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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4591
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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P1093 vin 5F829570 Looses power in a surge kind of way.

Customer Question

vin 5F829570
Looses power in a surge kind of way. Stalled completely a few days ago with no restart but now that its cold and I reset CEL it starts and makes power but it hesitates around quarter throttle almost every time. Fuel filter has 89% life left. Blows white/blue smoke when hesitating and smells of raw fuel. I have some data logging which shows between 35000kpa and 66812kpa from closed throttle to .75+ throttle under load. FP around 2280kpa engine off. Problem seems to have reduced to almost nothing in the time that I was data logging. Now for some reason Fuel rail pressure is not showing up on my data logger so cant test anymore.
Submitted: 1 year ago.
Category: Chevy
Expert:  Jerry Newton replied 1 year ago.

There are cases, and there is also a bulletin that talks about it, where the rubber fuel line going to the engine is collapsing, which restricts the fuel flow and can result in this issue. Replacement of the rubber fuel line is acceptable and recommended, I'll attach the TSB so you can see what it entails.

Also, replace the fuel filter anyway. Use AC Delco, and buy it from the dealer. There was a huge issue with defective fuel filters, some counterfeit filters got labeled as AC Delco and were causing this issue. Those counterfeits have been identified and removed from dealer stock, but I would replace yours anyway because we just don't know what the quality of that filter is. I've personally had to replace several counterfeit filters that were causing this issue.

Customer: replied 1 year ago.
Replaced filter. No change.
Replaced hose sections on fuel line. No Change.
Performed 'Bottle test' for FPRV leakage. Results negative. No progress from any of these.
Any other ideas?
Expert:  Jerry Newton replied 1 year ago.

Perform these tests, there seems to be a restriction on the inlet side of the fuel system.

1. Install a vacuum gauge at the fuel service port by the alternator.

2. Run the engine under the following conditions and check the vacuum gauge.
• Cranking - 3 inches to 4 inches HG of vacuum.
• Wide Open Throttle (WOT) in park or neutral - 4 inches to 5 inches HG of vacuum.
• Hard Acceleration driving - 8 inches to 12 inches HG of vacuum.

3. If the vacuum is too high, check for a restriction such as a restricted fuel filter or kinked fuel line.

4. Run a fuel hose into a separate container at different locations on the low (suction) side of the fuel pump.

5. If the vacuum is low, check for air in the system. Install a clear hose or run the suction hose into a separate container to isolate the source of the air.

6. If the vacuum tests OK, check for fuel return from the fuel pressure relief valve mounted in the rear of the driver side common rail during the lack of power mode.

7. Check the fuel return rate of the fuel injectors.

This basically comes down to a fuel line restriction, a clogged filter, a faulty pressure regulator, injector(s), or injection pump. The vacuum testing will turn up a restriction in the fuel system, you've apparently already done the testing for the pressure regulator, so we are narrowing it down.