Blazer Won't Start

Hi,

I have a 1998 blazer. I cannot get it to start. It gets power. It turns over, and the engine turns. However, I think fuel cannot get to the engine. I'm thinking it could be the pump, filter, or maybe a sensor. It didn't start for a week or so. Then, once it got above freezing and I put HEET in the gas tank, it started. Then a day or two later it wouldn't start again and I have not been able to get it started since. Any ideas on what to look at?

You need good hot spark and good fuel pressure up to specs and injector pulse.
Start with spark to two or more spark plugs if you have spark move on to fuel prssure.
And if fuel pressure is good check for injector pulse.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

Let us know what you find.
MT

You need good hot spark and good fuel pressure up to specs and injector pulse.
Start with spark to two or more spark plugs if you have spark move on to fuel prssure.
And if fuel pressure is good check for injector pulse.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

Let us know what you find.
MT

How (exactally) do you check for injector pulse?
I know, I read over 10 bad/low fuel pressure replys... I have 64 PSI @ the test port, no leak down during sitting or cranking.
If I pour fuel in the Carb looking thing w/o fuel lines, it starts until the gas is gone. Do I remove the black manifold & keep the electric/fuel lines hooked up & look for squrting or what?
What wires do I test? What colors? Where?Can I use a VOlt meter w/ a bar graph?
THANKS!

That sounds like watered down gas......

What engine and engine code.
You can check for injector pulse reading with a good scanner or us a injector node light tester on the two wire going to the injector.
If it blinks you have injector pulse.
A volt meter will not work.
MT

Vortec 4.3 1997. I checked the pressure again. It was 67@ cranking, 55 after cranking, but holding that pressure. As soon as you turn on the key, you get 60-62 PSI. Always 67 PSI @ Cranking. The engine "hits" sounds like the ignition and/or fuel is on every other time. Yes, the Blazer has a security system (Hornet, I don`t know how to disable, I was told to hold the button under the dash).The fuel smells/feels good (no water, I`m a industrial/Marine mechainic for many years, I know the difference).
I purchased the Blazer in a goverment auction, was told in 2003 the vehicle was drove & parked.
Despite the fuel being 3 years old, it smells/feels strong (I know the "feel" of good/strong gas).
There is a intake manifold leak, which caused the radiator to need a qt. of water. There is some signs of leakage on the #1-3 intake to head ports. I doubt if this has anything to do with a NO start though.
I have a generic code reader that dives me a "intake pressure" code.
I don`t have a noid light or any other equipment.
Since it`s a No Start, I was hoping it was something obvious.
HELP!
Don

The picture under your name is a vessel bridge, is it a boat or plane?
I`m a marine mechainic. Though I quess the big difference is how much air/water do we have left before we crash/run aground!
Don

If you still have good spark to plugs and good fuel pressure next step is check injector pulse. Read out on a scanner or a injector node light node is the best way to check injector pulse.
Some security systems will shut off injector pulse or starter.
But on the hornet system I know nothing about it.
You might run a web search on hornet systems and find out something.
Is the pressure code a map sensor code or what no is the code?
Good luck MT

The more that I read, the more it sounds like one thing that was already pointed out, WATER. After it was stored was the tank ever drained? Then after adding something to the tank it probably isolated the water to the bottom of the tank. Water can't go through fuel injectors. A small amount of fuel does make it by. If you want to try something while turning the key to the first click look at your security light on your dash it should either flash or be steady then it should go out. if it stays on your security is activated. Read your owners manual it tells you what to do. I forgot to add the security cuts power to the fuel injectors preventing the truck from starting.

