Mechanics

STUTTERS ON HARD ACCELERATION. WHY?

1991 Volvo 240 • 223,786 miles

I have a 1991 volvo 240 non turbo that I am restoring. It runs and drives very well but when accelerating is hesitates and stutters for about 1-2 seconds. Once its done then your really cooking. Is it an ignition problem or something else? Thanks for your help.
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Jeepguy
February 28, 2012.




It could be a clog in the intake or exhaust tract. Sometimes catalytic converters fail and fall in on themseklves and clog the exhaust.
It sounds like you have more of a fuel management problem thoguh. Check the fuel pressure and the filter.

Ok if that is the issue wouldnt it always be stuttering? Just seems odd that once it stops it runs perfectly. Havent gotten to change any ignition components yet. Maybe that should be my next step.
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Tiny
Jeepguy
Feb 28, 2012.
Well when the throttle is pressed the fuel pressure regulator is actuated by vacuum to increase pressure for the higher RPM demand. If the regulator, vacuum line or fuel pump are weak, it will hesitate as the fuel pressure tries to catch up via momentum. You might also have a dirty throttle body and/or injectors. Try running some good fuel system cleaner like BG44K, you have to go to a car dealership to get it and it runs $20+ a bottle but it is the only cleaner that works. If you can't get that get some SEA FOAM. Run a can or two in two tanks of gas and be ready to change the oil after you run a third tank of gas to really get the deposits out. It will remove so much from a dirty engine that the oil will need chaning as that is where the depositis end up.
I am certainly not saying that you don't have a bad plaug wire or something but it just sounds like it's not getting fuell or air. One of the two. If it was not firing the ignition right you would get more backfires and pops. But this is all a process of elimination and the starting point can make a difference. You have the car inffront of you and have a better feel for what might be the issue. You also know more about it as you drive it everyday, or not. If it has sat for a long time with gas in it without running, the fuel problem might be more likely. If it has not had ignition components replaced then that bumps that up on the scale of likely sources for the problem.
We will get it figured out. Cars can do some strange things when they are running but not running just right. There easier to diagnose when they are in really bad shape. Your car is not and it will take some time and luck and logical elimination to find something that works. Just not perfectly.


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