1988 cutlass ciera boggs down. Acts like a carburetor engine with a bad accelerator pump. it boggs doen when i accelerate from a stop then when i just barely mash down i can slowly get it up to speed. replaced crankshaft sensor. corrected that but it started to shudder, vibrate, hard to explain at low load cruse, about 45 mph, in overdrive, and up. rev it up thru the gears and it will go 70 mph plus and not miss a beat. drop it back to cruse and light load and it will shudder. It does not throw a code. replaced fuel filter, throttle position sensor, plugs and wires, tested module. replaced crankshaft sensor with a different brand and now i am back to the original problem. HELP!!!! thanks for any help you can give me.
Hello! You have symptoms that point to incorrect fuel pressure.
First have the fuel pressure tested as follows; #1...engine running at idle: 13- 20 psi. #2...key on engine off: 23-30 psi. If pressure is incorrect change the fuel pump.
Does the engine "surge" at idle? If so, check the "fuel injection pressure regulator idle air control valve". Apply a vacuum to it; If fuel flows it is not the problem.
Guru.............saailer
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I forgot to list the fuel pressure check we did.Fuel pressure is 34 to 38 # key on and 28 # running. With vacuum line removed from regulator the pressure goes to 40 #. It holds the pressure five minutes or longer with key off with no drop in pressure.
Thanks again for any help.
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