No,
The tank wasn`t drained, & I too thought the water theory was a(VERY) good one. I`m a marine mechainic & I`m quite accustomed to water in the fuel problems. Water & fuel don`t mix, they seperate(like oil/vinigar). The water beads off over the fuel if you were to squirt a sample out of fuel/water.The water also adds a "stale" smell to the fuel, and, when it get`s on the skin, just doesn`t have the same "bite" drying effect (that`s the best I can describe good/bad fuel from my 30 years experience).
Water is heavier than fuel & would stay @ the bottom. From what I recall, from the other Blazer I won from the same auction,I had to replace the fuel pump, & I found,the pump pumps from a few inches above the bottom, when this level is reached, there is a ball, which closes the higher port & then reverts to the bottom/lowest pick up.
I should collect a sample of the fuel, let it stand & see if it seperates...that is what I do for my customers, ....I`ll check it & post my findings.
I just checked the security light, there was none, but, the lights/electrical system is acting wierd (I am looking into disabling the security system to take it out of the loop).
Is it the function of this noid light to check the injector pulse? Can I check with a frequency meter? is there a given pulse rate @ a given RPM?
Or, am I just being cheap? How much is a NOID light?
Thanks for all you guys tring to help, I really appreciate it!

The injector pulse is a grounded modjulated signal.
A lab scope will test it or low amp draw neon bulb or a injector testing node light works best. They are not very expensive 15-30 $.
Or if you can get a scanner on it you can check injector pulse with a scanner.
Good luck and let us know how it goes.
MT

The injector pulse is a grounded modjulated signal.
A lab scope will test it or low amp draw neon bulb or a injector testing node light works best. They are not very expensive 15-30 $.
Or if you can get a scanner on it you can check injector pulse with a scanner.
Good luck and let us know how it goes.
The pulse rate always varys acording to engine load and engine tempture. controled by pcm.
MT

The fuel sample was clean, good, strong red gas(not rusty).The volume was strong as well. I made several attempts to contact Hornet, the security system manufacturer, they had me on hold over an hour both times! I hope thier toll-free phone bills reflect it as I`m located in the Virgin Islands.
Let me ask you this, does the computer under the hood supply this pulse? I still have the other blazer which runs good (other than a strong gas smell, I`m told may be a fuel regulator...where is it??) A noid light was $127 @ Western Auto!!! & it was not in stock! Things are quite expencive here...
what IS the voltage supplied to the injectors?We have a Radio Shack, I can purchase/fabricate a light from.
Is the injection system simply a high pressure fuel pump feeding these normally closed injectors that open with oscillating voltage to some built in electric solinoids in the injectors? what references or tells the injectors to unload?
The computer looking this is in some plastic air cooled bracket, on the passinger side.
If I`m on the right track, can the security system be set up to spark everyother time or so & maybe screw this test up as well? I would think it would be much easier to just kill the voltage to the fuel pump or ignition.
I agree w/ MT-2500, I`d like to know if there is a *&&^%$## pulse to the injectors. To be truthful,I`m not even sure where the injectors are located! I suspect it`s behind the carb looking air intake where the metal fuel lines go with a bunch of wires, it`s a Vortec V6 1997. I looked around for the error code # (I wrote it down, I can`t find the paper & I erased the code!)I remember it was related to a air intake pressure code.
I`m sure if I can understand this thing, I can fix it.
Thanks again for all the help!

If a 97 here is a pdf wiring diagram of pcm showing the injectors wiring.
http://members.troublecodes.net/crunch/97b.pdf
On the 97 the injector wiring plug in goes into the top of upper intake.
The injectors are pulsed onthe ground side with a grounded modjulated signal from the PCM.
With a small neon bulb you could make a injector node ligh or pulse light.
Hook one side to 12 volts pos and the other side to the injector ground pulse wire.
When the pcm ground pulses the injector the light should flash/blink.
But if it is a 97 that rings a bell on bad ign switches.
Check all key on and key off 12 volt power feeds to the pcm and other stuff.
The PDF wiring will give the 12 volt pcm feeds.
Good Luck
MT

