I just swapped in a 4.3 Vortec engine with less miles into my 1993 Chevy S10 Blazer 4x4. The old engine failed due to lack of lubrication because the previous owner didn't notice the oil lines leaking. Today I finished putting everything back together and tried to fire it up. It cranks but doesn't fire.

I already checked for spark from the ignition coil and it's there. The fuel pressure seems to be there when I release the small purge valve on the fuel line near the intake. I can also hear the fuel pump. I have not checked pressures though. I have connected all the sensors so I doubt it's that.

Tomorrow I will check:

1. Timing with a timing light
2. Actual fuel pressure numbers and see if it drops when I stop cranking
3. Possibly remove the intake and check if the injectors are firing
4. Spray starting fluid and see if the engine would start
5. Replace entire distributor with the one from the old engine (see if the engine fires)


If anybody has some insight to what may be the problem, please comment. I thank you in advanced for all comments and I really appreciate the help. I will post back with my results tomorrow.

 

easiest things first.
spray some starting fluid in the throttle body. If it fires, its a fuel delivery issue. Also check for spark at the Spark plug wires

 

We need more info. What year is the new engine? What type of injection system does each engine have, (TBI, CMFI, CSFI)? What type of ignition system on each engine, HEI or EDI? Does the new engine have a crankshaft position sensor mounted in the timing cover?

 

Sounds like you may have a defective ECM(Engine control module)This is the brain of the motor.This goes out you will have the same effect you have now.Motor turns over but no start.I had an 81 chevy malibu that had the same problem.Sometimes they would go out while driving.So if you can afford a new one..Go ahead and replace it.Don`t buy that cheap crap fromG.M..These parts are made to fail.Look up Summit Racing.com They have lots of choices to choice from.