• Tiny
  • Munciefan
  • 1992 Chevrolet Silverado

Engine Mechanical problem
1992 Chevy Silverado 6 cyl Two Wheel Drive Automatic 190000 miles

OK, so I have a 1992 chevy silverado 4.3l 220 rochcester TBI w/ a 700r4 auto, about 2 months the fuel pump went out and the exhaust had to be replaced to pass inspection (just the muffler). I put in a new pump and decided to install a new fuel filter, new oil fillter, oil (modile 10w40 sys) new air filter, new distridutor cap, arm, plugs new pcv new belt new trans filter and new gear oil in the pig. Now before the fuel pump went out the truck ran fine but, after I installed the new one, the truck started fine went into gear fine, idled fine, but after a mile DOWN the road(the temp gauge started to rise-normal) I would come to a small hill and after I got UP to the top the truck would start jurking and seemed to need some gas so I would slightly push the throttle as I have done for the last 10 years but now it would not thottle up so I had to floor it and with that it would backfire, so now after reaching the top of this small hill, the rest of my drive would go like that, rough idle at the lights and constant jurking and having to floor the pedel with the backfiring. So now I was confused because I did all the tune-up work all at the same time so I went in reverse and reistalled all the parts a replace except the muffler even got new fuel filter, oil filter, oil and while im doing all that I was trolling all the wed sites for answers and the problem with the truck was slowly getting worse to where now it starts with a rough idle right after tuning it over as of now I have installed another Delphi fuel pump(thats the 3rd) a new sending unit, I have rebuilt the tbi with a new fuel pressure regulator, I have checked every vacuum hose, every wire connection, installed all new grounding straps, I have ran codes and disconnected the ECM and drove around long enuff for it to relearn. Twice. In the last month I have read and learned enuff about the chevy 4.3l that I could be a certified technicain myself and its not like I didnt know anything before this, I have worked on vehicles for the last 25 years, rebuilt transmissions, carbs, full resto. This is driving me nuts why cant I find it, the thing thats killing me is that some times the truck starts up fine drives great and then I shut it off to go into a store and then start it up it starts acting up right from the start, rough idle and jurks the whole way back home.I dont have the money to go and buy new sensors so I have`nt tryed the MAP or the TCC ect. And I dont think I need to because like I said some times the truck runs great so that tells me that every thing is in order. Right. At this point a have filed it down to three things, #1 the oil pressure switch, #2 the MAP sensor #3 the injectors because I have noticed there is a drip along with the spray from the nosel, thats one of the reasons why I rebuilt the carb the other reason was I thought the pressure reguletor may have had a hole in it. I have even gone through the valve train and adjusted the rockers. What am I missing? The fuel system is all new except for the injectors and the relay the pressure is 13psi. All the filters on the truck are new all the fluids are new the voltages are in spec the truck shifts fine there are no codes to go on every thing is in order and like I said some times the truck runs like new but for the most part it jurks, the kind of jurking that comes with running out of gas and then it backfires when I step on the gas and it idles rough like its miss firing. Any help would be greatly appreciated

Tuesday, October 6th, 2009 AT 5:09 AM

1 Answer

  • Tiny
  • Munciefan
  • Member

I got it fixed, after I posted this question this morning I when out to the garage and started to work on the truck, to make a long story short after watching the gauges and listening the to engine, I remembered that if you disconnect the fuel pump relay while the engine is running and the engine dies then that means the oil pressure switch is bad, so I went down to Napa and picked up a new switch (pn#op6869) and installed it and now the truck runs like new, problem solved. I dont know how you guys did it but it s fixed. Thanks guys take it easy.

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Tuesday, October 6th, 2009 AT 10:32 PM

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