Question about 1991 GMC C1500

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I have 96 gmc 1500 vortec v8 that misfires on cylinder #6 and it idel's high all the time and the vacuum system is off

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For your idel problem run mid grade gas

Posted on Aug 05, 2008

  • 1966 NOVA Aug 05, 2011

    I had a cold start up miss on my 97 Vortec and had suspected a head gasket or cracked head because it would clear up after it warmed up . I had noticed that the plug on #6 had white deposits on it leading me to suspect that it was coolant .I found another person had posted the same symptoms as those I had experienced and found the problem to be a vacuum leak on the intake gasket on Cyl 6 . Bingo I blocked off the PCV valve and blocked the tube off of the inlet to the Right side valve cover . I started the truck and put my thumb over the hole in the valve cover and that confirmed that there was a vacuum in the crank case . The vacuum leak caused cyl #6 which is the reason for the white on the plug . It disappeared when the eng warmed up and the gasket expanded enough to stop the leak . I replaced the intake gaskets with Felpro Ultra Dry and that has completely solved the problem . It's been a year now and wish I could have had the correct diagnosis right away . This may not be your problem , but it is another thing you can look into and maybe at least rule it out . Good Luck

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1 Answer

Cylinder 6 is misfiring. What was will fix this problem? It's a 5.7L v8 in a Chevy 1500.


You don't say what year the truck is, so I will guess on the fuel system.
You need spark, fuel, and compression for the cylinder to produce power. One of the three is missing.
If the engine has multi-port fuel injection the injector for that cylinder could have failed.
Could also be a plug, plug wire, or something mechanical.

Aug 12, 2013 | Cars & Trucks

1 Answer

Random misfire cylinder 3


Smoke test entire vehicle for vacuum leaks

You don't have any idea where the misfire
is from, at this point,find out

You installed parts

That is not what you do,you diagnose & find
the cause of the misfire,no parts involved there

You don't have the professional tools or software
at home, to diagnose without wasting time & getting
no where

Could have a bad intake gasket or mechanical problem
in one cylinder

Apr 04, 2013 | 2001 Chevrolet Silverado 1500

1 Answer

1996 chey silverado 1500 truck its misfireing what could be the problem


probally check the timeing on the distributor cap had my cap go bad numerous times same truck 96 350 vortec

May 18, 2012 | 1999 Chevrolet Silverado 1500

1 Answer

2003 GMC Sierra Has recently developed rough idle/lope at idle which sometimes goes away. Runs fine otherwise. Scan codes-Lean condition bank1 and bank2. Random misfires on all cylinders. Fuel pressure...


You never replace anything, on a Wishing,Hoping,Pushing,Poking,diagnostic approach

You learn the vehicles Systems,Test,then Replace,if you have a failed component.

Work on the Misfire Issues.
Then you lean O2 Codes will go away.

Not a the plugs.

Think lean---Vacuum leaks,EGR Valve leak,EVAP System leaks,anything with a hose that lets air into the intake system.
Exhaust System leaks,near sensors

Nov 24, 2010 | 2003 GMC Sierra 1500

1 Answer

I need the firing order of 1996 gmc engine sierra 5.7liter vortec


For the 1996 GMC SIERRA with 5.7L V8:

Firing Order:
1-8-4-3-6-5-7-2

Cylinders:
.........(back).........
|...8...|........|...7...|
|...6...|........|...5...|
|...4...|........|...3...|
|...2...|........|...1...|
.........(front)

Distributor Connections:
............(back)
Coil--->o
6------->o........o<-------5
4------->o........o<-------3
2------->o........o<-------7
8------->o........o<-------1
.............(front)

Let me know if this helped, or if you have additional information or questions. Feel Free to contact me at FixYa.com!

May 30, 2010 | 1996 GMC Sierra

3 Answers

I own a 96 chevy k1500 5.7 l vortec and have a no 5 cyl misfire


It could be a faulty fuel injector, try running a fuel injector cleaner through your fuel system. At worst the poppet nozzle has gone bad and will need to be replaced, you can buy the poppet nozzle it self individually at Auto Zone or buy upgrade MFI system which is much better and less pron to fuel leaking room a cracked poppet line or nozzle which will cause what you have described.

Feb 03, 2010 | 1999 Chevrolet Silverado 1500

1 Answer

Fluid specifications and quantities for 99 silverado


You did not give your engine size or other information, but here is a list from the handbook...

Cooling System Capacity (Approximate)
VORTEC
4300 V6
Automatic 12.6 quarts (11.9 L)
VORTEC
4300 V6
Manual 12.9 quarts (12.2 L)
VORTEC
4800 V8
Automatic 13.4 quarts (12.7 L)
VORTEC
4800 V8
Manual 13.7 quarts (13 L)
VORTEC
5300 V8
Automatic 13.4 quarts (12.7 L)
VORTEC
5300 V8**
Automatic 14.9 quarts (14.1 L)
VORTEC
6000 V8
Automatic 14.8 quarts (14 L)
VORTEC
6000 V8*
Automatic 14.4 quarts (13.6 L)
VORTEC
6000 V8
Manual 15.2 quarts (14.4 L)
VORTEC
6000 V8*
Manual 14.8 quarts (14 L)
VORTEC
5300 V8**
Automatic 14.9 quarts (14.1 L)
VORTEC
6000 V8
Automatic 14.8 quarts (14 L)
VORTEC
6000 V8*
Automatic 14.4 quarts (13.6 L)
VORTEC
6000 V8
Manual 15.2 quarts (14.4 L)
VORTEC
6000 V8*
Manual 14.8 quarts (14 L)

Crankcase Capacity (Approximate)
VORTEC
4300 V6
W 4.5 quarts (4.3 L)
VORTEC
4800 V8
V 6.0 quarts (5.7 L)
VORTEC
5300 V8
T 6.0 quarts (5.7 L)
VORTEC
6000 V8
U 6.0 quarts (5.7 L)

Fuel Tank Capacity (Approximate)
Short Bed 26 gallons (98 L)
Long Bed 34 gallons (128 L)
Chassis Cab 34 gallons (128 L)

Apr 03, 2009 | 1999 Chevrolet Silverado 1500

2 Answers

98 chevy 1500 4.3L vortec misfire problem


These have a real problem with the distributor caps, i would try that

Feb 18, 2009 | 1998 Chevrolet C1500

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