1999 ck 1500 truck random misfire

Patrick · 05-01-2006, 01:09 PM

I have a 1999 new body style silverrado 5.3
service Eng. light is on & off the last four days?

Thing I have done?>>>>>
1) I have installed new plugs and wires.
2) Cleaned the throttle body out and sprayed carb. cleaner in it. Ran OK for 8 miles then the service eng. light comes back on after being cleared twice.
3) I Checked the fuel pump pressure & the fuel sample all OK.
4) put carb. cleaner in the fuel tank.
5) pulled the power on each injector to see which one is bad not sure on this one?

Questions.
1) Could it be dirty injectors?
2) anyone run Seafoam?
3) Not sure again Fuel pressure Regulator?

Misfire on # 7 like 3000 times and mising on some of the others not as bad.
Anyone that has any ideas please feel free to help me out HERE!
Thanks
Patrick

mudseeker · 05-02-2006, 05:57 AM

pull the code to see what it's trying to tell you and go from there.

Lunendan · 05-03-2006, 05:02 PM

I have a 00 silverado 5.3 with 97k miles that I recently acquired. My truck also has a random misfire. I can't tell if it's one or multiple cylinders but it's definately much worse at about 1200rpms than idle. My truck does not set the check engine light though. I changed my plugs & wires and did other stuff such as air, fuel, pcv, oil filter. The plugs and wires had no affect. I did a compression test and all cylinders are equal and good. It also passed massachusetts inspection where they check the computer for any problems. The inspection guy said I probably need a fuel injection service which flushes the injectors. My truck seems to run lean, pinging on moderate load, so maybe he's right. I have no problem spending a couple hundred to fix the problem but I don't want to use my wallet to "experiment." I just found this forum and am hoping that this misfire/skip is commonly seen with a simple solution. Any help is greatly appreciated.

Lunendan · 05-04-2006, 06:53 PM

Noone has seen this problem?! Help!

chevyguy · 05-05-2006, 12:20 PM

Sounds like a coil pack. Need to have codes pulled.

Lunendan · 05-09-2006, 04:51 PM

Patrick, I did a fuel pressure test today and I'm only getting about 43psi. The dealer spec for fuel pressure for a vortec 5.3 is 58-65 psi. So I clamped off the return line and no change so the pump is beginning to fail. This may explain my problem. I will let you know what happens when I change the pump. You may want to check your pressure.

lithopro · 05-10-2006, 09:57 AM

it could be an O2 sensor which in turn could be a "misfire" problem too. You're not actually misfiring, just not getting enough fuel. But hey, what do I know.

bowtieman · 05-24-2006, 07:53 PM

hi, i had a 99 chev truck with 5.3L,and i had the same problem it turned out to be one of the coil packs check that out.

chevyguy · 05-25-2006, 10:19 AM

I am still leaning to coil packs. No guarantees without checking the codes though.

05-01-2006, 01:09 PM	#1
Patrick Junior Member Join Date: May 2006 Posts: 1	1999 ck 1500 truck random misfire I have a 1999 new body style silverrado 5.3 service Eng. light is on & off the last four days? Thing I have done?>>>>> 1) I have installed new plugs and wires. 2) Cleaned the throttle body out and sprayed carb. cleaner in it. Ran OK for 8 miles then the service eng. light comes back on after being cleared twice. 3) I Checked the fuel pump pressure & the fuel sample all OK. 4) put carb. cleaner in the fuel tank. 5) pulled the power on each injector to see which one is bad not sure on this one? Questions. 1) Could it be dirty injectors? 2) anyone run Seafoam? 3) Not sure again Fuel pressure Regulator? Misfire on # 7 like 3000 times and mising on some of the others not as bad. Anyone that has any ideas please feel free to help me out HERE! Thanks Patrick

05-02-2006, 05:57 AM	#2
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 6,374	pull the code to see what it's trying to tell you and go from there. __________________ i'd rather be hunting

05-05-2006, 12:20 PM	#5
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,370	Sounds like a coil pack. Need to have codes pulled. __________________ Friends dont let friends use body lifts USMC 92-96 USCG 98 to present

05-10-2006, 09:57 AM	#7
lithopro Full Member Join Date: Feb 2006 Posts: 25	If you're running lean it could be an O2 sensor which in turn could be a "misfire" problem too. You're not actually misfiring, just not getting enough fuel. But hey, what do I know.

05-25-2006, 10:19 AM	#9
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,370	I am still leaning to coil packs. No guarantees without checking the codes though. __________________ Friends dont let friends use body lifts USMC 92-96 USCG 98 to present

05-03-2006, 05:02 PM	#3
Lunendan Junior Member Join Date: May 2006 Posts: 3	I have a 00 silverado 5.3 with 97k miles that I recently acquired. My truck also has a random misfire. I can't tell if it's one or multiple cylinders but it's definately much worse at about 1200rpms than idle. My truck does not set the check engine light though. I changed my plugs & wires and did other stuff such as air, fuel, pcv, oil filter. The plugs and wires had no affect. I did a compression test and all cylinders are equal and good. It also passed massachusetts inspection where they check the computer for any problems. The inspection guy said I probably need a fuel injection service which flushes the injectors. My truck seems to run lean, pinging on moderate load, so maybe he's right. I have no problem spending a couple hundred to fix the problem but I don't want to use my wallet to "experiment." I just found this forum and am hoping that this misfire/skip is commonly seen with a simple solution. Any help is greatly appreciated.

05-04-2006, 06:53 PM	#4
Lunendan Junior Member Join Date: May 2006 Posts: 3	Noone has seen this problem?! Help!

05-09-2006, 04:51 PM	#6
Lunendan Junior Member Join Date: May 2006 Posts: 3	Patrick, I did a fuel pressure test today and I'm only getting about 43psi. The dealer spec for fuel pressure for a vortec 5.3 is 58-65 psi. So I clamped off the return line and no change so the pump is beginning to fail. This may explain my problem. I will let you know what happens when I change the pump. You may want to check your pressure.

05-24-2006, 07:53 PM	#8
bowtieman Junior Member Join Date: May 2006 Posts: 3	hi, i had a 99 chev truck with 5.3L,and i had the same problem it turned out to be one of the coil packs check that out.

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