My son has a 1994 Chevy S10 Blazer that won't stay running. Last week when he came home, the key wouldn't turn off. We finally had to disconnect the battery. We have since had the ignition switch replaced BUT since then, it won't stay running. He will drive about a block and then it dies. We are stumped at what could be causing this. Over the past year, we have replaced everything except the engine itself...any ideas? Grateful for any input.

 

What have you checked so far? Have you verified good, hot, blue spark? Have you checked fuel pressure? Have you checked your fuel pump relay? Are there any stored fault codes? Is it throttle body or central port injection? Give us some more information and we should be able to help you out.

 

Without sounding like an idiot...are those all things that will have to be checked by a mechanic? How would I know about the fault codes? We had a mechanic replace the ignition switch so I assumed he would've taken care of any codes, etc. Unfortunately, when we bought this, it came without a manual so we have no resources to go by. I will see what I can find out...thanks for a starting point.

 

The mechanic may or may not have checked the various things I mentioned. Usually mechanics stay pretty focused on the specific trouble area. If the truck wasn't turning off then the mechanic probably checked the ignition system and if he found a fault in that system then he probably didn't look any further.

To solve the problem you're having will take some specific troubleshooting. You'll have to test various systems in the truck to find where the problem is. It could be fuel-, spark-, or security-related. It could even be somewhere else in the truck and what you're experiencing is a secondary system.

The first question is whether or not the "Check Engine" light is on. If it's on then there's a trouble code stored. Check the trouble code and post the code back here on this thread. Search around on the Blazer Forum for instructions on how to retrieve the codes.

The next question is about spark. Verify spark at each spark plug. It should be hot and blue. If it's orange then it's not very powerful. You can get a spark tester to do the test or, if you're brave, you can hold the spark plug against the engine block and watch the spark jump across the gap on the electrode.

After spark, verify fuel pressure. On these Vortec trucks the fuel pressure should be at least 60psi and hold for ten minutes without dropping more than 5psi. You'll need a fuel pressure gauge to do the test. You can borrow one from many chain auto parts stores with a small deposit. Instructions for a fuel pressure and leakdown test can be found here on the Forum.

Once you've check all of those things post here again and we'll go from there.

 

Found out there was a wire that disconnected...I want to say it was the O2?) wire. Sorry, I don't remember. Once it got connected, it is running fine. I was pretty sure it was something simple, but just didn't know where to start. Thank you for all your help! This is a great forum.

 

You're welcome. I've learned a heckuva lot about these trucks from the Forum. I'm glad I was able to help you out some.