Please help I have been trying to get it running for days!
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 (can't find the right fitting for my guage.)

I sprayed some starting fluid into the throttle body and the engine fired right up. It was a bit rough but at least I know it runs. It died like 10 seconds after running.

I did not check the fuel pressure because I didn't have the right fitting to connect it to.

I replaced the fuel pressure regulator but still no luck.

I don't think it's the timing because the engine doesn't even hiccup or fire at all even for a slit second.

I am starting to believe it is a problem with the injectors but I am confused. Removed one injector from its location and while cranking it doesn't spray fuel. I pulled the old injector spider assembly from the old engine and put it on the new engine (I know the injectors spider works from the old engine.) Still no luck, cranks but does not start. Once again I removed one injector and still does not spray fuel.
Too bad it's not the newer Vortec so I could replace the spider to the updated one, but that's on a side note.

Many people said it is the fuel pressures but the old rod knock engine before this new one ran fine so why wouldn't it run fine now?

I am beginning to thing the ECU is not telling the injectors to fire but I don't know if the electronics are designed that way. I want to replace the camshaft sensor see if that fixes the problem and knock sensors and figure out their actual positions. Also I cannot find a crankshaft position sensor in this 1993 Vortec. I am not sure if they actually had one.


What I plan on doing later:

1. Checking timing with a timing light
2. Checking actual fuel pressure numbers and see if it drops when I stop cranking
3. 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.

 

How much gas do you have in there?

I know it shouldn't matter, but... What I think of is that, with some cars, you have to seem to had a certain amount of gas before it will fire and run right again.

May not be your problem, but, just a thought.

And is your fuel pump priming?

(I just made the transition from a trouble-ridden 1993 - that I kinda should have never bought, but the wheels it had were of great sentimental value to me, and still are - to a PERFECT-running 1994, with the dumb issue of power windows not working at all, and a blinker. And the non-digital dash I could technically change to digital, and probably will. Beyond that... I'm happy to Pay It Forward, any way I can, and am willing to share any and everything I know and have experienced about our trucks.)

 

I have a little under half a tank of gas in the tank.

I tried fuel pump priming, but still the same situation. Many people said that it might be low fuel pressures but the old engine that was in it before, ran perfectly fine (except the rod knock.)

 

The thing is... That it ran perfect for that brief time with the starting fluid in the intake, really points to SOMETHING fuel.

It wouldn't have did that if there was no spark, or timing issue..

And, obviously, you have air, compression/timing, and spark. (Can't start an engine with no air, such as like a closed throttle plate. Will flood.)

 

I'm beginning to think it's a computer thing possibly a sensor or the ECU is not firing the injectors or something. I just don't know how to diagnose that. I will check fuses tomorrow and cam sensor. Still can't find if the engine has a crankshaft position sensor.

 

We need to know the fuel pressure and leak down at the port at the back of the intake.
Rent a fuel pressure tester from a parts store if yours does not have the right fitting.
key on engine off the fuel pressure should be at least 60-62 psi and should not drop below 55 psi in 5 minutes.

Do this and report back with your results so we can further assist you.

 

I just thought of this. The cam position sensor is in the distributor cap. I don't think the cam position sensor is bad because I am getting spark. Doesn't the cam position sensor tell the ignition module to spark at a certain point?

 

Alright I will do it tomorrow and report back tomorrow with my results, thanks!

 

I measured the fuel pressure with a gauge I rented from O'Reilly. The pressure while cranking is at 55PSI and then stays there. I bought a Hanes manual and checked the spark plug wires again and I found the simple problem. While I was connecting the spark plug wires I was going off a picture I found on the internet. That picture was wrong and I followed the Hanes manual. I also figured out that the throttle position sensor is bad and that is why it wouldn't fire. Now it works fine and starts fine!!!

So my problem was:
1. Throttle Position Sensor was bad
2. Spark Plug wires were in the wrong position
3. Fuel pressures seem fine but I guess they are low

Thank you for all the help guys. Will update if something changes or it doesn't start again.

 

Glad you got it figured out.

Word of advice next time when checking fuel pressure. Do not test the fuel pressure while cranking.

Test it, key in the on position, engine off. It will prime the pump and get it up to pressure. Check that initial pressure and it should be 60-62 +/- a couple PSI and should remain at or above 55psi for 5 minutes