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Chevy 350 engine problems

Tiny
GONE
  • MEMBER
  • 1935 CHEVROLET TRUCK
I have a 94 4x4 1500. 190000 miles 12000 miles on a short block. The engine idle is not as smooth as it could be and while sitting in neutral reving the engine it shows no sign of problems. While driving the truck it fires back thru the intake then continues under steady driving to pop thru the intake. I have checked for leaks around the intake and all hoses. Have installed new plugs, cap and rotor. No codes show. Have capped off the egr valve to see if it was leaking. Left the control connected for the egr. The timing ihas been moved back and forth and still no change. Watched the injectors at idle, they have a fine mist. Snap the fuel open and the mist turns to a heavy spray. Have not checked fuel pressure for an adapter has to be made for this model.
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Sunday, November 25th, 2007 AT 6:06 PM

8 Replies

Tiny
RASMATAZ
  • MECHANIC
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Inspect and test the idle air control valve and the throttle position sensor. And also follow up with the fuel pressure.
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Sunday, November 25th, 2007 AT 6:24 PM
Tiny
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The truck was purchased 8 months ago and ran fine until a month ago. The head work is unknown because it was done before we bought. We received paperwork showing the block being bought at a major parts store.
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Monday, November 26th, 2007 AT 5:44 PM
Tiny
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Additional probable causes:

Sparkplugs of wrong heat range
Ignition timing off
Excessively rich or lean A/F mixture
Vacuum leak

Check the fuel pressure
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Monday, November 26th, 2007 AT 6:35 PM
Tiny
BMRFIXIT
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As stated above check the TPS and have the fuel pressure tested
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Monday, November 26th, 2007 AT 7:20 PM
Tiny
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Hook up a vacuum gauge to an intake manifold vacuum-meaning full vacuum not ported/venturi and tell me where that needle is and what its doing
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Monday, November 26th, 2007 AT 9:50 PM
Tiny
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Checked vacuum and at idle it is 21 inches and when the engine would have the rough moment of idle the vacuum would go to 20 and a couple of times 19. Except for those hicups it was steady at 21. Have just now got set up to check fuel pressure will do that tomorrow.
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Friday, November 30th, 2007 AT 7:19 PM
Tiny
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Checked fuel pressure to be 10 pounds opened throttle pressure droped to 9.5 and returned to 10. Checked plugs they are mid heat range. Still unable to find disconnect to disable the advance. Not on firewall, not behind TB.
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Saturday, December 1st, 2007 AT 11:57 AM
Tiny
BMRFIXIT
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.
.

I was reading it over and I notice you listed what was changed on the truck but no mention of ignition wires have you checked them
Also check with volts meter the TPS volts as you pushing down on the paddle
And also as you release slowly you are looking for steady volts up or when releasing down
Good luck
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Saturday, December 1st, 2007 AT 6:35 PM

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