 degees around here overnight (yet), so maybe it just hasn't gotten cold enough in the garage for the issue to occur.

So I guess the question 'could' become, what is causing a hard start any time the vehicle sits for at least an hour in temps below 20 degrees?
 

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2003 chevy trailblazer_ltz
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one suggestion i have is to cylce the key on and off a couple time (wait a couple seconds in the on position) and see if it fires up after this. I had to do this when my fuel pressure was bleeding down over night (fuel pump). It just lets the pump build fuel pressure back up.

other than that the problem only when its cold is stumping me at the moment.

I'm assuming regular maintenance is done, ie fuel filter, plugs, air filter, TB cleaned etc.... not that this is directly related but its nice to rule out the basics
 

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2004 gmc envoy_slt
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I have the same issue. It's the fuel pump. It's bleeding back. Just turn the key to the 'on' position to allow the fuel pump to re-pressurize the system. Leave it there for a second or two then turn it to the start position. You don't need to do more than that for now.

You can borrow a pressure gague from a parts store. It just screws into the valve on the fuel rail.
 

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Discussion Starter · #8 · (Edited)
I have the same issue. It's the fuel pump. It's bleeding back. Just turn the key to the 'on' position to allow the fuel pump to re-pressurize the system. Leave it there for a second or two then turn it to the start position. You don't need to do more than that for now.

You can borrow a pressure gague from a parts store. It just screws into the valve on the fuel rail.
So does your issue also only occur during cold temps too? How do you know it is the fuel pump? I assumed that if it was the pump "bleeding back," it would happen all the time. If I did borrow the fuel pressure gauge, how should I go about testing the system? To answer Garrett, I've replaced the air and fuel filter recently, but I have never touched the plugs or throttle body.
 

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I would still put my money on the fuel pump, but again, try the cycle key a couple times and see if it stops. That will narrow it down for you. I drove mine like that for close to 6 months and just replaced it because it annoyed me, not because it failed. It's not a fun job either.

Just a guess but cold temps could be increasing clearances around the seals in the fuel pump. I cannot remember if the problem got worse or not for me in the winter.
 

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2002 gmc envoy_slt
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You guys may be thinking through way too far. He starts fine stone cold, so the fuel pump is most likely fine. Most likely in 1-3 hours, there's one of two things going on. Either the sensors believe the motor is ice cold, its 20 or below and it really isn't....that amount of time isn't enough for the internal engine components to get that cold. It cranks, squirts enough fuel for a dead cold motor, floods the intake and now requires a few seconds of cranking air to balance out the fuel that was dumped in. This problem can also be a result of a dirty/leaking injector, where you park and the injectors drizzle/drip fuel into the intake. Its cold and doesn't evaporate and puddles a bit, you go to start and are temporarily flooded. For a test, have her lightly press the accelerator when she goes to crank it after sitting briefly in those temps. If it starts 1st try, this is the issue and I'd clean the injectors before doing any other diagnostics.

If cleaning doesn't fix them, you really need a scan-tools to see what the perceived temps are and what's going one with those cranks. If I were a betting man, I'd wager the problem is the fuel mixture when cranking under those circumstances, you just need to narrow down the cause. Dirty/Leaky injectors would be my first bet, followed by the sensors. - That issue is fairly common with a wide arrange of vehicles by the way, its just not as much a problem with fuel injection than it was with a carb.
 

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You guys may be thinking through way too far. He starts fine stone cold, so the fuel pump is most likely fine. Most likely in 1-3 hours, there's one of two things going on. Either the sensors believe the motor is ice cold, its 20 or below and it really isn't....that amount of time isn't enough for the internal engine components to get that cold. It cranks, squirts enough fuel for a dead cold motor, floods the intake and now requires a few seconds of cranking air to balance out the fuel that was dumped in. This problem can also be a result of a dirty/leaking injector, where you park and the injectors drizzle/drip fuel into the intake. Its cold and doesn't evaporate and puddles a bit, you go to start and are temporarily flooded. For a test, have her lightly press the accelerator when she goes to crank it after sitting briefly in those temps. If it starts 1st try, this is the issue and I'd clean the injectors before doing any other diagnostics.

If cleaning doesn't fix them, you really need a scan-tools to see what the perceived temps are and what's going one with those cranks. If I were a betting man, I'd wager the problem is the fuel mixture when cranking under those circumstances, you just need to narrow down the cause. Dirty/Leaky injectors would be my first bet, followed by the sensors. - That issue is fairly common with a wide arrange of vehicles by the way, its just not as much a problem with fuel injection than it was with a carb.
I am having the same issues. what sensors should be checked after cleaning the injectors and throttle body etc.?
 
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