Hi there, I am new to the forum. It just happens the afternoon after I find this sight, my Blazer dided on me. I need some help, I am running out of ideas to check. Here are the simptoms.

The motor turns over, intermintant back fireing through the throttle body, will not start
While the motor is turning over the check engine light stays on.
The Blazer ran fine 6 hours previous.

Here is what I have checked / replaced.
I have 12 volts to the coil and control module replaced control module
fuel pump is running, cannot check the fuel pressure, I do not have the right fittings for my Gauge
I have spark, checked by a dummy load
Checked throttle position sensor's resistance, with in operating specs
Checked Primary / secondary sides of the coil, same.

I am very confused by this problem since I have fuel and spark. It acts like the timing is very retarded, almost 180 degrees off.

Any sujestions / theroies would be appericated. and if anyone has some good scematics that would help too, the manual I have is lack luster but it is all I could get ahold of on short notice.

Thanks
Paul

 

From what I have read on here, the fuel pump can be a big issue. Even if you think you are getting fuel, you may not be getting enough fuel pressure. IIRC it needs to be at 66psi at idle.

Search this site, there is a ton of good information.

 

Do you have a scanner if so check codes and tell us what you get...we can go from there...

 

Here is alittle more info I forgot to put in here when I was on earlier

2000 Blazer 2wd Automatic, the engine is a 4.3L with the Central Fuel injection (weirdest setup I have ever seen)

Thanks

 

Unfornatuly I do not havea scanner, I don't exactly have the coin to spend on one. and I cannot get the Blazer to one of the local autoparts stores that offer a free scan.If someone knows of a store in the Grand Rapids MI area that has one on a rental or loan-a-tool program, let me know... It would be a huge help...

 

To check the Fuel pressure you usually hook a gauge directly up to the fuel rail via a schrader valve.

 

try this: find the timing mark on the crank if there is one, get it to 0* or TDC...remove the distributor cap and check rotor direction...it is possible that the timing is not where it is supposed to be...although this is a long shot I just remembered about a problem I had tuning up a 65 Olds Cutlass. Engine backfired once and the timing chain skipped a tooth... back then they had nylon teeth...but not sure about here. Have you checked the cap and rotor??? I have read on here that sometimes the rotor button will fall out of the cap...maybe time for a tune up....

 

ok, you've checked for and have spark.
Maybe pull a spark plug and see if it's fuel fouled. Backfiring thru thr T/body (to me) indicates either over fueling or a timing problem.
I would lean toward over fueling.
Without having a code, it's pretty hard to guess.

 

Can still get an idea on the Pressure (yes a gage is the best way to test) but can see if you lightly press. Trickle not enough pressure, shoots to the hood enoughmaybe. But only way to be sure is to use the gage.

Do you have gas showing up in the air cleaner or tube to air cleaner? Or is it just Popping like pre ign. threw the TB?
Have you checked your crank sensor?

 

It is just poping like Pre Ignition.
I have not checked the Crank Sensor Yet, my manual dose not give any values for it. Dose anyone have the specs?