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bucking and misfiring


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My truck idles fine and has plenty of power, but when I hit around 2000-2500 rpms...right before I shift it starts bucking and jerking slightly. Once up to highway speeds it does it when I let off the accelerator. If I give it gas it goes away until I slightly let off the gas. If I completely let off the gas quickly, it's not as bad. During the last several weeks while getting the truck drivable, I've replaced the CPS, ignition coil, distributor, checked the TPS, new plugs, plug wires, fuel filter and fuel pressure regulator.

 

I thought maybe catalytic convertor, so I climbed underneath and found it was put on in Dec. 02. don't think it would be plugged up yet??

 

Any ideas???? :wall:

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I disconnected the cat and that didn't help, so I rechecked and readjusted the TPS. It still does it at around 2000 rpms or if letting off the throttle. I'm wondering if I need to pull the fuel pump and check the sock.

 

My other question is: when I bought the truck the knock sensor was missing the cover, sensor is there, but no cover. I have read on here that some guys don't even have theirs hooked up and run fine. Could this cause it to buck? :mad:

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Just my luck....now I have more issues..... bought a knock sensor and put it on. Before I tried to fire it up I dropped the lower dash and taped several bundles of wire, checked out the ECU and unscrewed the fuse panel to see if any clutch fluid had been leaking there. Put everything back together and dropped the fuel tank. Emptyed the tank and pulled the fuel pump, then put a new sock and hoses on. Got everything together and turned the key.....no pump noise.

 

I thought maybe I blew the relay, so I grabbed the meter and checked the harness at the pump- 7 volts. I was careful with the pump, so I don't think I damaged it. Here's the weird thing....when I touch the brake pedal or turn on the headlights I hear the pump faintly running-just not at full power. Also when the brake is pressed a loud chime noise is heard (like the door open, but louder). I looked at the wires and fuse box that I messed with before, but don't see anything wrong.

Seems like maybe a ground issue??

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Jumped into the wiring today and started at the tailight. Looked in the harness and lo and behold...a ground wire that had been cut. Replaced end and hooked up ground. Now when I turn key I have nothing but the chime module. I split the fuse box in half and have power to the firewall, but nothing at the fuse box. Has to be a short, but not sure where to look first. HELP!!!!! :wall:

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