Truck won't start

My 2002 GMC Sonoma truck won’t start. The dealer replaced two oxygen sensors, the mass air sensor, and the spark plugs. It worked for about a week, then same problem. The engine turns over but doesn’t fire. It doesn’t seem to matter if it’s cold or warmed up. There are no codes in the check engine system, and the light doesn’t come on. The dealer is stumped. Maybe one of you has a suggestion.

I have worked at 6 different Dealers and a “crank no start” has never remained a “crank no start for long”. Negoiate getting your money back for the unneeded work and move on.

Did they check for a defective crankshaft position sensor?


A defective camshaft position sensor is on their list of maybes. They tell me that when one of these goes bad, the truck often just quits, and since it has never quit on me (just refuses to start), they are skeptical. The other item on their list is the injector bank, which they say is very expensive to replace. The last time it wouldn’t start, they cleaned out the new fuel distribution valve and it started. Started a few more times, then same no start problem. They checked with GM and there doesn’t seem to be similar problems with other GMC Sonomas of this year. Earlier models had problems with the camshaft position sensor. They are still stumped. I appreciate your good advice!

Tester mentioned a crankshaft position sensor you responded with a comment about a camshaft position sensor.

I did read about some GM engines (the example was the 3.8) whose camshaft position sensor must be positioned correctly,didn’t say what happens when not.

As we have noted in other threads, if the camshaft position sensor fails while a engine is running a default program takes over. After the engine is shut down this failure may prevent re-start.

The shop has no clue. They did not check fuel pump pressure, fuel filter or the fuel line. If you have driven through deep water, there could be moisture in ignition system components. They should not have changed the oxygen sensors. Either they are as bad as you say or you are holding back information. If the computer isn’t giving codes, it may be out to lunch.

Well, they did test the fuel pump pressure, and the injectors and the crankshaft position sensor. They couldn’t find anything not functioning properly. But they replaced the crankshaft position sensor and the problem seems to have disappeared. Thank you Tester for the tip!