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1990 chev silverado stalls then won't start

jacksZ71

By jacksZ71
in Ask A GM Technician

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jacksZ71 Enthusiast

jacksZ71

Posted
Posted

As above I have a 1990 Chev 1/2 ton Z71 350, with 300,00 klm's on it, first some histoy, about a year a go I had a similar problem after checking for spark their was none for which I replaced the Ignition coil, pickup coil and modual. last week it had what appearded to be the same problem. When the truck warms up it dies then wouldn't start. When the engine sits 8 or more hrs it will restart, I checked out all the same parts and all check OK. I checked for spark and there seems to be lots, then I tried adding a small amount of fuel in the carb, it starts runs a while then stalls won't restart unless I again add fuel first. any thoughts.

:P

bobcat5544 Enthusiast

bobcat5544

Posted
Posted

It's obvious you have a fuel problem.

Get the truck warmed up so it stalls out. Once you have it where it won’t restart. Turn the key to the on position and listen for the fuel pump to kick on.

Can you hear it kick on?

 

If yes then remove the air cleaner look at the fuel injectors have someone turn the key on do see the injector squirt fuel.

jacksZ71 Enthusiast

jacksZ71

Posted
  • Author
Posted
As above I have a 1990 Chev 1/2 ton Z71 350, with 300,00 klm's on it, first some histoy, about a year a go I had a similar problem after checking for spark their was none for which I replaced the Ignition coil, pickup coil and modual. last week it had what appearded to be the same problem. When the truck warms up it dies then wouldn't start. When the engine sits 8 or more hrs it will restart, I checked out all the same parts and all check OK. I checked for spark and there seems to be lots, then I tried adding a small amount of fuel in the carb, it starts runs a while then stalls won't restart unless I again add fuel first. any thoughts.

:banghead:

 

 

 

jacksZ71 Enthusiast

jacksZ71

Posted
  • Author
Posted

Thanks

I checked the fuel pump I have 11lbs pressure I checked the flow I have 4litres /3.8US quarts per minute flow.

I put in a new gas filter on.

After it is warm and stalls there is know fuel from the injectors when you try to start it, however if you add a little fuel directly to the throttle body it fires up and continues to run for a while then loopes and stalls again you can repeat this over and over. By looping I mean it almost dies then speeds up again except when it stalls.

chevroletmb Enthusiast

chevroletmb

Posted
Posted

hmm it's a long shot but some older vehicles used oil pressure switch to send power to the fuel pump as a backup for the furl pump relay.

so if you have a bad relay, adding fuel to get it to start may trip the oil

pressure switch to kick in the fuel pump doesn't really explain the stall but a

tbi should have more than 11lbs fuel pressure.

SPARK CHASER Enthusiast

SPARK CHASER

Posted
Posted

You might try checking the coolant temperature sensor and/or wiring between the ECM and the sensor. You should have about 5 volts in the wiring from the ecm with the ignition on. The sensor itself should have about 2700 ohms resistance at room temperature and about 240 ohms at operating temperature

jacksZ71 Enthusiast

jacksZ71

Posted
  • Author
Posted
hmm it's a long shot but some older vehicles used oil pressure switch to send power to the fuel pump as a backup for the furl pump relay.

so if you have a bad relay, adding fuel to get it to start may trip the oil

pressure switch to kick in the fuel pump doesn't really explain the stall but a

tbi should have more than 11lbs fuel pressure.

 

 

 

 

 

I recently changed the oil pump nad when the engine is cold I show off the gauge pressure then after it warms up it drops down to around 250 would two high a pressure cause the system to shut down?

I'll check out the oil pressure gauge for problems

Thanks

jacksZ71 Enthusiast

jacksZ71

Posted
  • Author
Posted
You might try checking the coolant temperature sensor and/or wiring between the ECM and the sensor.  You should have about 5 volts in the wiring from the ecm with the ignition on.  The sensor itself should have about 2700 ohms resistance at room temperature and about 240 ohms at operating temperature

 

 

 

 

Thanks

I'm willing to try just about anything, I have a new twist to the delema after the engine starts to warm up if I turn it off before it stalls it still won't start without adding the gas to the TBI.

Jack

jacksZ71 Enthusiast

jacksZ71

Posted
  • Author
Posted

THANKS!!! :gmc:

?

I found the problem

After all you who helped first thanks for taking the time. I checked a and rechecked sensors, fuel

pressure, lines, etc. although things seemed OK during the test, it still won't continue to run. I

purchased a new fuel pressure gauge and found I had 15lbs pressure, 9-13 is normal, still it would

not keep running. I replaced the fuel pump, no difference something was shutting of the fuel. I

checked oil & Coolant sensors OK I checked for vacuum leaks found two small ones, I could see

a difference, removed the EGR valve and cleaned it, run a little better, removed and cleaned the

idle mixing valve, truck running better, replaced the throttle positioning sensor truck runs smooth

still dies. only thing left was to check the wiring system,

the fuse for the injectors was loose can you believe it After all that just a fuse. Well I say that

however the vacuum leaks and the TPS were causing the rough idle, the fuse just caused me to fix

them. Thanks again for everyone’s help and suggestions

:cool:

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