Blazer Won't Start

[eriq1220]

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?

[MT-2500]

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

[lobstamon]

Originally Posted by MT-2500

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!

[corning_d3]

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

[MT-2500]

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

[lobstamon]

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

[lobstamon]

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

[MT-2500]

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

[Blazer SS]

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.

[lobstamon]

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!

[MT-2500]

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

[MT-2500]

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

[lobstamon]

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!

[MT-2500]

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

[lobstamon]

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