Stalls during idle and loss of power during acceleration

Tiny
ASAND211
  • MEMBER
  • 1995 CHEVROLET S-10
  • 180,000 MILES
I cannot figure out what is going on with this truck. It has a 4.3L engine with "Z" VIN code. I replaced the plugs, fuel filter, distributor cap and rotor, MAP sensor, and IAC valve. None of these things has helped. The TPS seems to be working correctly as I tested it with a volt meter. I replaced the MAP sensor because it was receiving 5 volts but the signal wire showed a voltage of 1.4 volts and did not change with suction. The IAC valve was stuck so I replaced it. The EGR valve tested correctly and wasn't replaced.

When I start the truck(starts easily) it will idle at around 1000-1100 RPM for a about 30 seconds and then drops to about 600 and then to 500 and then stalls. It will staying running if the accelerator is pressed but it is weak during acceleration.

Any help would be appreciated.
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Tuesday, May 7th, 2013 AT 5:23 PM

6 Replies

Tiny
CARADIODOC
  • EXPERT
Start by checking the fuel pressure. If it drops off as the engine speeds drops, suspect a plugged or collapsing pickup screen in the gas tank.
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Tuesday, May 7th, 2013 AT 5:33 PM
Tiny
ASAND211
  • MEMBER
I greatly appreciate the quick response. I have a fuel pressure test gauge but I cannot locate a Schrader valve on the truck. The fuel lines exit the throttle body and proceed down the firewall. Most pictures I've found show a Schrader valve on the top of the engine on the driver's side however the engines are not identical to the one I have.
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Tuesday, May 7th, 2013 AT 6:19 PM
Tiny
CARADIODOC
  • EXPERT
I have the same problem, and I've been running with a pressure gauge attached for over a year. My problem only occurs in warm weather and it just acted up today. You need a full set of adapters so you can find a rubber hose to pull off and insert a "tee". You may also find an aluminum block that screws into the throttle body in place of the supply line, and the supply line screws into that block. Either of those adapters will have the port to connect the gauge. Many auto parts stores rent or borrow tools and they will have the complete set of adapters in the kit.
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Tuesday, May 7th, 2013 AT 6:46 PM
Tiny
ASAND211
  • MEMBER
I have a domestic fuel pressure gauge by Actron and I found the adapter I need on their site so I will try to pick one up tomorrow. I will reply with what I find out in the pressure test. Thanks so much for your time.
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Tuesday, May 7th, 2013 AT 7:14 PM
Tiny
ASAND211
  • MEMBER
No one has the adapter that I need to attach the Actron fuel pressure gauge to the system. Can anyone provide any ideas on how to go about doing this? It seems i'd need to plumb one in with a scrader valve.
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Saturday, May 11th, 2013 AT 4:56 PM
Tiny
CARADIODOC
  • EXPERT
I don't have a test port either. I removed the rubber hose between the engine and fender, then inserted a tee and piece of hose that was part of my kit.
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Sunday, May 12th, 2013 AT 9:33 AM

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