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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jfkelley on August 13, 2019, 04:48:34 pm
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My 76 K10 is having issues ...My son is driving it until his 77 Trans Am is finished being restored ...He came home last nigh said it was acting funny , I drove it and it cuts in and out right before the second shift and one it shifts I can hear transmission clunk , and then it will clear up not do it for awhile and my son drove it home from school and it was doing it again ...This time I drove it and it did it again but backfired a couple times and started cutting in and out..I changed the Distributor, Rotor, Fuel Filter and control module...I don't know if its a fuel delivery issue or electrical. I would appreciate anyone's input
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Took it out on the interstate , sitting at the red light to get on to the interstate and I decided to just floor it ! it never hesitated took off like a ROCKET ! didn't start cutting out until it was going to shift into drive and started cutting out almost died but all dash lights and exterior lights stayed on I let off the gas and it came back....Its acting like its not getting enough fuel , but sitting at idle I can see the fuel filter is full of clean gas...Am I looking in the wrong place thinking its the Carburetor Accelerator pump ?
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I had a bogging down issue last year. Had a cheap auto store fuel pump. Got an AC Delco fuel pump, solved issue. May not be your issue but something to think about.
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I assume when you say distributor you mean distributor cap.
Is the ground terminal on the coil making good contact with the laminations?
Hard shifts and stumbling... Have you checked the vacuum modulator on the TH350? If the diaphragm is ruptured it can dump ATF into the vacuum line. It'll also shift pretty hard at times.
Bad Modulator symptoms include...
White smoke coming out of the exhaust (ATF being sucked into the carburetor from the leaking diaphragm)
Early or late shifting.
Hard shifts (usually causing the car to jerk).
A rough idle (from the vacuum leak and ingesting ATF).
Low transmission fluid levels.
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Yes sorry meant Distributor cap ..No white smoke or anything like that coming out of the exhaust ..I will check the Ground..Thanks
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Pulled the Edelbrock 1405 off tonight went through it , found a red triangle piece of filter inside of it so I thought there’s my issue , Put it back together idle smooth went to test drive out the pedal to the metal took off went to shift into second fell right on its face and wouldn’t go over 45-50 mph Pulled the fuel line placed it in a glass mason jar , son cranked the engine over and it was a soft stream for about 15 seconds ..So off to get an fuel pump in the morning hoping this fixes the problem ..Fingers crosses
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It ended up being the Ignition modulator Inside the Distributor rain fine at warm up but once got hot start cutting out & get this the part was under warranty ! Also found an 1 inch Triangle piece of foam inside the carb..
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Very good!
Something I have done on most of my old cars, to help find these kind of problems and show it's not a ground issue (especially since the engine to cab ground is hard to get to) Is to just add more grounds. Take a decent size cable and add a ground from the cab to the frame, and from the engine to the frame. usually that takes care of most bad ground issues. You cannot have too many ground connections. If in doubt, add a ground strap. It won't hurt anything and doesn't cost much, why not?