Hi-this is regarding a 95 4.3L Blazer vinW.
Before I get to the problem, here's some background--last year one of the internal fuel lines cracked; couldn't find the part so a friend made one for us in his shop. He couldn't get it exact and it was a little too long but seemed to work, truck ran fine, no problems. After a few months the engine light started coming on, but truck was running fine. Codes called failures in O2 sensor, cat converter, and EGR. Couldn't seem to find the problem, and light would go out after a while. Then started having a problem with the truck cutting out when it would get too warm--only happened when the outside air temp was over 88 degrees and truck had been running for a while. Normally runs about 160 degrees, but when it would get hot outside, the temp guage would get up to about 210, then truck would die, and would not re-start until it cooled down. Whenever this happened, the fuel pump would whine when you try to re-start. This is a new pump straight from GM (got sick of after-market pumps croaking and finally got a "real" one), so we knew it should not be the pump going again. Also, sometimes this would happen when the SES light was on, sometimes not. Checked crankshaft, ignition module, & coil---all fine.

So, lemme stop there and see what you guys think so far...more to follow...

*COMBINING THREADS*
Title: 95 4.3 Blazer--Problems Part II...after nut kit
Posted: 8/9/2007 8:54:33 PM in 'Engine & Internal'
Action Taken: *THREAD LOCKED*

So, by process of elimination, we figure the problem with the truck cutting out and the fuel pump howling *must be* due to the slightly-too-long internal fuel line crimping when it heats up. Logically, it makes sense, right? So I go to the blazerforum and learn that we need something called a nut kit; we get one at NAPA, DH and BIL install it, put the truck back together and viola! it runs like ****!! What in the world? It was actually running great before, as long as it didn't get a little warm. Now it is running like it's about to die any minute, misfiring like crazy. So they took it all apart, checked everything, looked fine, put back together, still running like crap. SES light is not only on, but flashing (what does THAT mean??) Code kicking is "Multiple misfires." Well, no duh. So, any ideas about what to check next?????

*COMBINING THREADS*
Title: 95 Blazer runs bad after fuel line fix
Posted: 8/10/2007 9:34:59 AM in '2nd Gen (1995-2005) Tech'
Action Taken: *THREAD LOCKED*

The other day we replaced the internal fuel feed and return lines, and now the truck is running like crap! The SES was on and flashing. I thought the flashing meant that it was throwing different codes. Unfortunately, now the only code it's reading is 0300 (why do they even HAVE that code??). Any ideas?
The truck was running pretty well before the fuel lines were replaced, except it would cut out sometimes when it was warm. Normally engine runs at around 160 degrees or so, but if the outside air temp was over 88 degrees and the truck had been running for a while, (like on the freeway for at least 30 minutes) the temp guage would creep up to about 220 and the engine would quit. When you tried to re-start the fuel pump would howl and it wouldn't start. But after sitting for a while it would start again. Also during this time the SES light would come on for a while, and then go out, just under normal city driving conditions. But as far as running, the engine was running great-smooth, quiet, getting normal gas mileage. About 6 months before this started happening, we had replaced the internal fuel feed line which was cracked. However, the replacement line we used was "made" for us in a friend's shop, and it was not exactly the right size, it was a little too long but it worked. Then we started having the problem with the truck cutting out. Husband figured since

 

Wow... I'm sorry that you are having these problems, but you don't need to spread your problem out in several different threads... That confuses the issue...

Now, after reading through pretty much the same thing in the 3 threads I combined above, It seems to me that something wasn't done correctly when you installed the new 'nut kit'. Is it possible that you got some trash in the lines and that has now clogged the electronic injector or poppet nozzles? Have you attempted to verify the spray pattern of the nozzles? Are you sure there are no leaks...?

