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Hard Cold Start - 03 Suburban #5233488 10/08/19 12:24 AM
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Fitz98 Offline OP
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My 2003 Suburban 5.3 1500 around 100k miles has started an new thing over the last few days.
Used to start right up without hesitation, but recently on cold starts (engine cold, not climate cold...I am in Florida) it takes a few seconds and a few cranks to get started. Once it starts it runs great, smooth, no skips or power loss.
Any ideas what to start to look for?

Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233510 10/08/19 02:54 AM
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Gasbuggy Offline
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The fuel pump isn't holding pressure. Common GM issue. Is the fuel pump original? 100k is about the max life span for one.


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Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233527 10/08/19 04:07 AM
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billt460 Offline
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My 91 F-150, 5.0 started doing the same thing. A gave it a good tune up. Plugs, wires, rotor, cap, and a new coil. Along with new fuel and air filters, and it cured it. Now it fires right up when cold. (Same as you, engine cold not climate cold. I live in Arizona).

Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233668 10/08/19 08:29 AM
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Fuel Pressure Regulator

Re: Hard Cold Start - 03 Suburban [Re: Gasbuggy] #5233669 10/08/19 08:32 AM
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AVB Offline
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Originally Posted by Gasbuggy
The fuel pump isn't holding pressure. Common GM issue. Is the fuel pump original? 100k is about the max life span for one.

That was my first thought.

Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233785 10/08/19 11:12 AM
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Tman220 Offline
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Intake manifold bolts are torqued to very low values. overtime, the intake manifold o-ring gaskets lose their elasticity and preload is lost. This results in intake manifold gasket air leaks. Once running, manifold vacuum tends to be enough to seal things back up and run fine.


2012 Regal GS Turbo PP 5w30 90k
1994 Camaro Z28 LT1 355 CI, 430 RWHP PP 5W30 165k
2005 GMC Sierra 1500 5.3 160k
2004 Civic LX M5 178k
2007 Camry 2.4 232k
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Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233793 10/08/19 11:16 AM
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mk378 Offline
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You could try clicking the key on and off a couple of times to prime the fuel lines before trying to start. If that helps, it is either the anti drain back valve in the fuel pump, or the fuel pressure regulator.

Re: Hard Cold Start - 03 Suburban [Re: mk378] #5233805 10/08/19 11:27 AM
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billt460 Offline
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Originally Posted by mk378
You could try clicking the key on and off a couple of times to prime the fuel lines before trying to start. If that helps, it is either the anti drain back valve in the fuel pump, or the fuel pressure regulator.

That's what I was going to suggest. When I did that with mine, it didn't help it start any sooner. The tune up did.

Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233845 10/08/19 12:16 PM
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billt460 Offline
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I should add that after I changed the fuel filter, I switched the key on and off about 4 times, and it fired right up. It stumbled a bit after starting, but kept running. After a few seconds of this it smoothed right out. So I'm assuming the fuel pump, valves, and regulators are all doing what they are supposed to.

Re: Hard Cold Start - 03 Suburban [Re: krismoriah72] #5233874 10/08/19 12:41 PM
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The_Eric Offline
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Originally Posted by krismoriah72
Fuel Pressure Regulator


They usually cause hot start issues


2005 Lincoln Aviator 4.6 DOHC
2000 Honda Accord 2.3
2001 Hyundai Elantra 2.0
1979 Ford F-150 351M
Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233877 10/08/19 12:44 PM
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mk378 Offline
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You're missing the point. The fuel lines are supposed to stay full while the truck is parked. If the fuel drains out, the next start (by simply turning the key once normally) would take more cranking time. The test is to prime the lines first to see if they have drained out or not.

Re: Hard Cold Start - 03 Suburban [Re: mk378] #5233882 10/08/19 12:50 PM
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The_Eric Offline
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Originally Posted by mk378
You're missing the point. The fuel lines are supposed to stay full while the truck is parked. If the fuel drains out, the next start (by simply turning the key once normally) would take more cranking time. The test is to prime the lines first to see if they have drained out or not.


Was that for me?


2005 Lincoln Aviator 4.6 DOHC
2000 Honda Accord 2.3
2001 Hyundai Elantra 2.0
1979 Ford F-150 351M
Re: Hard Cold Start - 03 Suburban [Re: billt460] #5233906 10/08/19 01:28 PM
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mk378 Offline
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No it was in response to this.
Originally Posted by billt460
I switched the key on and off about 4 times, and it fired right up.... So I'm assuming the fuel pump, valves, and regulators are all doing what they are supposed to.

Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5233909 10/08/19 01:32 PM
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Fitz98 Offline OP
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Thanks for the feedback, I did a cold start by trying the turning key on and off 4 times before cranking and it started right up, so sounds like fuel system is losing prime.
If it is stuck check valve, is there any fuel additive that might help free things up?
Any other ideas what to look for before dropping tank to replace fuel pump?

Re: Hard Cold Start - 03 Suburban [Re: Fitz98] #5234090 10/08/19 05:19 PM
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Gasbuggy Offline
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Originally Posted by Fitz98
Thanks for the feedback, I did a cold start by trying the turning key on and off 4 times before cranking and it started right up, so sounds like fuel system is losing prime.
If it is stuck check valve, is there any fuel additive that might help free things up?
Any other ideas what to look for before dropping tank to replace fuel pump?


Nothing you can do to mask this issue. Although, the long crank when cold isn't hurting anything. Please, do yourself a huge favor, and buy the AC Delco pump assembly when you replace it. If things look too rusty under there, I've pulled the back seat and carpet out, cut an access panel and the Panel Bonded it back together. Makes for a much easier replacement when your other option is working on your back.


Cadillac CTS-V 6.2L 10w30PP
Volvo P1800 Euro L
76 Mercedes 300D Rotella T4
Series III Land Rover VWB
02 Yukon 10w30 PP
01 P71 M1 EP-HM 0W20
95 Accord - 386k. Mobil 2 RIP
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