Topic: Stalling Blazer 01 HELP

[samm00]

 This started after our 01 Blazer ran out of gas, now stalling happens on going down hill and seems to be in hot weather, the fuel guage is also inacurrate - any links - ideas - we also had intermittent O2 sensor codes in the winter??? We had a new filter and the fuel pump has been checked! Has also run ruff and has surged before stalling, backfires, no power, no revs  Just had the Crank Sensor changed and its still loses the RPM SIGNAL - Our garage now says have to wait until it dies completely as they have tried all their ideas - just a pile of junk at the moment!! All advice welcome

[barrie1]

SammOO Welcome to the Forum, How long before or after was the fuel Filter changed out on this vehicle. Has the Dist Cap ever been replaced and how many miles on which engine size is it. The more we know about this vehicle the more we can help you. 

[samm00]

Hi there, thanks for replying, we bought it used a year ago, its a 4.3L 4x4 LT, we havent changed the Dist cap, on test plenty of spark, however revs kept dropping from 600 - stall, it is hight milage with 213,000km but was in good condition. The fuel filter was replaced after I ran out of gas and it stalled, the sensor was changed today but it still stalled on the way home!!

[articsteve]

How exactly was the fuel pump checked?  You mentioned the gas gauge is no longer 100% accurate.  Did that occur after running out of gas?  Did the problems happen immediately after you ran out of gas.

[samm00]

The fuel guage was inaccurate before - hence I ran out!
They tested it on the computer and checked for pressure. After I put more gas in I drove for an houe towing a trailer up a steep hill on a hot day with no problems - but after it had  been standing for 4hrs on the drive back home it stalled coming down the mountain, it is now becoming more frequent. The same day my friend wired the towhitch lights and removed a fuse - any relevance??

[barrie1]

Yes there could be on this wiring as that fuse could be running something else like the electric fan for the motor. Many things are wired to most fuses as they generally do more then one job. Does the temp gauge seem to work correctly in this unit? Generally the 4.3 engine is a great engine that will run for many years problem free unless there is a glitch somewhere like you have currently. Have you heard the fan running since this occured? 

[articsteve]

Well I was hoping that you could tell me what the fuel pressure was with key on and then running.  Garage might not know correct pressure.

Still not clear on this.  You ran out of gas then filled it up and then it started acting badly and then you had it looked at and they changed the fuel filter.  Is that the right order of things?

The fuse was removed after it was acting up or before?  What fuse was this for?

No check engine light all this time?

[samm00]

The fuse was for the trailer hitch and was removed before the day the trouble began.
 I have heard the fan. Good to hear that the engine should be good!!
Temp seems to be central on the guage.
The check engine light did come on but hasnt come on since it was cleared in which time it has many stalls
When htey checked the pump they had the engine running and apparently there is always good fuel flow and pressure.
And yes you have the order of events right.
Thanks for helping

[articsteve]

The fuse was for the trailer hitch and was removed before the day the trouble began.
 I have heard the fan. Good to hear that the engine should be good!!
Temp seems to be central on the guage.
The check engine light did come on but hasnt come on since it was cleared in which time it has many stalls
When htey checked the pump they had the engine running and apparently there is always good fuel flow and pressure.
And yes you have the order of events right.
Thanks for helping

The fuse was for the trailer hitch and was removed before the day the trouble began

Lets assume the fuse was a stand alone fuse for the trailer hitch lights.

When htey checked the pump they had the engine running and apparently there is always good fuel flow and pressure.

"apparently" is not the best.  You really should have the numbers.  Running it should be 60-66 psi.  Return line pinched off should be 75-85 psi.  Those fuel pumps are real junk.  It is amazing that it is the original pump at 215K.  I would get a second opinion on the pressure.  It is a simple test with a dial gauge.

The check engine light did come on but hasnt come on since it was cleared

So what was the code?  That should be good clue.

EDIT:

Why was the Crank Position Senor changed?  Was that the code?

You should have them drive the vehicle while the fuel pressure gauge is attached to you can read it under load. 

[samm00]

Hi there
i have checked with the garage and your figures, the test was right on spec for the pressure. Unfortunately he says unless another error code appears or it completely dies he cant do anything - any other ideas??

[articsteve]

What did the code that was cleared say?  Why was the crank position sensor changed?

How soon after you ran out of gas did all this bad ass stuff start happening?  Immediately, one hour, two?

You know if it walks like a duck and it quacks like a duck it just might be a duck.  I still would be looking a the fuel delivery side of things.  Those fuel pumps are notoriously bad and you have 210K on it.  I would hook up a pressure gauge and drive it under load and watch for intermittent pressure.  Something crap could have been sucked up into the line when you ran out of gas.  Idling the pressure may be OK, but running  under load it might not.  Is the new fuel filter installed correctly and not reversed.

[samm00]

The code was for the Crank Sensor
This stuff happened on my return trip home the same day, I had driven with a trailer left it and then drove home 4hrs later on a hot day and a steep hill down back.
Filter has been checked as fitted correctly
I will see if they can test under load as you suggest, if something was sucked in can that be unblocked or have to be replaced? Wouldnt and error code come up?

[articsteve]

Ok, might as well get this down to the exact details.

You ran out of gas.  I assume you got some in it.  Then it restarted and you drove away.  When exactly during this period did the check engine light come on?  The very moment it stopped?  After you added gas; the moment you got it running? or a few minutes or hours later?

A semi plugged fuel line or incorrect fuel pressure will not throw a code IMO on that vehicle.

I'm asking these very exact questions because running out of gas might have been a red herring. 

You know it would be cheaper for you to buy a fuel pressure gauge and some extra line and get the garage dudes to install it for you so you can watch it yourself.  That's providing you keep focusing on the fuel side of things.

You know that while you drive and the fuel sloshes around the pump itself could be going off and on.  That would not show up when the vehicle was standing still in a garage. 

The only reason I am still stuck to the fuel pressure is that those GM pumps in those 4.3 are total crap and it is very common for them to go out at 80K.  Find a GM 4.3 BBS and you will hear it there. I hear it from my dealer friends and have for years.  Wait till you price one of those integrated fuel pump units. 

It's a tough one.  So it could be a electronic control issue, but I would absolutely rule out the fuel pressure/pump issue first because that is a cheap intervention in comparison.