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745 not responding on full trottle[850/1995] posted by Roger Sundelin on
Saturday, 28 March 1998, at 4:45 p.m.
Hi there
I have a problem with my 745 1990 B200F with LH-Jetronic fuel injection.
It seems to choke on full trottle,and when rising the trottle a bit it runs fine.
The car has just been to the Bosch-center, and they said it was okay. I have
a different opinion.
Any ideas about where to start looking?
Roger Sundelin
Finland
Re: 745 not responding on full throttle[850/1995] posted by R. Abel on
Sunday, 29 March 1998, at 9:54 a.m.
Did they check the throttle position switch? It should give different responses
for idle, intermediate, and full throttle positions.
Next, does it act fuel starved? Does it respond differently when gas tank is
full compared to 1/4 tank? (Are either the air or fuel filters aged?)
If you had a fuel pressure guage, it might be
informative to view the fuel pressure under the conditions you describe.
good luck. pls inform us as to resolution.
Re: 745 not responding on full trottle[850/1995] posted by Steve Seekins on
Sunday, 29 March 1998, at 6:49 p.m.
I would recommend that you check the throttle plate. The LH Jetronic system depend on an air mass meter to determine the correct amount of fuel. If the throttle plate does not open all the way, it will limit the amount of air that gets into the engine, and hence the power. Remove the Hose from the throttle body, and have someone depress the foot feed all the way down inside the car. Watch the throttle place with a good light and an inspection mirror to make sure that it opens until exactly parallel with the bore. IF it opens more or less, you need to make adjustments. Check to make sure nothing is restricting the movement of the accelerator pedal. Check to make sure that the throttle linkage pulley is going from idle stop to full open stop - i.e., that it is operating through its full range. If so, and the throtle plate is still not opening fully, the you must bend the lever arm on the throttle plate shaft slightly. Bending it forward (away from the throttle body) will efectively shorten the arm so that the same amount of motion of the link rod will move the throttle plate further. It only needs to be bent slightly to have a significant effect. Double check everything.
Another possiility is that there is a problem with the fuel pressure regulator. Make sure that the vacuum line is properly increasing the fuel pressure as the manifold vacuum drops.
Volvo Club of America