[Justin23]

Alright guys so about 5 days ago i noticed that my truck took alittle longer than usual. Each start after that got worse and worse til it just wouldnt start 5 starts later. After i got it jumped assumed it was the battery but the next day it seemed to be fine. Every once in awhile now it has a very rough start and I swear i feel a power loss from time to time. But then other times it fires right up and has great power. Im now thinking a ground issue could be the problem or possibly its simply the battery playing tricks. what do you guys think??


2005 Colorado 3.5L

 

[08Canyon]

If you suspect the battery, take it to a parts store and ask them to LOAD test it.

Battery should not cause it to start rough though.

Could be a dirty Throttle Body
Dirty Mass Air Flow Sensor
Low Fuel pressure

I don't know what led you to believe the battery was bad. Unless you are trying to describe that the truck turns over slowly, which doesn't necessarilly mean a rough start. Not to me it doesn't. My definition of rough start is it tries to start, does start then stalls out. Or once it starts it seems as if it's misfiring (erratic idle).

If it simply cranks slowly, then I'd lean towards a battery. Is the battery an original 2005 battery?

 

[Justin23]

I was suspecting the battery because it is slow to start and rattles abnormally as soon as it fires. Just doesnt seem like a clean start. But then other days it is fine. Battery is only about 2 years old. im going to go get a load test tomorrow and see what they say. I cleaned the throttle body up when i changed the spark plugs but ill change the fuel filter and clean up the MAF sensor.

Sorry for the confusion!

 

[08Canyon]

Interesting.

You mean slow crank? Not slow start? I mean, isn't a start a start? Or do you mean it cranks a lot before it actually starts?

That seems more like a fuel supply. Like perhaps the fuel pressure is bleeding off after it has sat for an extended period of time then it takes a couple seconds for the pressure to build up before the coil can light it up.

If it's erratic once it gets running, I think (in theory) it may be stumbling around until fuel pressure is normalized.

Any codes?
Any work done to the truck recently?

You could try disconnecting the battery for an hour. That resets the BCM, and just maybe that will smooth things out. Not likely but worth a try I suppose.

 

[Justin23]

Okay so I had the battery checked out. Everything is fine. Cleaned the maf sensor and changed out the fuel filter and spark plugs. Filter was terrible. It seems to be a lot better but now it only does it after sitting for a while. Like first crank of the day after sitting all night. Still kinda stumbles around upon firing and takes about 5 seconds longer than usual to ignite. Your definitely right about being a fuel issue and definitely makes sense that the fuel pressure could be dropping off over time. What could be causing this? :ugh:

 

[darvoh]

I would be interested in hearing any replies on this, trucks been doing the same thing for about a month now. Drives perfect, and starts up immediately when Hot. But that first startup after sitting a couple hours is a stutter lol changing to Denso iridium spark plugs and a new fuel filter this weekend.


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[Justin23]

Yeah it's very strange. When it's warm fires up like a brand new truck but when it's cold and been sitting like you said it shutters and stumbles around before firing. Lol. I'm stumped!:ugh:

 

[08Canyon]

I would be interested in hearing any replies on this, trucks been doing the same thing for about a month now. Drives perfect, and starts up immediately when Hot. But that first startup after sitting a couple hours is a stutter lol changing to Denso iridium spark plugs and a new fuel filter this weekend.


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Make sure you DO NOT gap those plugs. Remove from box, install in engine. Done.

 

[08Canyon]

Okay so I had the battery checked out. Everything is fine. Cleaned the maf sensor and changed out the fuel filter and spark plugs. Filter was terrible. It seems to be a lot better but now it only does it after sitting for a while. Like first crank of the day after sitting all night. Still kinda stumbles around upon firing and takes about 5 seconds longer than usual to ignite. Your definitely right about being a fuel issue and definitely makes sense that the fuel pressure could be dropping off over time. What could be causing this? :ugh:

Some of our vehicles have a fuel pressure regulator. Or....they changed the regulator design. I don't remember exactly.

The only way to make that determination is to connect a fuel pressure gauge. If you can't do that, you may need to drop it at a shop and let them have it for several hours.

Not saying this is your situation, but I had a bad injector before. Filter media in the injector tore and became lodged in the injector valve causing the injector not to close. The outcome, instant fuel pressure loss. I connected a gauge and watched the pressure fall to zero. I'd turn the key on and it pressurized. Then instantly after the pump shut off (initial at "Key On") the pressure dropped as fuel was draining into the cylinder.

Also, I had a regulator go bad. It was erratic, pressured jumped to 80 then neglected to fall back, until it felt like it.

Neither example was on this truck. But those are things that CAN happen. Again, you'll need to have the systems pressure checked out.

I don't know if there are sensors on our trucks that cause this symptom. Some vehicles will react the way you describe when the engine is hot (or thinks it is hot). I do not believe that is true on our trucks though.

Good luck.

