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Discussion Starter · #1 ·
Truck idles fine. Start to go down the street and it feels like it is starving for gas. (366 gasoline engine.) So far we have replaced the plugs, wires, rotor cap and button, fuel pump, fuel preasure regulator, and cleaned the carborator. This truck has been down for a month now and I'm giving up.:( Any help would be greatly appreciated.

97 GMC C7500
366 motor
 

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Is it fuel injected ? if not you probably will need the carb rebuilt...
 

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Fuel, air, spark, compression. Always check the basics. This has been down for a long time. It is easy to get frustrated and forget things, or to make assumptions. You've changed a lot of parts, but haven't found the problem. Go back, forget everything you have done, and start over. Did the problem happen suddenly or gradually? Suddenly is a broken part, gradually is dirty or worn. Check compression, timing, fuel. Also, air comes in the front, out the back. Some ***hole could have shoved something up your exhaust. Truck will start, but won't have power. Shine a light up there. Cat could be plugged if it has one. Check vacuum lines.

Of course, since it doesn't run, I could take it off your hands, $500 cash right now.:D
 

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Do I hear a thousand thousand ???
 

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Discussion Starter · #7 ·
already ripped the cat conv. off ( it weighed about 100 pounds)
Compression is ok
Timmings getting checked tomorrow.
 

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does it have a holley carb or a quadrajet carb
 

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mike really sounds like it could be a plugged venturi in the carb
 

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Discussion Starter · #12 ·
Final Verdict.

A hole in the exhaust manifold gasket let heated air get through and melt a plug wire inside the heatshield causeing the truck to run on 7 cylinders.

It just seems so simple now:damputer
 

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Discussion Starter · #14 ·
yes the plugs and wires had been changed not to long before this problem started. Maybe a month before. So we thought they were fine until closer inspection showed that one of them had been heated so much that the outside cracked apart causeing the connection to be severed from the spark plug and then the plug wire was arking off the manifold causeing the truck to miss. So a new gasket, bolts, plugs, wires, fresh tank of gas and it seems to be running great. Cross the fingers:wink
 

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Truck idles fine. Start to go down the street and it feels like it is starving for gas. (366 gasoline engine.) So far we have replaced the plugs, wires, rotor cap and button, fuel pump, fuel preasure regulator, and cleaned the carborator. This truck has been down for a month now and I'm giving up.:( Any help would be greatly appreciated.

97 GMC C7500
366 motor
TPS?
 

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Well I am having issues with my 97 C7500 GMC Topkick 6.0 ltr. It idles fine after warm up, I do smell alot of fuel upon ignition and backfiring or missing. It idles alright after that. When gearing down to a stop it backfires, not loud. It does stall out around corners at times. Sometimes I belive it chokes itself out because you can smell the fuel. I've had the distributor replaced, coil, wires, etc. Any ideas?
 
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