Stalling 1990 sierra

[Ceseus]

I bought this nice step side sierra with 350 v8 and 146k on the odo. When I start it, it turns right over but dies if I give it gas, or even on it's own. Sometimes it starts with "service engine soon", I hear popping in the muffler, but then it stays running and runs good, but muffler popping continues... i replaced the fuel filter, but it hasn't changed anything naturally. plz help me out.

 

[Jared Jackson]

My first instinct says MAP sensor or a Throttle position sensor. I say that as just my instinct from past experiences. You need to start troubleshooting stuff to narrow it down. Have you checked for any vacuum leaks? Look at your intake manifold and follow any vacuum hoses that go to it. I don't think a clogged PCV valve would cause the engine to die when given gas, but go ahead and check that as well as it is commonly overlooked anyway. I assume your air filter is clean? Have you checked fuel pressure? I have heard of pumps that are weak enough to maintain an idle but fail to deliver enough fuel under a load. I have always just had them die, but fuel pressure is a good check regardless!

 

[Jack Schneider]

Sounds like a misfire if it’s popping. Throw in some plugs and wires

 

[Urambo Tauro]

...Sometimes it starts with "service engine soon"...

Did you pull codes yet?

 

[Ceseus]

Not yet. Got to drive it to a shop that can plug in obd1

 

[Ceseus]

Sounds like a misfire if it’s popping. Throw in some plugs and wires

Sounds like a misfire if it’s popping. Throw in some plugs and wires

It feels more like it's running rich

 

[Ceseus]

My first instinct says MAP sensor or a Throttle position sensor. I say that as just my instinct from past experiences. You need to start troubleshooting stuff to narrow it down. Have you checked for any vacuum leaks? Look at your intake manifold and follow any vacuum hoses that go to it. I don't think a clogged PCV valve would cause the engine to die when given gas, but go ahead and check that as well as it is commonly overlooked anyway. I assume your air filter is clean? Have you checked fuel pressure? I have heard of pumps that are weak enough to maintain an idle but fail to deliver enough fuel under a load. I have always just had them die, but fuel pressure is a good check regardless!

I will order those, replace and see what happens. This weekend.

 

[Jared Jackson]

I will order those, replace and see what happens. This weekend.

I hope that fixes the issue! I just threw out some parts that I have seen relate to the symptoms you described. I just don't want you to spend your money throwing parts at it if other things were obviously issues.

 

[Schurkey]

Diagnose before replacing parts. Costs less in the long run (Usually).

At least inspect the old parts before throwing them in the dumpster.

 

[ram1220]

I had this in my 90 Sierra 5.7l about a year ago. Turns out the distributor cap was bad.