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GM-GMC/86 gmc truck problem


Have an 1986 gmc with 305 in it all stock with 305 in it. The truck will start no problem and idle fine and does fine giving it gas in park but once u put it in gear and give it gas it dies or starts to die.the problem started out with the truck not wanting to go over 55 and has gotten worse pulled breather cap found air filter soaked in gas took it out truck ran fine for one day then started the dieing and smoking and strong fuel smell. It has a quadrojet carb with electronic choke on it.truck has had resent plugs plug wires and oil change. Please any ideals would be helpful

check for holes in your exhaust, probably closer to the manifold. this causes a drop in back pressure when the vehicle is in gear. (highly unlikely) but i had a vehicle that did this and that was the problem.

fuel pressure regulator next
fuel filter also needle valve

It also sounds like your Float is not working properly. Take your float out of the carb and shake it near you ear, if you here a swooshing sound, its bad and must be replaced. Make sure you clean that carb well too with Gumout spray carb...Wear goggles when using that stuff.

i find it scary that your air filter was soaked, that can cause a fire and ive seen that happen, sounds like a kink or clog in a line somewhere, just because it acts ok in idle doesn't mean the parts don't have fault, you will always see more of the issue when the vehicle is in gear and the throttle is pressed.

i would also go under the hood in park or neutral and give it throttle from the engine and see if you see anything happening or smell anything you u shouldn't. i did that on another vehicle and found that where a bracket holds part of the line to the fuel rail was failing and leaking, it was a part that i could tighten but still small and didnt see it until i was right there throttling that engine.  


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Alicia B


Engine, Transmission, Brakes, Fuses, Tune ups, Where is a better place to get parts, and general questions


I used to work for GM as customer service and I worked for the information history desk for them for 2 years. I have owned upwards of 25 cars 23 were GM vehicles which I did and still do fix my cars mostly myself. I do most maintenance by myself also.

I used to be a Allexperts member a while back look up Alicia R. Boutwell.

High school diploma most of my experience is just with the actual vehicles and working for the company.

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