Hi MT,
I got a pulse from the negative injector leads(I built a noid light from a super bright bulb @ Radio shack, I use a bread tie wire to insert the probe into the wire @ trhe plug), but, once the engine starts (I adjusted a drip-fuel system from my refridgeration guages over the air intake, with the supply fuel comming from the test port) and the engine runs,the pulse gets weaker & weaker, then nothing, no pulse. The code I`m getting (everytime I start it) is P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage.
I`m guessing the !@###$%^& alarm system is causing the injectors not to pulse well enough by killing the ground, or the ground that feeds the computer is breaking down (I tried changing the computer w/ the running Blazer),or I`m missing something. What does the code P0108 mean? Is the code a result of the injector pulse malfunction, or is there back pressure or something?
If I supply the injectors with a constant ground, shouldn`t the engine run (very rich) as the injectors are open? Or could this mess up the computer?
Can I perform the same test while monitoring the fuel pressure drop (with the engine off)?
Sorry for all the questions, but, atleast I`m hunkering down on this!
Thanks again,
Don

The injector pulse that controls the injectors is a modjulated ground pulse.
I do not thing a straight ground on them will work and may damage injectors.
If it loses pulse running something in the pcm/or sensor input reading to it is shuting down pulse.
You really need a engine scanner to read out what the pcm is doing.
The 108 map sensor code is for high map sensor reading or low vacume.
One thing to check is the crank sensor and tps and map and coolant temp. affect injector pulse.
Try unpluging tps and map and coolant tempt sensors.
But without a scanner is is hard to pinpoint what the pcm and injector control is doing.
A good one year all data DIY repair info sub 24.95$ a year may help.
Or if you can find a factor repair manual would help you.
It has all of the repair info and wiring on it.
Link below.
http://www.alldata.com/products/diy/index.html
Good luck and let us know how it goes.
MT

OK,
The original post was wondering if fuel was getting to his engine (which attracted me to this thead).
I removed the black plastic upper intake 1/2, I unplugged the wires to the fuel spider & connected 12 volts to the injectors one by one. 5 of six injector poppets would not open despite my good fuel pressure. The one that opens, puts out a good spray until (I suspect) the pressure drops enough that the spring seats the valve despite the constant 12 VDC applied to the coil(I didn`t have my guage connected @ the time).
I removed all the poppets & reconnected the spider, all lines sprayed, proving the injectors. It seems the poppets (located @ the end of the fuel line) is the smallest orafice in the system & is what most spiders have replaced when "rebuilt".
All the pink wires are the same, & apply 12VDC positive, while the other 6 wires are the negatives. If you apply 12VDC to any of the pink wires, it also turns on the fuel pump (good to know).
So, it turns out (so far) the dam poppets (5 of 6) were dead a$$ plugged!
Too bad I didn`t energise the funtional injector/poppet, the fuel pressure would have dropped.
So, you CAN test for plugged poppets (are non-funtioning/plugged injectors) by appling 12volts & watching the pressure drop one by one.
My next question:
What is the pipe the poppet(nozzle) black connector connects to? is it just a clear pipe? can I push a wire through it? or is it a tuned orafice I should clear with air??
I hope someone else can benifit from my tests.
Thanks to MT-2500 for the scematic/help.

By pipe I mean the one on the intake that feeds the cylinder intake port.
Thanks

Be carefull there. You can burn up the injectors and VCM to.
I do not think that is the way to test injectors.
MT

I unplugged the VCM.
I agree, it`s not the best way, but were checking for a no start here on a vehicle that runs with fuel in the throttlebody.
Burn up the injectors? Aw, what the hell. I`m gonna replace the spider anyhow, let me make some tests!
Test results:
injector coil resistence:(average) 13 ohms. Since ohms is (roughly) the same as voltage for a coil that could be energised for a few minutes (better than intermitent, but not continuous duty).
Current (tested @ 12.5 VDC) (average) .65 amps.
Heat: injector got comfortabbly warm after 15 seconds.I`m not suggesting to do this to an injector your going to want to use, but I really don`t see any problem with appling battery voltage for a second to see if the injector opens @ the poppet or not.
even after abusing the injector for 1/2 a minute, while it got sort of hot, still snaps open strong & still reads 13 ohms indicating the windings havent shorted or opened.
For those into destuction....
The smoke test:
I applied 19 VDC for 10 seconds, the injector survived. 12 seconds, OK. 15 seconds....OPEN COIL<< means this injector is fried!
My question remains, what of the pipe that the poppet connects to which is in the intake manifold, how do I clean/check if it`s clear?
Thanks!

