My son's 2003 Chevy S10 ZR2 has an intermittent starting problem. Cranks well and the battery and charging system checked out OK. Acts like fuel supply is shut off. We suspected the antitheft system but can, t prove it. Often it will eventually start and run fine after that. Seems to happen about twice per week with no consistent pattern. It recently had the radio/CD player replaced by techs at Best Buy. I checked with them and they think its unlikely to have caused this. OBDscan shows no codes other than an evap canister issue. Truck has about 90,000 mi on it. If the antitheft system has anything to do with this, I sure would like to disable it. Thanks for any insight you may have.
You can't disable the theft deterrent. You would have a seccurity light on or flashing if that were the problem and it would be starting and stalling.
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.