94 Blazer starts, dies and starts later

My sisters 94 Blazer 4x4 4.3 died at our house the other day. She drove it to our house(90 miles). She said it killed on her once on the way here. It started again and she drove the rest of the way. I checked some posts here and my brother and I replaced the fuel pump and fuel filter. We started it this morning and it ran for 10 minutes and died. It won't start now. We bought a fuel pressure gauge. What is the correct cold start pressure? Other postings have suggested the crank shaft sensor, where is this located, we have a spare 94 blazer at our house to borrow parts from. HELP!!!!!!!

Just wanted to add there is no check engine light on.

If a Z engine code TBI the fuel pressure specs is 9-13 lbs of fuel pressure.
First check for spark to spark plugs when it no starts.
Then if spark move on to fuel pressure..
Post back what you find.
MT

If a Z engine code TBI the fuel pressure specs is 9-13 lbs of fuel pressure.
First check for spark to spark plugs when it no starts.
Then if spark move on to fuel pressure..
Post back what you find.
MT

Unless I missed something, 70impala did not mention anything public about a Z engine code. The fuel pressure specs for a 4.3 W engine code W are radically different. Somewhere between 58 and 62 psi (going by memory here, there are many posts listing the exact values). I agree, if no spark (that is, good spark) then check fuel to engine.

My 93 pulled this stunt last winter. The ignition module was failing. When it warmed up it would die. Check that fire. Good bet it is weak or non existant.

Unless I missed something, 70impala did not mention anything public about a Z engine code. The fuel pressure specs for a 4.3 W engine code W are radically different. Somewhere between 58 and 62 psi (going by memory here, there are many posts listing the exact values). I agree, if no spark (that is, good spark) then check fuel to engine.

That is the reason I asked and posted the specs on the 4.3 Z engine is on a 94 I do not show a 4.3 W engine.
We need to know for sure what he has.
MT

Her Blazer is the 4.3 vortec engine so it would not be the TBI. We have spark when it dies. It starts good cold and warms up to about 100 degrees and dies and will not start until it sits at least 20 - 30 minutes. We did not have the right fuel pressure gauge so we could not check it. There is spark so would this be the ignition module?

If you have spark the ign module should be working but make sure you check it when no start or right engne quits.
And also make sure the fuel pump is running.
If you have good spark move on to fuel pressure and injector pulse.
Does the fuel pump run when it quits? Have you checked fuel filter?
What is the 8 th digit in your vin no?
I still do not show a MPI or code W engine for a 94.
93 and 95 code W engines 4.3 the fuel pressure is specs is 55/61 lbs of fuel pressure.
Cold start or key on eng off fuel pressure should be 60-61 lbs after eng starts it will drop back 56-58 depending on engine load and should jump back up to 60 lbs full throttle or engine under load.
Also check for a fast leak down on fuel pressurev after engine is off.
Get a fitting for your fuel gauge and give us your fue pressure readings.
Does it have any check engine lights when running or codes stored?

Ok now I think Ifigured it out. Is it a S-10 Blazer instead of a Blazer?

OK, 94 S10 Blazer 4dr 4wd we have replaced fuel pump, fuel filter, fuel pressure regulator. Fuel pressure reads 55 - 58 at start up and holds this pressure after car dies. We sprayed carbed cleaner into breather and it started. For some reason it is not getting fuel after running 1 - 3 minutes. We are think ECM or faulty injectors.

OK, 94 S10 Blazer 4dr 4wd we have replaced fuel pump, fuel filter, fuel pressure regulator. Fuel pressure reads 55 - 58 at start up and holds this pressure after car dies. We sprayed carbed cleaner into breather and it started. For some reason it is not getting fuel after running 1 - 3 minutes. We are think ECM or faulty injectors.

Good fire and good fuel pressure and start with carb cleaner.
Yes it may be a injector or wiring circuit or pcm or pcm wiring circuit.
You might do the old tap or twist test on the PCM.
Drop it down and tap or twist it and see if it changes the running or no start part.
Also watch for injector pulse with a scanner or a injector pulse noid light.
In a few cases I have had the injector wiring that goes into the intake to injector get bad or lose or burnt inside intake.
Check for good injector pulse where the wiring goes into the intake and if good and pulsing there. Then look at injector wiring and injector unit inside intake. Also check the wiring plugin at injector.
Good Luck and let us know how it goes.
MT

For some reason it is not getting fuel after running 1 - 3 minutes.

