99 S-10 Pickup won't start

4.3 liter engine, auto trans. Vehicle started fine the night before last after I started it to make sure the heater core bypass hose job I had done was leak-free. Ran like a dream at that time. Now suddenly it won't start. It cranks 5 or 6 times, then has kind of a laggy crank, and then repeats the process. It's not the fuel pump, that has been newly replaced. It's been a while since a tuneup and we were planning on having that done soon but still I have no idea why the sudden refusal to start. Any input would be appreciated, we have only this weekend to solve this problem before we both go back to work and we need both cars. :banghead:

Wow, that is EXACTLY the same problem I posted just a couple posts before yours. I am going to try the battery thing they recommended and see what happens.

Yeah, i saw that. But the battery thing did squat all for me. :banghead:

Make sure the battery is up good.
Does it crank over good?
If not charge or jump battery.

Make sure battery and charging system is good.


Even if the fuel pump is new always check the fuel pressure.
What kind/brand of fuel pump did you feed it?

What engine?

Wow, that is the EXACT probglem I posted 2 posts before yours. I just put the battery on the charger even though it seems fine and see what happens. I will keep my post updated. Please do the same if you find something out.

We actually got a new battery not too long ago. It seems to crank just fine, it's almost like it just doesn't want to catch the spark. Have had occassional issues in the past with hard starts too, if that makes a difference. I don't recall the brand of the fuel pump to be honest, my mechanic replaced it several months ago sometime in the summer. (We didn't tend to drive this truck too much till recently.) We can hear the fuel pump kick on just fine though and there was strong smell of fuel when frustrated hubby pumped the gas (to the non-carburatored engine) and tried to flood it. I believe it's the X engine.

Wet (fuel soaked) plugs will shunt all spark energy to ground through the ceramic insulator. Make sure the plugs are clean, properly gapped, and dry. Remove a couple of the more easily accessible plugs and check their condition. If the plugs are fuel soaked, replace them. Flooding can be a sign of a leaking fuel line or stuck injector.

Distributor caps on these engines are prone to insulation breakdown between terminals, and the resultant crossfire will prevent starting. This is frequently accompanied by backfire or afterfire. If this is not apparent in your case, verify good spark energy to the plugs. An inline spark tester is very helpful for this, but testing with a manual gap or spare spark plug can be just as effective.

Once you have verified the ignition system is sound and the plugs are in good condition, you can manually administer some fuel through the throttle body to see if the engine will fire.

If all things are normal, there may be a timing issue caused by either a crank or cam position sensor, timing chain problem, or ICM problem. Again, incorrect timing is often indicated by backfire and/or afterfire. Either of those would be good clues.

the 96 and Vortecs you do not set the timing,using a scan tool only to set the distribitor which has to be 0 degrees for the cam sensor retard.Most have the 8th vin "W" vortec 4.3 and I never seen one with the "X" engine yet

Just in case you don't read my thread, I got the Blazer started. I put a hair dryer on high and pointed it on the top of the distributor. Let it sit there for about an hour and it started right up. I'll bet it would work for you to since you have the exact same problem. Good luck.