 

Sorry about that; I didn't have time to post the whole thing at first, and then I thought maybe I posted in the wrong forum. Sorry. Anyway, yes, they checked everything, and as I was posting this morning they replaced the injector "spider" and that didn't fix the problem. No leaks. Unfortunately it is my husband and his brother doing the work, so I don't have "firsthand" knowledge. But I ran your ideas by my husband and he asked what do you mean by "verify the spray pattern" of the nozzles? Thanks a lot for your thoughts.

 

This is very difficult to do without the proper tools, but what I mean is to pull the poppet nozzles out of their bores and actuate the injector to spray fuel out of the poppet nozzles. If you actually can do this, you'll want to have all of the nozzles out and over some kind of a container to catch the spraying fuel. You should get a nice fine mist out of the nozzles. If it just dribbles out, then your nozzles are bad... But if they replaced the spider with a new one, then that isn't your problem.

At this point, it could be a problem with the fuel supply to the spider... If you do not have 55-60psi at the fuel pressure test port, then you will not get a good spray pattern or the required amount of fuel out of the injection system.

 

Truck continues to sound and run like a lawn mower.
Was showing a TPS low voltage code this morning, so today replaced the TPS, then got the dreaded P0300 code. Have also today replaced crankshaft position sensor, ignition control module, plugs & wires. (Didn't do cap/rotor since they are fairly new.) Yes, we had the computer re-set. Seems to me the problem MUST be related to the nut kit job. Husband and brother in-law insist they double checked fuel line connections and everything, and checked for vacuum leaks. Autozone guy thinks it's the coil--would the truck even start if it was the coil??
Please, any other suggestions would be really appreciated. I'll search on P0300.

 

Have the computer re-set? I have a 97 4.3L 4WD with starting problem and have changed out a lot of what you have. So, how do you reset the computer?

Thanks,
Frank

 

Maybe I used the wrong terminology (i.e. "computer re-set.") --we had the codes cleared.

 

Ok, I thought there might be something additional to "reset" the computer. I've heard that some of the newer cars need the computer reset, not just codes cleared if there is a loss of battery power to the computer. thanks for clearing that up.

 

Replace your cat.
Your cat is plugged up. The engine dies because the cat is not allowing the hot exhuast gases to vent, tehy back up into the engine. Your P0300 is becuaseyou disconnected your battery. Once you disconnected the battery it lost the information it had to adjust the engine timeing to run with a plugged cat. Since you disconnected teh battery the puter reset to defualt settings and now those settings will not adjust hte engine timing enough to make it run well.I think your chasing the wrong parts. Look at you r main glues,02 codes,your engine dieing when hot, coolant temps rising all add up to a plugged cat... Think about it.

 

Hello I own me a Blazer 4dr 4x4 ls with say 100000 miles and my check engine light came on was gonna get it checked but then it went out and thought hmm now what then say a month later it came on again and i just happened to be drivin by an autozone so i pulled in and got it checked the guy gave me a print out and heres what it says

troubleshooting P0101

The pcm has determined that there is a discrepancy between the "actual" mass air flow input and the "calculated" mass air flow input derived from the input gathered from other sensors ie: throttle position sensor, barometric pressure senor ect.

troubleshooting P0101

definition
MAP(man. absolute pressure)/BARO or
MAF(mass air flow)/VAF(vane air flow)
sensor condition

Explanation
All vehicles have one or more of these components. Engine load or the air volume entering the engine is measured by these components. The computer has recognized a return signal error.

Probable causes
1. vacuum hose off, cracked or passage blocked engine mechanical timing condition
2. throttle body intake tube loose, off, or cracked
3. BARO (barometer)/MAP (manifold absolute pressure) defective
4. VAF (vane air flow)/MAF (mass air flow) sensor dirty or defective


with this in hand where do i go about starting to find out the problem i dont wanna just go out and buy all these sensors when it could just be 1 i know i need em all but i would just like to fix why the light keeps coming on for now i know my way around and can fix things on my own just need guidance or knowledge on which to try first to help me save money any information would help me a great deal