I unplugged the VCM.
I agree, it`s not the best way, but were checking for a no start here on a vehicle that runs with fuel in the throttlebody.
Burn up the injectors? Aw, what the hell. I`m gonna replace the spider anyhow, let me make some tests!
Test results:
injector coil resistence:(average) 13 ohms. Since ohms is (roughly) the same as voltage for a coil that could be energised for a few minutes (better than intermitent, but not continuous duty).
Current (tested @ 12.5 VDC) (average) .65 amps.
Heat: injector got comfortabbly warm after 15 seconds.I`m not suggesting to do this to an injector your going to want to use, but I really don`t see any problem with appling battery voltage for a second to see if the injector opens @ the poppet or not.
even after abusing the injector for 1/2 a minute, while it got sort of hot, still snaps open strong & still reads 13 ohms indicating the windings havent shorted or opened.
For those into destuction....
The smoke test:
I applied 19 VDC for 10 seconds, the injector survived. 12 seconds, OK. 15 seconds....OPEN COIL<< means this injector is fried!
My question remains, what of the pipe that the poppet connects to which is in the intake manifold, how do I clean/check if it`s clear?
Thanks!

No use to worry about it now. You have already destroyed the injectors, which is a part of it.
We are here to help people repair cars and are not here to help anyone create mass destruction on there 500-750$ fuel injector system.
I am sure if you work at it hard enough you can figure it out on your own and a way to destroy it to.
Good Luck MT

No use to worry about it now. You have already destroyed the injectors, which is a part of it.
We are here to help people repair cars and are not here to help anyone create mass destruction on there 500-750$ fuel injector system.
I am sure if you work at it hard enough you can figure it out on your own and a way to destroy it to.
Good Luck MT

Destroyed what? A fuel injector spider that has 5 of 6 totally non-operational injector/poppets???
Yes, "We are here to help people repair cars and are not here to help anyone create mass destruction on there 500-750$ fuel injector system".
But what DID I destroy? What value does that spider I destroyed have?? My Blazer sure didn`t run very well one one cylinder!! OK, offer me 1/6 of $500 for it, I`ll sell it to you!
Due to the lack of information here & elsewhere, I "destroyed" my (already useless) spider in the name of data (don`t be affraid to gather it, especially if it`s *free*.
It`s not mass destruction, only data, the fried injector wasnt even slightly amusing, (it didn`t even smoke, it`s coil mearly opened= no continuity).
You STILL haven`t addressed my question , but I suspect you don`t understand it. Your answer to it was irrelevant, & didn`t remotely apply.
Below, please find the correct answer to the question I had earlier posted by BLAZEE. He doesn`t think thier worth cleaning either!
So, what is this broken piece of junk worth to you? Offers??
Below post by Blazee:
Re: Can you clean injectors?
Personally, I prefer Techron. It is the most effective injector cleaner that I've found.

The compressed air treatment is not something that you can do yourself. IMO this service is not worth it. The price that the dealer charges is comparable to the cost of a new updated MFI system if you own a 96+. The poppet valves on the injection systems prior to 96 don't have the problems that the newer ones do. This TSB contains info on the cleaning and the new MFI system:
http://www.myfilehut.com/userfiles/13931/059041%20CLEAN%20CSFI%20POPPIT%20VALVES%20OR%20CON VERT%20TO%20MFI.pdf
__________________

No use to worry about it now. You have already destroyed the injectors, which is a part of it.
We are here to help people repair cars and are not here to help anyone create mass destruction on there 500-750$ fuel injector system.
I am sure if you work at it hard enough you can figure it out on your own and a way to destroy it to.
Good Luck MT

