Cat cut off and straight piped, no oxygen sensor reinstalled, engine will not stay running unless I pump the gas pedal?

Tiny
JOHN BOONE
  • MEMBER
  • 1994 GMC TRUCK
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 306,000 MILES
I had the cat cut off and straight piped, no oxygen sensor reinstalled. No truck will start then shuts off unless you pump the gas pedal. It was running then just shut off, now will start but not run without pumping gas pedal is this because of missing sensor.
Wednesday, February 28th, 2024 AT 2:24 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,477 POSTS
Hi,

The oxygen sensor is used by the powertrain control module to determine the needed air/fuel mixture for the engine. Certainly, they can cause this type of problem.

However, here is what we need to try. See if there are any diagnostic trouble codes stored that may help point us in the right direction. This has an OBD1 system and doesn't require a scanner to retrieve codes. All you need is a short jumper wire or even a paper clip. Follow the directions in this link and let me know what you find:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Also, make sure no vacuum hoses are damaged or disconnected.

Let me know what you find.

Take care,

Joe
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Wednesday, February 28th, 2024 AT 8:06 PM

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