I have a 1991 GMC 1500 pickup and most of the time when i accelerate white smoke comes out of the exhaust pipe and it leaves a pretty bad smell, i just had a full tune up done on it.

SOURCE: 1991 gmc sierra and white smoke

head gasket blown, or cracked head.

coolant is making its way to the piston and combusting with the gas.

1 or both routes are the only possible way.

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SOURCE: 1988 gmc 1500 Gas smell coming from tail pipes

running rich?. make sure your air cleaner is clean the filter is clean. how old are plugs, wires, cap, rotor, o2 sensors? also you feul injectors could be leaking extra feul into the engine. run the engine with the air cleaner off. let it warm up. shut off. look at the injectors with a light to see if they are leaking. does it burn alittle on whenb you first start it?

SOURCE: 1998 gmc 1500, 192000 km.

most likely the knock is a valve lifter, could be caused by a few things but lets start with trying to add some seafome to the engine oil and see if the knock goes away in a day or so,if it does change the oil and continue with the seefome with each oil change, if the knock does not go away then things get a little more complicated, the first thing would be to get an oil pressure reading at the oil pump. if low or no pressure then you will need to at the least replace the oil pump at the worst replace the engine, i think the smoke is only at start up? if it is then it is valve seals, and the seafome will also help with this. if the engine has good oil pressure then you will most likely have to replace the valve lifters.....

let me know if there is any thing else i can do for you.

Stephen

• 21873 Answers
• Posted on Aug 28, 2012

SOURCE: 1999 gmc suburban-smoke comes out exhaust and smells like gasoline

If the check engine light is not on, I would check the fuel pressure regulator and for problems with the fuel return line.
If you have a leaking injector you should get a check engine light and code for a cylinder miss.

SOURCE: 1992 GMC 1500 pickup

that should have throttle body fuel injection run the engine with the air filter off and watch the injectors spray fuel to see if there a cone shaped spray if ok check the fuel pressure i have seen the regulator rupsure and the fuel dumps into the engine