There is one other test you might try which is very easy to do. Since the engine kills in such a short time, it might be doing so when the operating mode switches from Open to Closed loop.

Here is what my Chilton's says about it:

Open Loop Mode:
When the engine first starts and engine speed rises above 400 rpm, the computer operates in Open Loop mode unil specific parameters are met. In OPen Loop mode, the fuel requirements are calculated based on information from the MAP and ECT sensors. The oxygen sensor signal is ignored during initial engine operation because it needs time to warm up.

Closed Loop Mode:
When the correct parameters are met, the computer module will use O2 sensor output and adjust the air/fuel mixture accordingly, in order to maintain a narrow band of exhaust gas oxygen concentration. When the module is correcting and adjusting fuel mixture based on the oxygen sensor along with the other sensors, this is known as feedback air/fuel ratio control. The computer will shift into this Closed Loop mode when:
1. Oxygen sensor output voltage voltage is varied, indicating that the sensor has warmed up to operating temperature.
2. The ECT shows an engine coolant temperature above a specified level.
3. The engine has been operating for a programmed amount of time.

Field Service Mode:
When the diagnostic terminal of the test connector is grounded with the engine running (same connector and pins for reading diagnostic codes), the computer module will enter the Field Service Mode. If the engine is running in Open Loop Mode, the SERVICE ENGINE SOON Lamp will flash quickly, about 2 1/2 times per second. When the engine is in Closed Loop mode, the lamp will flash only about once per second. If the light stays OFF most of the time, the engine is running lean. If the light stays ON most of the time, the engine is running rich.

While the engine continues to operate in Field Service Mode, certain conditions will apply:
1. New trouble codes cannot be stored in computer memory.
2. The Closed Loop timer is bypassed.

I did the above test on my 93 4.3 Vortec W engine (starting with a cold engine) and could see the transition from Open to Closed loop take place.

Try it. All you have to do is plug in the jumper (I use a paper clip) after starting the engine and watch the flashing light.

Replaced the ECM and Blazer still shuts off after about 5 minutes and then won't start again for about a couple hours. Any ideas?

Replaced the ECM and Blazer still shuts off after about 5 minutes and then won't start again for about a couple hours. Any ideas?

Read post 11 before you replace the hole blazer.:grinyes: :lol:
You need to test it out before throwing parts at it.
Good Luck MT

We have a spare 93 blazer to use for parts. We do not have a injector noid pulse light so we have been replacing parts. We have power to the injector assembly. We replaced the whole injector assembly, ECM, and all the sensor on the top plenum. What other ideas do you have? Thanks!

If you have good spark and good fuel pressure and it starts on carb cleaner then the injector is not working or you are not getting injector pulse.
You need to start checking the injector pulse.
A scanner or noid light is the only to check for injector pulse.
Parts place will sell thm or rent them.
Good luck MT

In responce to your priviate message.
You need the injector noid light or a good scanner to check for injector pulse.
A test light will not do it and a may damage pcm.
Any parts place will have them. They are a little noid light that will blink if there is injector pulse.
http://tools.batauto.com/index.php?qry=noid+&x=9&y=5&action=show&mode=post&search_type=any&search_mode=simple
You have to have the injector pulse and proper fuel pressure for the injector to squirt fuel.
MT

Here is a cadalic of noid lights.
I wish i had one of them.
http://tools.batauto.com/index.php?crn=85&rn=851&action=show_detail
Good luck and happie injector pulse testing.
Let us know how it goes.
MT

Here is a cadalic of noid lights.
I wish i had one of them.
http://tools.batauto.com/index.php?crn=85&rn=851&action=show_detail
MT

No sense trying to diagnose fuel injection problems without one. Not very expensive considering the amount of time to be saved or $$ throwing parts at the problem. BAT Looks like a good source for tools. I bookmarked it.

We figured it out. We had spark but we switched ignition modules from our parts vehicle anyway. Problem solved. Thanks for the help!

Thanks to everyone for their help!

Thanks to everyone for their help!

Thanks for posting back and letting everbody know how it went.
Glad you go it going.
MT