hard start when warmed up 99 silverado 5.3

Asked by Nov 30, 2012 at 05:38 AM about the 1999 Chevrolet Silverado 1500 3 Dr LS Extended Cab SB

Question type: Maintenance & Repair

MY SILVERADO PICKUP STARTS GREAT WHEN COLD BUT WILL NOT START WITH OUT CRANKING FOR PROBABLY AROUND 6 SECONDS. SOMETIMES MORE AND SOMETIMES LESS. IT WILL START BACK UP EASILY RIGHT AFTER YOU SHUT IT OFF BUT ABOUT 5 MINUTES LATER IT WILL NOT START VERY WELL.
MY CRUISE QUIT ALSO, DON'T KNOW IF IT HAS ANYTHING TO DO WITH IT. I HAVE CHECKED ALL FUSES, REPLACED FUEL PUMP AND FILTER. TOLD MAYBE IT COULD BE THE TPS, ANY IDEAS?

16 Answers

34,985

Check to see if the cruise control is vacuum operated. There might be a vacuum diagram under the hood.

7 of 7 people found this helpful.

My Toyota does the same thing, and I don't know why, best guess is fuel is not pressurized right, and is there a 'check engine' light on? Does it run well otherwise? To me it is a minor problem that is not worth spending money to fix, as long as it does not get worse and does start every time.. As for cruise control, I don't see how that would be related. Sorry i didn't help you, not a real answer. 5-6 seconds is not that long to crank, although it should indeed not do that, but if it does start every time, I wouldn't worry about it. Good luck. Now this is just me, but I have a difficult time reading all upper case. The only thing I can think of is check fuel pressure on rail, to see if it is where it should be 5 minutes after you shut it off. It may be low at all times and this is a symptom of something else. Run a scan, free at AutoZone and see what pops up if anything Please get back and let me (us here on the forum) about if it runs OK and gets decent MPG, and how long has this been going on? Thanks K6

4 of 4 people found this helpful.
34,985

It feels like we are being yelled at.

2 of 2 people found this helpful.

John got that in while I was typing , listen to John he knows what he is talking about. I found a vacuum diagram but no use to post it, impossible to see.

2 of 2 people found this helpful.

I did find a fuel rail if you want to check pressure

5 of 5 people found this helpful.

That helpful click was me, I agree 100% I was trying to be tactful with the guy

2 of 2 people found this helpful.
34,985

Odds are slim but if the vacuum line to the cruise control is bad it will prevent it from working and may also mess with the engine when its warmed up because its still in closed loop mode. When its cold it is in open loop mode and by default would add extra fuel possibly neutralizing the effects of the small vac leak. As it warms up the idle air control adjusts to this vacuum leak and when the key is off the idle air control resets itself causing a hard start up due to the vacuum leak not being compensated for. Just a possibility

3 of 3 people found this helpful.

K6, see what I mean by listen to John? Everything he just posted I did not know and learned, by paying attention, one of the reasons I participate in this forum, to learn as well as help

34,985

Also as david said fuel pressure could be low and the computer would do the same thing with the fuel as it does with the air. Starts fine cold because its in open loop and using extra fuel to run but once its in closed loop with the idle air control reset there just isn't enough fuel to start right away. One way there is too much air and the other would be not enough fuel. The cruise could be a fuse, have you checked fuses?

1 of 1 people found this helpful.

All of the answers sound logical. I will do some testing and get back. I have checked all fuses changed fuel pump and filter. The reason for the fuel pump was because my 03 chevy 6.0L was doing the same thing and that is what it took. And it was something I could do fairly easily.

Cruise control switch.operating device, It's much too complex to be called a switch

2 of 2 people found this helpful.
30

I changed out my fuel pressure regulator and it fixed this problem for me. Cheap $50-60 DIY fix. Hope this helps. I had a hard start problem, but it was always great first shot in the morning. Takes 3 or 4 after that. After replacing the regulator this was fixed.

3 of 3 people found this helpful.
10

Im not the best with CHevys but my suggestion is change the fuel pump rellay in the main fuse block. Its usually under the hood by the firewall or along a fender. My experience comes from a 90 Jeep Wrangler that did simalar things after a year or so and about 3000 bucks in shop fees it started shutting down when driveing and started again when it felt like it. I finally did enough looking into the wireing and everyother scamatics I could find and reallized it was shutting down my fuel pump and my injectors all at the same time. It was a 20 dollar fix.

1 of 1 people found this helpful.

2005 6.0 diesel starts well runs well on first startup when it warm wont start im thinkin crank sensor....or tps maybe what do you think

no answers about a 2005 6.0 diesel?

20

I have a 02 silverado 4.8 ex cab 4x4 its easy to start after sitting over night and right after i shut it off but after sitting for a little bit hard to start crank crank crank for about 6 seconds i think its a fuel problem but i put new injectors new filter 2 fuel pumps 2 fuel regulators new maf new plugs and wires crank sensor but i havent done the relearn procedure could that be the problem

2 of 2 people found this helpful.

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