my 2000 blazer with a 4.3 suddenly just stopped running a few weeks ago. it wasnt throwing any codes up until yesterday. it just spins when you turn it over and it will eventually start but only idle at 500-1000 rpms and if u try to give it gas it will bog down and die. Yesterdat i fianlly got a CEL for map sensor and multiple cylinder misfire. I changed the coil before this on a guess and the fuel filter but still nothing. Does this sound like a common map sensor malfunction?

 

Part 1 -MAP Sensor Test (P0106, P0107, P0108). GM 4.3L, 5.0L, 5.7L

check fuel pressure and make sure pressure holds.
https://blazerforum.com/forum/tech-a...agnosis-23038/

 

map and misfire will usually happen when you have rough running issues. It doesnt mean its bad,its just not operating correctly do to another problem. I bet its your fuel pump. Usually nothing is thrown if its the pump,and these blazers seem to eat em like candy. Rent you a fuel gauge at autozone. (free loaner program,just leave retail deposit which is refundable later) check your pressure and see what it is. It needs to bump up to at least 60 psi when you turn the key,and hold above 55 after 10 min. if it doesnt hit 60(even 55 is too low at key on) then its your pump. Make sure you stick with oem on this part,some aftermarket stuff is ok,but pumps is definitely a oem deal.Trust me.


edit : darn burned you beat me to it. I need to type faster.lol

 

thanks for the replies guys. ill pick up a rental feul pressure gauge tomorrow on my way home from work. ill post up results.

 

ok so today i did a fuel pressure test and the result are... with the key turned to the on position it shot up to 65psi and then fell slowly down to about 54. now with the engine running it was a constant 60. good results?

 

anybody?

 

seriously.. nobody?

 

seems like good pressure to me. Pull the connector on the MAF and see if it starts. If it's doin the same thing start sprayin starting fluid into the intake and see if it starts easily. If it's still doin the same thing pull the spark plugs and check condition, do compression tests on all the cylinders and post up the results if you get this far. If the compression is good you'll need to check the new coil for proper resistance values then doing spark checks at the plug wire boots. GL!

 

When was the distributor cap & rotor replaced last? Use AC Delco only.

 

yes the cap and rotor was replaced about 2 years ago. From trying to start the truck so much and sitting the battery died, hence it cleared the codes. Was messing around with it again today and from trying to start it so much the CEL came back on with p0102 which is maf/vaf ckt low. Now is this probably because it barely will even fire, let alone idle for more than 5 seconds? Also the only way to get it to fire is to hold the throttle wide open.