 

[darvoh]

Gonna due the basic tune with spark plugs, fuel filter, and if that doesn't do it ill take her in and get the fuel injectors cleaned good. No loss in power while driving just that start up, idles better after I cleaned the TB and MAF. Prolly gonna take the TB off and clean behind the flap this time lol God knows whats back there :bricks:

 

[08Canyon]

Skip the plugs for now (unless you're bored). A bad set of plugs won't make it start any differently when cold vs. normal operating temperature.

The cost to clean injectors is pretty expensive, and likely the LAST thing on your list.

If you haven't removed the TB in the past to clean, then definitely start there. You really can't clean it adequately while mounted to the vehicle.

You haven't mentioned the year of the vehicle, or the miles on the plugs.

 

[Justin23]

Okay so here we go again. I changed the plugs and fuel filter cleaned the maf and throttle body and checked the battery. It didn't do that weird start for a while. Till this morning. It cranked for about 6 seconds before firing. Then I went to get gas and went to start it and it turned over 3 times and stopped like the battery was dead. I turned the key off and tried it again and it barely started. I have no idea what's causing this if my battery is good and cleaned the sensors and new plugs!!! :ugh:

 

[Justin23]

Darvoh have you had any luck with the problem?

 

[darvoh]

Justin I replaced the spark plugs and fuel filter this past weekend. Truck starts up a lil quicker on cold starts now and a better response on the throttle, not an immediate start up like you'd want but that might be the nature of our trucks. Mpg seems a lil better as well. Truck has 103k miles on it.


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[scottrwilliams]

My truck has been doing this a lot lately as well. But only when it's hot outside. I live in AZ so it's been over 100 lately. But when I get up at 5 AM and it's 80 outside, it starts instantly.

I'm going to clean the TB and replace the fuel filter as well. It's got 100,000 miles now and all I've ever done is change the oil and replace the spark plugs once and clean the MAF. I wonder if I need TB cleaner or if I can use the MAF cleaner. My idle is low lately too. And for some reason if I brake hard it will go down to 500 RPM and seems close to stalling.

It's throwing a P0300 and a P0128

Also, when it's being a bitch, the passlock light will stay on sometimes.

Have you guys seen this? http://www.355nation.net/forum/service-bulletins/24680-technical-service-bulletins-fuel-system-driveability-issues-mil-multiple-dtcs.html

Hopefully I wont have to pay for that procedure

Also, it's not my battery cause she'll crank and crank and crank all day. Usually it starts and immediately dies. I repeat that till it stays running. And once it's running if I stop somewhere and run in really quick, it will start again easily.

I think the strangest thing is it only happens when it's really hot outside. It's been like that for a while buy it's worse lately.

 

[08Canyon]

My truck has been doing this a lot lately as well. But only when it's hot outside. I live in AZ so it's been over 100 lately. But when I get up at 5 AM and it's 80 outside, it starts instantly.

I'm going to clean the TB and replace the fuel filter as well. It's got 100,000 miles now and all I've ever done is change the oil and replace the spark plugs once and clean the MAF. I wonder if I need TB cleaner or if I can use the MAF cleaner. My idle is low lately too. And for some reason if I brake hard it will go down to 500 RPM and seems close to stalling.

It's throwing a P0300 and a P0128

Also, when it's being a bitch, the passlock light will stay on sometimes.

Have you guys seen this? http://www.355nation.net/forum/service-bulletins/24680-technical-service-bulletins-fuel-system-driveability-issues-mil-multiple-dtcs.html

Hopefully I wont have to pay for that procedure

Also, it's not my battery cause she'll crank and crank and crank all day. Usually it starts and immediately dies. I repeat that till it stays running. And once it's running if I stop somewhere and run in really quick, it will start again easily.

I think the strangest thing is it only happens when it's really hot outside. It's been like that for a while buy it's worse lately.

Yes, use the correct cleansers - Throttle Body Cleaner for the Throttle Body.

 

[08Canyon]

Okay so here we go again. I changed the plugs and fuel filter cleaned the maf and throttle body and checked the battery. It didn't do that weird start for a while. Till this morning. It cranked for about 6 seconds before firing. Then I went to get gas and went to start it and it turned over 3 times and stopped like the battery was dead. I turned the key off and tried it again and it barely started. I have no idea what's causing this if my battery is good and cleaned the sensors and new plugs!!! :ugh:

I have to ask...what does

"and checked the battery" mean?

Have you located and cleaned the ground connection locations? I don't recall i that was discussed in this thread.

What plugs did you use? Just curious - I do not believe that has anything to do with your starting issue (nor did I ever think it did).

 

[Joe canyon]

Map or iat / tps problem?

 

[Justin23]

I cleaned the map but not the tps. Checked the batterer meaning had it it tested to be sure it was holding a change. It basically acts like the battery is dead when it's not. It's even to the point where when the truck finally fires up after about 6 seconds of struggle the lights are dim for about 2 seconds and then brighten up. I have not checked the grounds. Do you have a thread that would show me the locations?

 

[Merica!]

One ground is right behind the battery. And I think there is one on the passenger side somewhere.