2004 GMC Sierra
Mileage
129,341
Service Date
11/26/2025
Services Performed
- Vehicle came in- Towed in, would not stay running. Brought into shop and had a strong fuel smell. Checked for external fuel leaks and could not find any. Hooked pressure gauge to check fuel rail pressure to find it started at 58PSI and would drop off, which meant system would not hold pressure. Went through and did a pressure drop off test for fuel injectors. Cylinder 7 and 8 injectors failed. Went through and checked misfires and found it would misfire only on 7 & 8 which lines up with fuel injector test. Replaced fuel injectors to find that truck will run but still has a misfire. Went through and inspected/changed plugs, wires, and coils off the misfiring cylinders and found that misfire did not move from those cylinders (7&8). Noid tested and checked for injector pulse on those cylinders to verify injectors are good after replacing. Found good pulse. Confirmed spark on 7&8 with spark tester. Removed valve cover on passenger side bank to inspect rockers, valve springs and rocker rail.. Found that all looked good. Proceeded to go into a compression test to test cylinders. Tested cylinder 8 and received the following reading.. Barely 50PSI. Tested cylinder next to it. Cylinder 6 .. reading there was 105PSI. During testing and inspections, a message would come up on dash saying engine coolant over temp. coolant temp would fluctuate/spike from half way in gauge to almost fully hot, and the immediately drop back down to half. Suspected either a faulty coolant temp sensor or sticking thermostat due to the fact that truck sat for a period of time.
- Replaced Injectors 7&8- Truck would not stay running on its own without replacing injectors.. needed to replace to see what other issues arise.
- LOF
Alvin N. gave our service a 5 star review on 11/27/2025
