6.0 Wont Start

**skeene** · 04-11-2020, 11:46 AM

Hey I have a 2003 chevy Silverado with a 6.0 in it. Im having issues im needing some help with I cant figure it out. It sat up for a few months, It cranked right up and ran very rough, spitting and sputtering, I only cranked it to move it. Then a few months later I go to crank it again and it would turn over but wouldn't even try to fire off. So I drained all the fuel, changed the fuel filter and put fresh fuel in it. It still would only turn over and not even try to start. So then I checked the fuel psi, it was a steady 58psi. I changed the crank sensor and the camshaft sensor, I had a nelson tuned computer in it, and I put the factory computer back in it, nothing same thing. I then put the Nelson tune pcm back in it. Now as soon as it starts turning over it backfires out the exhaust extremely loud one time then continues turning over without starting. No codes. Took the valve covers off, all looks good, checked fuses and the coils and harness all looks good. Anyone got any suggestions??

Thanks,

***SMWS6TA*** · 04-12-2020, 07:57 AM

Check the injectors?

**skeene** · 04-12-2020, 03:03 PM

No I havnt. Im really not sure how to.

***SMWS6TA*** · 04-13-2020, 06:19 AM

You will need to have them flow tested. Check your local area to see if any places near by. I went to a boat engine repair shop to have mine done.

There are a few places online that offer the services but they can be expensive. Not as expensive as a new set. I paid $25 per injector to have them flow tested and repaired if needed, meaning new seals put in.

**pajeff02** · 04-18-2020, 04:42 AM

No codes at all? That seems very odd. Backfire is definitely a timing or lean fueling issue - how many miles on it? Any recent work been done on it prior to the issue developing?

**deeze12** · 09-22-2021, 10:14 PM

Originally Posted by skeene

Hey I have a 2003 chevy Silverado with a 6.0 in it. I'm having issues I'm needing some help with I can't figure it out. It sat up for a few months, It cranked right up and ran very rough, spitting and sputtering, I only cranked it to move it. Then a few months later I go to crank it again and it would turn over but wouldn't even try to fire off. So I drained all the fuel, changed the fuel filter, and put fresh fuel in it. It still would only turn over and not even try to start. So then I checked the fuel psi, it was a steady 58psi. I changed the crank sensor and the camshaft sensor, I had a nelson tuned computer in it, and I put the factory computer back in it, nothing the same thing. I then put the Nelson tune pcm back in it. Now as soon as it starts turning over it backfires out the exhaust extremely loud one time then continues turning over without starting. No codes. Took the valve covers off, all looks good, checked fuses, and the coils and harness all look good. Anyone got any suggestions??

Thanks,

When your vehicle backfires there are several things that can be wrong:
cold starting fuel pump, fuel senders, spark plugs/ and or wires, fuel filter clogged, exhaust muffler, mass airflow sensor, engine cooling system, and ignition coil.

If the engine runs rough, then this usually points to spark plugs and wires, a faulty fuel pump, or a clogged fuel filter. If it backfires when cold, then it's the Mass airflow sensor.

OE p/n 41-962 AcDelco and OE cost is $11.02 per, book time is 1.1, wires OE p/n is either w delphi coils 19417606 and costs OE $121.50, or w/o coils 748HH ACDelco OE cost $141.81 and since you would be replacing the spark plugs, there wouldn't be any extra labor cost as this is in the same component area fixing the same issue.

MASS airflow sensor OE p/n is 19330121 and OE cost is $350.54, and book time shows 0.7 to replace.

Hope this helps.