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Discussion Starter #1 (Edited)
Hi, this is my first post. So first of all, I would like to thank this community for all the collaborative effort. I have owned my truck for a couple months and it is awesome to have a site like this to search for help and troubleshooting. Working on my truck has been a breeze and I have learned a lot thanks to you.

Now into the issue. Sometimes, I would need to crank my truck for like 6 seconds before it starts (other method is to turn the key, let it do its auto-cranking for like 4 secs, turn off, then back on and it will start the second time). This happens when I drive, let it sit for maybe 10-15 minutes, then try to start it again. If I try to start it again, just after turning it off, it will start normally. Also, if I let it sit for too long like overnight or while I'm at work it starts without any issue, it would crank for like 1 or 2 seconds before starting. The problem happens when it sits for some minutes to couple hours. Lets say I stop to pick some groceries (20 minutes) or have lunch (1 hour) it would have a hard time starting. The seller told me the issue was present when he owned it.

When I got the truck it had a check-engine code for EVAP leakage. When refueling, it would smell of gasoline in between the cab and the bed. It had a small crack at the top of fuel tank and the fuel pump was not properly seated. I went a step ahead and replaced the fuel pump, thinking that it was related to the hard to start issue. The new pump is properly seated and repaired the crack, also replaced the fuel filter, the code went away, but there was no difference about the start issue. I have already replaced the spark plugs. Next up is replacing the air filter and cleaning the MAF sensor. A friend suggested that it might be related to the fuel pressure regulator. But I would like to have more evidence before spending on it.

What do you guys thinks? Have any of you suffered from a similar issue? Do you have suggestions where to look at?
 

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Discussion Starter #5
Thanks for replies.

@OldTime I have my doubts about a weak coil. I inspected and cleaned them when I changed my spark plugs, they didn't show any signs of damage or issues. One of them was different from the other 4. I believe if a coil was the problem shouldn't I have other evident issues like misfires?

@Rustynuckles I haven't, actually didn't knew about until I searched it after you mention it. So what will trying the starter fluid could tell me? "If it starts without hesitation is this..." " If it didn't make a difference check this..."

@Bowmanzr7 I don't have a fuel pressure gage, but looks like I could pinpoint the issue with it. Watching a video about how to check it, it mentions that problems could be related to the fuel pump check valve (which I already replaced), the fuel pressure regulator or fuel injectors o-rings.
 

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I went back and reread your original post for more insight. The one thing I know for sure is to have combustion three things are needed.
Air.
Fuel.
Spark.
We can eliminate air , without that it wouldn't even run as you describe. You replaced the fuel filter and pump which should give it fuel to the rail , but you still have to check for pressure . You have 1 out of 5 coils that are different . Here is where I smell a rat. Looks like a prior problem with the coils existed and not fully repaired , I. E. poor quality replacement part or installation or fixed good enough to get by. In the case for a weak coil causing a misfire you would get a code but coil still operating though weak may only give the hard start issue.
 

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Had this happen to me... I had a bad inlet pipe on my fuel sending unit, and the fuel pressure would leak out while sitting.
 

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Discussion Starter #9
A fuel pressure leak seems probable, but the weird part is truck is hard to start after left sitting for 10 min or more after a drive. It would start fine cold or immediately after stopping. All the threads with similar situations have the issue when the car has been sitting for too long or overnight. In my case, if it let it sit for too long it will turn on without a problem. Could it be leaking then rise the pressure back again? Maybe an injector that leaks for some minutes, soaking the cylinder making hard to start, but then if left overnight all that fuel will leave the cylinder?

About the weak coils, I don't see what else could it cause besides misfires. Maybe heat soak is affecting the coils?
 

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Ok. We have 2 GM Trackers. And what you're describing is exactly what happens to Trackers. I had to have the camshaft sensor replaced on both of them!! Haven't had this problem with my Canyon YET!!! But I know there are a lot of problems GM didn't do recalls on!! Good Luck!! I'm willing to bet that is the problem!!!
 

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Discussion Starter #11
Thanks for your input. I'll list it in the possible issues / replace and test.
I was browsing other forums and read a post with the same problem as mine. The guy mentioned that the problem appeared when he took his injectors to the lab. After reinstalling them, the car was harder to start when it was sitting for 15 minutes. He did a lot of stuff but the final solution was replacing the o-rings on the injectors which he didn't when he initially serviced them. Probably they were old and brittle, so they didn't seal well or broke when he reinstall the injectors.
So, I'm having a lot of homework and testing to do before I start spending on parts.
 

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I get all my testing stuff from Autozone. Pay, then return / rent / free. For me, it's better than buying. They have the fuel pressure tester. I'e used it a couple times..:)
 

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Thanks for replies.

@OldTime I have my doubts about a weak coil. I inspected and cleaned them when I changed my spark plugs, they didn't show any signs of damage or issues. One of them was different from the other 4. I believe if a coil was the problem shouldn't I have other evident issues like misfires?

@Rustynuckles I haven't, actually didn't knew about until I searched it after you mention it. So what will trying the starter fluid could tell me? "If it starts without hesitation is this..." " If it didn't make a difference check this..."

@Bowmanzr7 I don't have a fuel pressure gage, but looks like I could pinpoint the issue with it. Watching a video about how to check it, it mentions that problems could be related to the fuel pump check valve (which I already replaced), the fuel pressure regulator or fuel injectors o-rings.
if you do try starter fluid.. make sure you squirt it in after you maf sensor . directly into the throttle body
 

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Gotcha!! The trackers both would stall and not start for bout 30 minutes. Drove me crazy!! I got stuck all over town waiting for it to "feel like" starting!! Major pain!! Good Luck!!
 

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Isn't there a check valve in the pressure line to keep the fuel from flowing back thru the pump to keep the fuel line full? Fuel pressure testing is a great starting point.
Luck
 

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Discussion Starter #17
Sorry for not coming back earlier, I didn't get email notifications for the replies.
Markmac & hammer mechanic: I replaced the pump assembly on my truck, expecting that check valve to be the issue. There was no difference after all. I checked the new pump by blowing into the pipe and the valve was working. Also, why is the issue only present when sitting for some minutes and not when sitting overnight?

I'm thinking that maybe one or more of my injectors are leaking. Their internal seals may not be seating properly, so when I park the truck, they drip into the manifold, flooding it with fuel. There are no problems starting the truck right after shutting it off, as the manifold may not be yet flooded. But as the minutes go by, the problem becomes more evident. Getting closer to the 15 minutes mark must be when the injectors have fully leaked the fuel pressure and the manifold is mostly flooded. Letting the truck sit for hours may allow the leaked fuel to evaporate and start almost immediately.

Another thing I noticed. I was checking the fue pressure regulator, so I started the engine and unplugged the vacuum line on top of the FPR to see if it was leaking. To my surprise, the engine just kept running as usual and there was no vacuum in that line, is that normal? I read in another thread that the FPR in the Colorado is not vacuum biased. So what is that line supposed to do or is it controlled to have vacuum under certain conditions?
 

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uhhh. Didja ever go to Autozone and get their fuel pressure tester? That'd tell ya in about 15 minutes it the injectors are leaking.
 
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