95 blazer Stalled and wont start

got on the interstate to work this morning.. and couldn't get up to speed.. about 40 mph.. and after I hit that speed any attempt at acceleration made my rpm DROP way low.. to the almost stall point.

I drove on shoulder about a mile to next exit.. and there is an Autozone there. I pull over and have them check my computer.... I've got a P0134 and P0131 code showing up.. and the guy there says my upstream O2 sensor is disconnected or dead.

ok.. i think... I'll continue slowly to work and fix it when I get home this evening... well.. that plan works out for all of two blocks.. and I stall.

I pull over to a parking lot.. and now it will not start.. Kinda acts like it wants to start but never turns over on it's own.. for even a second.

so.. my questions are... Could a bad O2 sensor cause that?
and where are the 02 sensors located? I only know of the one that is under the passenger seat on the exhaust pipe.

Thanks...

I think that when I first got the truck in 97 (used) about 6 months into ownership i had same problem (wouldn't start).. and took it to dealership and they said it was 02 sensor and charged me $400 for analysis, parts, and repair. So I just wonder if it could be same thing again. if so I'd want to do it myself.

:banghead: :banghead: :banghead: :banghead:

Could a bad O2 sensor cause that?


No, I don't think so. While your first symptom (gassing at 40mph causing a stall) doesn't match what I'm about to describe, you'll want to check your fuel pressure anyway. There's a shrader valve on the inlet fuel rail that connects to the back of your intake manifold; check the pressure there. If it's not between 60-65 try replacing your fuel filter.

You'll also want to see if you're one of the many '95 owners that has a faulty fuel pressure regulator. To check, remove the vortec nameplate from the top of the upper intake plenum, take out your IMTV and look in to the intake. A properly working injection system will be indicated by a grimy carbony blackness inside the entire manifold. A faulty injection system will be indicated by clean or golden spots, and puddles of fuel. If the passenger side is washed you probably have a leaking fuel pressure regulator. If the drivers is washed you probably have a leaking nut kit. You'll want to replace both if either is not working properly.

If this has been going on for long you'll want to clean your EGR and install a new gasket while doing this job. Leaking fuel can also harm your cat, so you might have to look at that in the future too.

If fuel pressure is good, and you don't have a leaking regulator check spark.

Good luck.

No, I don't think so. While your first symptom (gassing at 40mph causing a stall) doesn't match what I'm about to describe, you'll want to check your fuel pressure anyway. There's a shrader valve on the inlet fuel rail that connects to the back of your intake manifold; check the pressure there. If it's not between 60-65 try replacing your fuel filter.

You'll also want to see if you're one of the many '95 owners that has a faulty fuel pressure regulator. To check, remove the vortec nameplate from the top of the upper intake plenum, take out your IMTV and look in to the intake. A properly working injection system will be indicated by a grimy carbony blackness inside the entire manifold. A faulty injection system will be indicated by clean or golden spots, and puddles of fuel. If the passenger side is washed you probably have a leaking fuel pressure regulator. If the drivers is washed you probably have a leaking nut kit. You'll want to replace both if either is not working properly.

If this has been going on for long you'll want to clean your EGR and install a new gasket while doing this job. Leaking fuel can also harm your cat, so you might have to look at that in the future too.

If fuel pressure is good, and you don't have a leaking regulator check spark.

Good luck.


Thanks for the tips.. I've just recently (3 months ago) replaced the EGR valve...

about a year ago I replaced the CPI and nut kit.. however I haven't checked that out yet to see if it's washing under the plenum again...


I'll check the fuel pressure when I get home... and put on new o2 sensors.. if I can find them.. (not sure where they are on my 95 Vortec)

new spark plugs same time as the EGR valve (3 months ago)

haven't check the fuel filter yet tho.


Thanks,
vballfun

No, I don't think so. While your first symptom (gassing at 40mph causing a stall) doesn't match what I'm about to describe, you'll want to check your fuel pressure anyway. There's a shrader valve on the inlet fuel rail that connects to the back of your intake manifold; check the pressure there. If it's not between 60-65 try replacing your fuel filter.

You'll also want to see if you're one of the many '95 owners that has a faulty fuel pressure regulator. To check, remove the vortec nameplate from the top of the upper intake plenum, take out your IMTV and look in to the intake. A properly working injection system will be indicated by a grimy carbony blackness inside the entire manifold. A faulty injection system will be indicated by clean or golden spots, and puddles of fuel. If the passenger side is washed you probably have a leaking fuel pressure regulator. If the drivers is washed you probably have a leaking nut kit. You'll want to replace both if either is not working properly.

