Ok strange story had to charge battery because door doesn't shut tight on my 1997 blazer and I left it sit over holiday. So I put truck on trickle charge after hour attempted to start. A burst of flame with loud noise came out of engine and noise and flame were out like poof. Looked on firewall for anything burnt or smoke or any smell of oil or electric nothing attempted to start again no flame but engine revs up to three thousand rpms and cuts out. She is paid for and I love my truck any ideas where to start looking for the issue fuel pump was replaced a year ago

 

Usually when a motor back fires,the timeing is off.Sometimes the distributor loosen`s up and move`s about.There`s only one setting for the 4.3 vortec.So you really can`t adjust the timeing on them.If the distributor is the original one that came with the blazer?Possibilty the distributor has failed.Most of the distributors that came with the 2nd generation S10`s/Blazer`s where made out of plastic.If you don`t know how check out the distributor yourself?Take it to your mechanic.Have him check it out for you.If the distributor has failed?Your gonna have to replace it with a new one.If you have the extra funds to buy a(real) distributor go for it.But if you don`t, just replace the same type you have.

 

A backfire, regardless of the cause, can result in failure of the plastic upper intake plenum. The fact that the truck spikes to 3000RPM may indicate that there is an issue with intake manifold sealing that needs to be addressed. Also, everything between the airbox and the throttle body needs to be sealed up tight as well or the PCM will not see the proper airflow through the MAF sensor and the engine will not run properly. Disconnecting the MAF sensor should allow the engine to run properly if there is a large leak (or if you wanted to try to run the engine without the intake piping on the throttle body - say to check for vacuum leaks in the upper plenum).

As far as the cause of the backfire, that can be a number of things as well. Stretched timing chain, improperly timed and/or worn distributor, sticking valve, etc. Even excess fuel in the intake manifold via a leak in the spider, lines, fpr, etc can lead to a backfire. Issues with the fuel system in these trucks are quite common so that might be a good place to start looking.

The distributor being made of plastic isn't a real cause for concern in my opinion, you just need to be careful when tightening the cap screws. Many of the stock distributors have gone for hundreds of thousands of miles without issue. There are aftermarket distributors (Skip White) that have an aluminum base that aren't any more expensive than a stock style one if you need extra peace of mind.

With any distributor, the life expectancy of the distributor is tightly tied to the "Camshaft Retard" value. If the value is not set to zero through proper installation & adjustment of the distributor, then the gear mesh between the camshaft gear and the distributor gear could cause excessive wear.

Let us know if/when you have any further questions! There are those of us here that can help without pushing you to a mechanic!

 

Thank you so much I have talked to several shops only to get the run around am starting with the distributor and will keep y'all posted

 

LMAO..This should be good. Why should he use aftermarket instead of G.M.?

 

If you were bothered to actually read AND comprehend my post, I never suggested aftermarket over GM. I stated that the stock plastic distributor design takes the majority of these trucks to well over 100k miles without issue and can easily last the life of the engine with proper installation. I gave a link to an aftermarket distributor for those that prefer a metal housing.