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1997 gmc 1500 4x4 has a engine surge or chug at high speed ...

Sent to Car Experts September 23 10:23 PM

1997 gmc 1500 4x4 has a engine surge or chug at high speed over 50 mphs

 

Optional Information:
1997 GMC 1500 5.7 vortec

Already Tried:
tuned up new plugs,cap,rotor new wires new o2 sensors, new fuel filter, injsctors cleaned and engine scan, no codes present.

Customer (name blocked for privacy)
Status:  Closed   Value: $15
Answer
September 24 2:53 AM (4 hours and 29 minutes and 56 seconds later)
         
REPLIEDCheck Mark
The first thing that needs to be checked would be the fuel pressure. If it is not within specs it will cause this type of problem. Do you have access to a fuel pressure gauge? Also you can check the Mass Air Flow sensor. It is located in the air induction tubing in between the air filter and the engine. Pull it of and clean the inside of it out with throttle body cleaner. Be careful not to damage the grid inside. Let me know what you find.
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BOBBY -- Technician/ Service Advisor -- 100% Positive Feedback on 1120 Car Accepts
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Reply
September 24 12:34 PM (9 hours and 40 minutes and 38 seconds later)
         
Reply to BOBBY's Post: yes fuel pressure is good and the mas air flow sensor has been cleaned.
i acts like a ing cut off not fuel related.
Customer (name blocked for privacy)
Answer
September 25 1:21 AM (12 hours and 47 minutes and 8 seconds later)
         
REPLIEDCheck Mark
Can you tell me what your fuel pressure was? Also GM does have a technical service bulletin for this truck with your symptoms. It requires the computer being recalibrated to newer specs. But for now get back to me and let me know about the fuel pressure and what conditions it was checked under.
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BOBBY -- Technician/ Service Advisor -- 100% Positive Feedback on 1120 Car Accepts
ASE MASTER CERTIFIED, CALIFORNIA EPA AIR CONDITIONING CERTIFIED, AA DEGREE AUTOMOTIVE/DIESEL TECH
Reply
September 29 10:57 PM (4 days and 21 hours later)
         
Reply to BOBBY's Post: 56 p[si at start up and droped to 53 psi running at idle
Customer (name blocked for privacy)
Answer
September 30 9:46 AM (10 hours and 49 minutes and 22 seconds later)
         
ACCEPTEDCheck Mark
That pressure is low. The pressure specs on your vehicle are between 60-62 psi. What does it go to if you give it gas?
Picture
BOBBY -- Technician/ Service Advisor -- 100% Positive Feedback on 1120 Car Accepts
ASE MASTER CERTIFIED, CALIFORNIA EPA AIR CONDITIONING CERTIFIED, AA DEGREE AUTOMOTIVE/DIESEL TECH
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