Read my lips. You have already destroyed the injector which is part of it.
Never did see one have 5 bad injectors.
Sounds like you destroyed five good injectors and keep the dead one.
But now you happie because you can replace them right.
Good luck MT

Read my lips. You have already destroyed the injector which is part of it.
Never did see one have 5 bad injectors.
Sounds like you destroyed five good injectors and keep the dead one.
But now you happie because you can replace them right.
Good luck MT
If you recall,
The vehicle sat since 2002. No, it`s the other way around, 5 of 6 poppets are complely clogged & don`t shoot one drop of fuel. Yes, all of the injectors were good until I fried one (in the name of data), the poppets are what clogged, which rendered the fuel injection spider useless.
Individually removing the poppets proved difficult, but possible. They were able to be cleaned with heat & high pressure air (now they all squirt!).
The problem is, re-installing them to the old fuel lines....it seems the old lines are brittle from heat/age, have a clear, reducing/sealing insert made for one time use & make poppet re-insertion difficult.<<what I`m saying here is, even though I was able to get the poppets clear, I wouldn`t trust the fuel line to poppet connection<<<in use, the fuel line may blow off the poppet! One couldn`t prudently rely on it!
The bottom line is, this fuel injection system is non- servicable (unless a poppet/fuelline kit is availible) <<it seems the connection to the injector would be easier, but a one-time connection.This might be heat shrinked, one time deal as well.

As we both found out, there is no simple solution to badly clogged poppets.I would imagine, the injectors could be opened with 12VDC,one by one, the regulator removed & back flushed with very high pressure air in an effort to clear them. this may work for some before resorting to replacing full injection spider. Then,the fuel cleaner/additives would only be usefull if then there is fuel flowing through the system which may restore it.
Since you never seen 5 of 6 clogged, maybe you only work on running, or just recently stopped running 4.3`s
The pipes that the injector spider poppets DONOT include, nor are they part of, the fuelinjector spider assembly, it is a seperate part installed on the intake manifold.Which is what I`m asking about (& you don`t seem to understand/address)
Thanks for the scematic & prior answers though, which were helpful.
I HOPE, you can understand why the intake pipes are NOT "part of it" already!!!!
They are seperate, they DONOT come with (nor are part of)the injector spider assembly!
If you ask me, the injector spider was a dumb ass idea, an easy transistion for GM to make from the single TBI injector.
This was done for $$ reasons, I`m sure.

If you recall,
The vehicle sat since 2002. No, it`s the other way around, 5 of 6 poppets are complely clogged & don`t shoot one drop of fuel. Yes, all of the injectors were good until I fried one (in the name of data), the poppets are what clogged, which rendered the fuel injection spider useless.
Individually removing the poppets proved difficult, but possible. They were able to be cleaned with heat & high pressure air (now they all squirt!).
The problem is, re-installing them to the old fuel lines....it seems the old lines are brittle from heat/age, have a clear, reducing/sealing insert made for one time use & make poppet re-insertion difficult.<<what I`m saying here is, even though I was able to get the poppets clear, I wouldn`t trust the fuel line to poppet connection<<<in use, the fuel line may blow off the poppet! One couldn`t prudently rely on it!
The bottom line is, this fuel injection system is non- servicable (unless a poppet/fuelline kit is availible) <<it seems the connection to the injector would be easier, but a one-time connection.This might be heat shrinked, one time deal as well.

