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Hard start when cold

knightgang
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knightgang Enthusiast

knightgang

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2001 1500 HD, 6.0 Vortec with 225K. This truck has gotten hard to start when it is cold. Takes about 2-3 crank attempts of 2-3 seconds to crank. I have tried an extended crank of 5-8 seconds and it still will not start on the first attempt. Most of the time when it is warm it starts first time everytime. This just started a few weeks ago and nothing on the vehicle has changed.

 

I am currently on vacation and do not have my scanner with me, however the scanner at oreilly's did not pull any codes. I am concerned that it could be a fuel pump. I just hanged the fuel filter last week thinking that it could be restricting fuel flow and causing the problem. It made no change at all. Once the engine is started, everything seems normal, no loss in power, no skipping, no rough running, nothing.

 

That said, is there any suggestions on what the issue could be other than a weak fuel pump or ideas that I can start to look at before I get the truck back home. Any help is appreciated.

 

Thanks

Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted (edited)

Yup sounds like the fuel pump is on its way out. When the motor is cold due to sitting the fuel pump has lost all pressure and takes a few more longer cranks to build pressure once pressure is there it starts now when the motor is warm there is still some pressure in there due to the motor just being ran as it doesn't take as much pressure to start the motor is the reason it starts when warm.

 

Fuel pressure should be at 55-62 psi while the pump is running

 

Do your self a favor and don't skimp on a cheap pump cause with those you will be back in there in no time soon.

Edited by Silverado4x4
txab Senior Enthusiast

txab

Posted
Posted (edited)

When starting cold, try turning key on, let the pump prime, then key off. Then key on,start. See if it helps while you're on your trip. But, it's probably pump time

Edited by txab
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knightgang Enthusiast

knightgang

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I may go by a local shop here on the island and see if by chance I can borrow their fuel pressure test gauge for 10 minutes to verify. I know that fuel pumps usually just die. I do not want it to die while I am out of town or on my way back home.

 

Does anyone on this forum happen to like on Amelia Island Florida?

Colossus Senior Enthusiast

Colossus

Posted
Posted

Fuel pumps don't always just die. The symptoms you are explaining leads me to believe 1 of 2 things. The fuel sending unit, and/or the fuel pressure regulator.

knightgang Enthusiast

knightgang

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Colossus, please explain... I know the sending unit is sketchy as is has been reading inaccurately for quite some time, like maybe a year. It will read correct and then fall to nothing, many times like a ping pong ball, back and forth....

 

How would I diagnose between the regulator and the pump itself?

white1500 Senior Enthusiast

white1500

Posted
Posted

I just put in a new battery and it seems to have removed my cold start issues. I've been needing to double crank when the engine is cold: overnight, all day at work, etc. But as of Saturday she fires up right away.

 

I doubt it'll remove my cold temp issues related to the intake manifold gasket but its one less thing to worry about.

Blue2500CC Enthusiast

Blue2500CC

Posted
Posted

Fuel pumps don't always just die. The symptoms you are explaining leads me to believe 1 of 2 things. The fuel sending unit, and/or the fuel pressure regulator.

 

+1. Regulator was my first thought due to being cheaper. Had a 2k that did the same thing. Warm(er) starts, just fine. If it sat for a while (maybe 2-3+ hrs), crank a few, crank some more a few, crank a bit more, and would start.

 

Good luck!

Colossus Senior Enthusiast

Colossus

Posted
Posted

What I mean by the sending unit is the whole module in the fuel tank. The sending unit (aka the pump) the float (fuel level) and filter (if it does not have an external fuel filter, it is in the tank) Replace the whole thing which would be all those things. In the GMT-800s, they were known to go out between 60,000-100,000 miles, and the ones they were replaced with would last just about as long. However, when the pump goes out, it won't always just suddenly go bad. Sometimes it does, but most of the time it will give you a hard starting symptom like you were describing. I had an old 99 GMT-800 that more or less did what yours is doing. I would have to turn it to the on position for a few seconds to prime the pump, then turn it off, then back to on position a few seconds, then off, then on again, then turn to start, and it would start. But even that only worked for awhile before it got worse and I had to have it replaced. The FPR (fuel pressure regulator) were also very prone to leaking and failures on the GMT-800s too.

knightgang Enthusiast

knightgang

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I follow you now. I know it is an entire assembly as I have replaced several and once already on this truck. You just threw me when you mentioned sending unit...

 

Because there is no lack of power and no issue at all once it is running, I think the actual problem may be the regulator. However, due to the fact that the float sensor is erratic and not working most of the time, I will likely replace both...

 

I just wish I could replace the regulator before heading home, I do not want to get stranded.

  • Like 1
white1500 Senior Enthusiast

white1500

Posted
Posted (edited)

If your 6.0 is like my 5.3, the FPR will be on the drivers side fuel rail on top of the valve covers. It could easily be a 1 minute job and all you need are your hands.

Edited by white1500
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knightgang Enthusiast

knightgang

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thanks white. I was looking at it today and thinking that at wort I would need a flat-head screwdriver to pry off the keeper. But looking at the kit that it comes with the keeper and a C-spring clip, I was afraid that I might need need-nose pliers of even retaining ring pliers. I have all the tools in the world at home, so I would not want to buy duplicates of something i already have...

longnkrnch Enthusiast

longnkrnch

Posted
Posted

Im betting its the pump. Mine did exact same thing two years ago. Went on for about a month before the pump finally crashed. Had the new pump installed ($900 buck repair) mechanic recommended the OEM pump, and guess what. It has started doing the same thing now. I guess these pumps are just no good. I wish I could install an outside the tank pump.

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