1985 Buick Century Bucks Under Load

1985 BUICK CENTURY
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OAKLEY1
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I have an 85 Buick Century 150,000mi 2.5L TBI with an acceleration problem. Under low to modetare loads it bucks. Even with TCC unpluged. Plugs, wires, cap were replaced. Problem started soon after having ignition module replaced. While power braking and looking at the fuel injector you can see the fuel momentarily stop spraying when it bucks. Where does injector get its reference from? Could it be the ignition module, MAF sensor and if so where is it located?
Apr 18, 2007 at 9:40 AM
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RASMATAZ
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[quote:bff878f500="Oakley1"]I have an 85 Buick Century 150,000mi 2.5L TBI with an acceleration problem. Under low to modetare loads it bucks. Even with TCC unpluged. Plugs, wires, cap were replaced. Problem started soon after having ignition module replaced. While power braking and looking at the fuel injector you can see the fuel momentarily stop spraying when it bucks. Where does injector get its reference from? Could it be the ignition module, MAF sensor and if so where is it located?[/quote:bff878f500]

Check the fuel pressure-the computer has to get an ignition signal before it pulses the injectors.
Apr 25, 2007 at 2:08 AM
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OAKLEY1
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It was the ignition module. the injectors get their reference from it
Oct 25, 2007 at 5:25 AM

Suggested Repair

The confirmed cause was a faulty ignition module. The ECM needs an ignition reference signal before it pulses the TBI injector; also check fuel pressure if bucking returns.

Conversation Summary

A 1985 Buick Century 2.5L TBI bucked under low to moderate load, and the injector briefly stopped spraying. Plugs, wires, and cap had been replaced, and the problem began soon after an ignition module replacement. The expert advised checking fuel pressure and noted that the computer must receive an ignition signal before pulsing the injectors. The owner later confirmed the ignition module was the cause and that the injectors take their reference from it.

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