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94 Sierra Ext Cab Stall at cold start

Razormann

By Razormann
in Ask A GM Technician

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Razormann Enthusiast

Razormann

Posted
Posted

I have a 1994 Sierra with an extended cab 4x4, 350 engine, auto trans, 173K miles everytime I try to start it when the engine is cold it will fire right up and then die. It usually takes a little while to get it started again. Before it dies is does not stammer or surge or sputter or anything, it just shuts off. It has happened to me a few times while driving both at low sppeds and at high speeds. However for the most part once you get it started it runs very well and there are no problems. Here is a list of everything that has been replaced:

Plugs and Wires

Ignition Module

Ignition Coil

Fuel Pump Relay

Coolant Temperature Sensor

All of these items were changed in the last week, Also the fuel pump is less than a year old.

I had it in the shop and they could not find anything, they said my fuel pressure was good. I am kinda stumped on this one, I am testing the MAP sensor today, I was told that if I unplug it and start the truck it will run crappy but if it stays running that is my problem. I have also heard that it could be the Crank Sensor. Is there a test that can be done it it without a meter? Such as unplugging it or anything?

Any help you can offer would be a great help!!!

bobcat5544 Enthusiast

bobcat5544

Posted
Posted

mass air flow sensor won't shut the engine off like you are describing, only part of your system that can shut off then engine like your turned your key off is the ignition system.

 

Things To Check

ignition switch- see if it loses power coming out if it

pcm-check to see if loses power going into it and also check ground

ignition coil- check to see if it loses power to it

distributor- see if it loses power to it

oil pressure sender - look at it see if oil is coming out of it unplug it

 

all of this (exept oil pressire sender) can be checked with a test light any power loss with stop veh from running

ChevyTech007 Enthusiast

ChevyTech007

Posted
Posted

You need to determine if it is a fuel or fire problem. When it dies and won't restart, take the air cleaner off and see if you can see gas spraying from the injectors. That will narrow it down a lot. Also you need to scan for codes.

Razormann Enthusiast

Razormann

Posted
  • Author
Posted
You need to determine if it is a fuel or fire problem. When it dies and won't restart, take the air cleaner off and see if you can see gas spraying from the injectors. That will narrow it down a lot. Also you need to scan for codes.

 

 

 

 

I have fuel coming from the injectors right up to the point when it dies. As far as codes go that will take some doing I have to locate a code reader and do it at a cold start because when I had it in the shop they said they found no codes...

 

Thanks for the help so far!

Razormann Enthusiast

Razormann

Posted
  • Author
Posted
After it dies, how long do you have to crank it to get it started again?

 

 

 

 

If i return the key to the off position it will start on the next crank and then die. It takes anywhere from 2-10 minutes of that before the truck will stay running.

Razormann Enthusiast

Razormann

Posted
  • Author
Posted
come to think of it do you have any alarm system factory/aftermarket on this truck

 

 

 

 

I do not have an alarm but i do have a remote start system. i removed of the the relays that control the remote start in the thought that if it was trying to send conflicting info to the truck it could no longer do so. I am starting to think that it is the Ignition switch, it sounds like a likely culprit based off of what is happening and what I have been hearing. But I would like to be sure before I dig into that project, it seems a little involved.

:banghead:

Razormann Enthusiast

Razormann

Posted
  • Author
Posted
come to think of it do you have any alarm system factory/aftermarket on this truck

 

 

 

 

I do not have an alarm but i do have a remote start system. i removed of the the relays that control the remote start in the thought that if it was trying to send conflicting info to the truck it could no longer do so. I am starting to think that it is the Ignition switch, it sounds like a likely culprit based off of what is happening and what I have been hearing. But I would like to be sure before I dig into that project, it seems a little involved.

:banghead:

 

 

 

 

 

Nope.... not the ignition switch back to te drawing board....

bobcat5544 Enthusiast

bobcat5544

Posted
Posted
Next I would tap test the ECM, also I would monitor fuel pressure when the problem occurs.

 

 

 

 

there is no way fuel pressure, will cuase this veh to just stop running, if you read what he has stated, it just stops, it does not chuggle, spudder, run ruff. it just stops running like when you turn your key off. If it is fuel related it would spudder then quit...

 

the most likly possiblities is ignition switch, pcm/ecu, ignition coil primary or secoundary, distributor, or power/ground wires.

  • 2 weeks later...
Razormann Enthusiast

Razormann

Posted
  • Author
Posted

After some more poking and prodding and testing, the electrical systems was ruled out. I had someone I trust bring over a real diagnostic machine and nothing was found out of whack in the electrial/ignition system. So we decided that it must be a fuel problem as unlikely as it seemed, since it didn't spudder and die or choke out or anything.

Long story short, it was the fuel filter. I changed and the truck has been running great ever since (Knock on wood)

 

It seemed that my fuel pressure was good once it was running but I was having problems with volume so it would get enough to start but not stay running.

 

Thanks to everyone who offered me advice on this subject you all were a great help and i learned some good troubleshooting skills. Hopefully I won't have to use them again anytime soon....

ChevyTech007 Enthusiast

ChevyTech007

Posted
Posted

 

 

there is no way fuel pressure, will cuase this veh to just stop running, if you read what he has stated, it just stops, it does not chuggle, spudder, run ruff. it just stops running like when you turn your key off. If it is fuel related it would spudder then quit...
:cheers::D

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