# Hard start when warm



## faughtj (Jan 24, 2004)

I have a 2000 Silverado 2500 (new body style) with the 6.0L engine. When the engine is warm, it hesitates when starting.. kind of stumbles for a few seconds. Seems to go away when you hit the gas a little. The truck has about 93,000 miles and otherwise runs great. I've heard the individual coil packs can fail. The only related thing is that occaisionally lately, the volts have been a little lower than normal. I checked output at the battery with my meter, with the truck off & running and it seems to be in range.


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## nrn51983 (Jan 3, 2002)

I have noticed this problem in those years of trucks. First of all, DO NOT HIT THE GAS. This turns the fuel injectors OFF. That means, no fuel, no running. If the truck smokes black smoke at start up, then we might have a fuel system leak possiblyat the injectors or the fuel regulator. This usually causes a misfire at startup as well as a misfire continuously. (Not always)

Most of the time this is what I recommend: First of all, with that many miles, go ahead and replace the plugs and wires. Use ACDelco Professional Platinum plugs. They are a little pricier than aftermarket plugs, but they run better in those engines than anything else I have seen. Use a quality wireset (any brand) have the MIL light (check engine light) read and cleared at AutoZone or another auto parts store that has that service. (I assume it's on.) If you haven't cured the issue yet, the fuel system should be pressure tested at a professional repair facility. Another possibility is the ignition module failing. I am not really confident that that is the problem as ignition modules tend to make a continuous misfire condition. (MIL light would be on steady and probably flashing).

I hope this helps and if you need any other advice, email me. Good luck! 
Nathan Norman
[email protected]


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## nrn51983 (Jan 3, 2002)

*Correction*

I misread your statement. Hitting the gas pedal only shuts off the injectors when the engine is not started, yet. I am strongly leaning towards a basic tune up for your truck. The voltage drop could just be from the lower RPM's due to a misfire. If you're not noticing a dead battery in the morning, or no "whining" noise under the hood, you probably have nothing to worry about yet. Just get the engine tuned up and you'll be sucking gas and hauling...tail.

Sorry and good luck!

Nathan Norman


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## faughtj (Jan 24, 2004)

Thanks for all the insight, Nathan. I was leaning towards plugs / wires as well as a starting point. The funny thing is that the SES light is not on.. it was coming on over the winter months pretty frequently. I have a basic code reader that will also clear the code. It was showing 157/158 which both deal with one of the post converter O2 sensors. But it doesn't come on anymore with the warm weather.  I'm wondering still about the voltage drop.. driving home last night, the volts were right about 12, where they're normally a hair over 14V. And the lights were dimmer than usual. No problem cranking in the morning though. I might upgrade to a 130 amp alt. anyways, might kill two birds with one stone. Thanks again for the help - Jason


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## nrn51983 (Jan 3, 2002)

*Chevy truck problem*

You could do what I tell my import racing friends....TURN DOWN THE STEREO!!!! - Just kidding... You got me a little stumped on the voltage drop. Remember, voltage and amperage are 2 different things. A larger Amp alternator may or may not cure the problem. (Especially if it is a voltage draw from somewhere else in the truck.) A larger amp alternator isn't a bad idea though if you are plowing snow and have warning lights, headlights, radio on, etc. Can't hurt to try!! (well, I guess it could hurt your pocket book! :realmad: ) Good luck!


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## faughtj (Jan 24, 2004)

*Update*

I replaced the plugs & wires.. I used AC Delco 41-985 Irridium plugs with Accel 8mm silicone wires. It seems to run a little stronger, but I've still got the warm start problem. I picked up a new battery, mainly because I've been wanting a larger one (went from a 75 to a 78) for next plow season, but I won't have time to install it until tomorrow. I've also replaced the alternator which solved my low voltage problem. My hard starting problem was never a slow crank, but it cranks & won't fire unless I hit the gas a few times. Used to just fire right up. Any other ideas you might have? Thanks, Jason


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## faughtj (Jan 24, 2004)

*Oh yeah..*

almost forgot, replaced the air filter too.


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## William B. (Jul 22, 2004)

A buddy of mine had a similar problem with his 98 350. It ended up being his fuel pump. The mechanic said that the truck needs x amount of pressure to start the motor and with the pump getting weak, it would start hard when it was warm. Just my $.02 work.

William


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## faughtj (Jan 24, 2004)

*Another update.. solved!*

Just thought I'd check back in case anyone needs to reference this.. the problem turned out to be my fuel pressure regulator. Another guy over on the Silverado forum on Edmunds had a similar problem and the regulator fixed his. So, I picked one up and it fixed my problem too. Cost me $54 and it's not much bigger than a few quarters stacked together! Anyways, easy install, truck fixed, now just waiting for winter!


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