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Jerry Newton
Jerry Newton, GMC Technician
Category: GM
Satisfied Customers: 4413
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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2003 ZR2 S10 4.3L won't rev past 3500 absolute tops. Has

Customer Question

2003 ZR2 S10 4.3L won't rev past 3500 absolute tops. Has next to no power seems like the trans is slipping from first into second
Submitted: 1 year ago.
Category: GM
Expert:  Jerry Newton replied 1 year ago.

Two things to check right off the bat: fuel pressure, use a gauge (borrow for free from Autozone, etc). Fuel pressure must be 55psi or higher at all times, test it while driving and getting the truck to act up. Next, exhaust back pressure, use a gauge (same deal, borrow for free), remove the front oxygen sensor from one side of the engine, and attach the gauge. Drive truck and make it act up, exhaust back pressure should not exceed 1 psi. If it does, you have a catalytic converter that needs to be replaced.

I would do these two things first, before anything else.

Customer: replied 1 year ago.
No Cat
Pressure between 58 & 62 PSI
Expert:  Jerry Newton replied 1 year ago.

Pressure stays that high while driving it?

Expert:  Jerry Newton replied 1 year ago.

I'm sorry, I'm going to have to opt out of this question, due to the fact that I am going to be away from my desk for several days.