As we both found out, there is no simple solution to badly clogged poppets.I would imagine, the injectors could be opened with 12VDC,one by one, the regulator removed & back flushed with very high pressure air in an effort to clear them. this may work for some before resorting to replacing full injection spider. Then,the fuel cleaner/additives would only be usefull if then there is fuel flowing through the system which may restore it.
Since you never seen 5 of 6 clogged, maybe you only work on running, or just recently stopped running 4.3`s
The pipes that the injector spider poppets DONOT include, nor are they part of, the fuelinjector spider assembly, it is a seperate part installed on the intake manifold.Which is what I`m asking about (& you don`t seem to understand/address)
Thanks for the scematic & prior answers though, which were helpful.
I HOPE, you can understand why the intake pipes are NOT "part of it" already!!!!
They are seperate, they DONOT come with (nor are part of)the injector spider assembly!
If you ask me, the injector spider was a dumb ass idea, an easy transistion for GM to make from the single TBI injector.
This was done for $$ reasons, I`m sure.
On the 96+ systems each of the 6 individual injectors can be removed and replaced individually. Each injector comes with the fuel line and the poppet attached. They cost about $50 each. For $200 you can remove the whole assembly and replace it with the updated MFI system. The MFI system doesn't have the poppet valves, it has 6 mini injectors where the poppets were.

Did you pull the poppets off all your injectors or just the two that were bad?
If you pulled the poppets off of all of them, you pretty much trashed your whole assembly, in which case, I'd recommend the MFI conversion.
If you just pulled them off the two that were bad, then you can just replace those two injectors.

Here's a picture of one of the individual injector/poppet assemblies:

http://www.smpcorp.com/web_app/catalog/images/FJ224.jpg

[/QUOTE]Did you pull the poppets off all your injectors or just the two that were bad?
If you pulled the poppets off of all of them, you pretty much trashed your whole assembly, in which case, I'd recommend the MFI conversion.
If you just pulled them off the two that were bad, then you can just replace those two injectors.[/QUOTE]

5 of 6 injector poppets were clogged solid, I fried one of the injector coils by abusing it (on purpose, see previous).This engine has been sitting since 2002.
A rebuilder offered $20, hardly worth the shipping so, I removed all the poppets to see all the injectors operate, which they did((i killed the ignition).
I ordered a used bone yard complete spider that came off a good runing engine (that mixed oil & water) for $75. It has a 60 day guarantee.
The question I now have is, the pipe the injector poppet clip clips onto, which is in the recessed hole in the intake manifold(not the poppet itself) should I check it to see if it is clear? Is it just a clear pipe?
For the future, if poppet clogging is a nusance, does the MFI injector correct this?
Thanks!

The bottom line:
A good/used injector spider assembly repaired this engine & it runs quite well!The cost was $75 + shipping for a good used one.
Perhaps,(and I believe) the fuel filter element deteriorates after time, & allows big chunks of $hit to clog the poppets.
My brother who used to be a GM Mechainic found this possible, but has never come accross it himself (one would think the filter was made/designed to filter particles smaller than the poppet orafice opening it`s trying to protect in the first place!).
All I can say is, with fuel injection, clean fuel is the key. The filter is quite easy to replace, & is cheap.
This fuel injection system is not a proper injection system by a diesel fuel injection standard. Where which, the fuel injector is a precision direct injection in the cylinder & the injector fuel pressure needs to exceed the cylinder pressure & is generally generates 2000 PSI!
The GM high pressure electric fuel pump, pulsed injection system, is a cheap, 65 PSI electronic pulsed system, which is not even in the cumbustion chamber, but rather in the intake, before the intake valve.
While this makes the system simple as hell, it IS a cheap piece of junk that....works quite well!
To (finally) answer the pipe that the injector poppet attaches to questions I had... It`s just a dam open pipe, Not tuned or anything else.
One would hope, the injection occurs before ignition, where the cylinder head/intake was able to atomise this raw injection, but, this isn`t what I`m interested in on this thead, I was only into function,just starting the dam thing, not tuning!
Bottom line, you can power the injectors idividually, see the pressure drop (if the poppet fires & NOT see it if it don`t without taking anything apart/resorting to the lack of information here & elsewhare),.Just ground anywire that isn`t Pink & something(positives), wich will unload the injector(s).This will enable those to troubleshoot a fuel problem**FINALLY**easy.
Though a fuel pressure guage is essential (you need to start here if you have a fuel problem anyway....
Yeah, Radio Shack Lamps work as Noid Lights for those who can`t obtain one(weak pulse = quick pulse).
Hopefully, I helped.