If this has been going on for long you'll want to clean your EGR and install a new gasket while doing this job. Leaking fuel can also harm your cat, so you might have to look at that in the future too.

If fuel pressure is good, and you don't have a leaking regulator check spark.

Good luck.

checked under plenum.. nice and dirty.. I've got fuel pressure as well
.. but I think it was only around 40... not the 60-65 you recommend.. so maybe could be fuel filter.. Is it supposed to be at 60ish when you put key in and turn to 'aux' power position?

tried starting car again and it started after trying for about a minute.. then I turned it off to see if it would start again and no luck.

got cold tonight so will try the fuel filter tomrrow.

vballfun

Search for CPI injector

Search for CPI injector

I just replaced my CPI about a year ago.. I looked inside the plenum (under the Vortec cover) with a flashlight and it was nicely black.. no washing.

plus fuel pressure held (at around 40 psi) and didn't dissipate which i thought means that the CPI isn't leaking...

40 psi is low but I don't know if that is low enough for engine to not start. going to change fuel filter which hasn't been changed in over 150,000 miles and see if that helps the pressure get up to around 55-60 psi before I pull the plenum off again.

thanks,
vballfun

I just replaced my CPI about a year ago.. I looked inside the plenum (under the Vortec cover) with a flashlight and it was nicely black.. no washing.

plus fuel pressure held (at around 40 psi) and didn't dissipate which i thought means that the CPI isn't leaking...

40 psi is low but I don't know if that is low enough for engine to not start. going to change fuel filter which hasn't been changed in over 150,000 miles and see if that helps the pressure get up to around 55-60 psi before I pull the plenum off again.

thanks,
vballfun

40psi is low and the fuel pressure should be between 56-64psi.

You should remove the plenum cover and check the nut kit as well to if it is leaking.

The fuel pump could be weak as well or the battery and charging system that is supplying the pump might not be supplying the 12+ volts or the appropriate current it requires to get the pressure that high.

Smell any gas leaking? It could be possible that your fuel rails may be leaking where they connect to the intake manifold. First thing's first, change that fuel filter man. Cheap part and easy to do.

edit:

going to change fuel filter which hasn't been changed in over 150,000 miles

lol I missed that. That's likely your problem bro :)

Smell any gas leaking? It could be possible that your fuel rails may be leaking where they connect to the intake manifold. First thing's first, change that fuel filter man. Cheap part and easy to do.

edit:



lol I missed that. That's likely your problem bro :)


I'm hoping it's as easy as that.. it would make my thanksgiving a lot better ;) getting off work in an hour and changing it then.

no gas smell.. however for past month exhaust has been smelling odd.. not quite what it smelled like when I was dumping fuel out of my CPI back when it was busted.. but it definitely has a different 'stink' to it.. maybe that's what running 'lean' smells like??

-vballfun

I'm hoping it's as easy as that.. it would make my thanksgiving a lot better ;) getting off work in an hour and changing it then.

no gas smell.. however for past month exhaust has been smelling odd.. not quite what it smelled like when I was dumping fuel out of my CPI back when it was busted.. but it definitely has a different 'stink' to it.. maybe that's what running 'lean' smells like??

-vballfun
One thing that could be causing the 'stink', is that your catalytic converter is cloger... and in the futher could cause some more problems for your engine. like bad gas mileage, and your spider's messing up.

One thing that could be causing the 'stink', is that your catalytic converter is cloger

agreed... This is probably your worst case scenario possible right now (which isn't too bad). When you're leaking fuel you can wreck your cat pretty quick. Did you have any indication of how long fuel had been leaking for when you changed your CPI? Wouldn't cause the fuel pressure problem though.

I myself am going to be changing my cat out in the next couple months... when I changed my CPI it had obviously been leaking for a while.

Well I went to work on the truck last night and rehooked up the fuel pressure gauge and now I'm not getting -any- pressure... grrr
(before I changed the fuel filter)

not hearing the pump start up either when i turn the key

replaced the fuel filter.. and didn't get any better pressure..

going to try to figure out how to test the fuel pump now..

there's supposed to be a red wire under the hood on the left fender that you can jumper to test the fuel pump.. just haven't found it yet.

chiltons says that the CMPI unit also controls the fuel pump so if it is the CMPI unit bad then that jumper should start the fuel pump and I know to replace the CMPI 'spider' again.

oh.. and happy thanksgiving everyone :-)

vballfun

no the injector does not control the fuel pump.

If you are not getting the fuel pump priming when the key it to the first position, then your fuel pump is probably shot.

What LT said... the low fuel pressure was probably the pump on its last legs. If your fuse is ok and it isn't priming then you've found your culprit.