Stalling issue

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BrockGrimes

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I have a 1988 C1500 with a 350, automatic.
I have to turn the key a couple times to get it started. Recently it started doing this thing where it runs fine but will sometimes stall when i put it in gear, drive or reverse.
If I start it and it idles for a few min sometimes it'll stumble and stall. If I drive it it runs fine but sometimes will be hard to start after being driven, seems to be getting worse.
The engine has low miles like 50k, most of the sensors are newer, the dist and coil are MSD.
I tested the fuel pressure at the throttle body and it's a constant 13 while running.
Tested before the fuel filter and it's 14. With it before the filter I notice when I turn on the key it builds pressure but almost immediately bleeds off.
Was going to cap it (deadhead) and see if it held pressure but didn't have a cap to fit the adapter.

Any ideas, I know this is a common problem but I never see a definitive solution it's always something different it seems.
Most common seems to be a fuel pump or distributor. But i've also seen it be an EGR issue.
 

PlayingWithTBI

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I notice when I turn on the key it builds pressure but almost immediately bleeds off.
That's normal, when you turn KOEO (Key On Engine Off) the pump will prime for 2 seconds, then shut off.

I tested the fuel pressure at the throttle body and it's a constant 13 while running.
If it maintains 13 PSI, odds are it's not you fuel pump or filter.

most of the sensors are newer, the dist and coil are MSD.
Are they quality sensors? MSD has a bad reputation working with TBI systems.

What about your IAC? Is it working properly? You can put it on a scanner and it will tell you commanded steps but, will not tell you if the IAC is actually moving those steps. The scanner may point you in the right direction though.

Maybe clean and rebuild the Throttle Body?
 

BrockGrimes

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AC delco for the MAP ,TPS, and Genuine GM for the IAC just to be sure since it's easy and relatively inexpensive.
Was running and driving fine then it started the stalling thing when put in gear, then it degraded to sometimes stalling or idling off when in park.
To now it's hard to restart after a drive for a few miles, acts like it's trying to start/fire then it finally will and will run fine. Has me stumped.
 

Schurkey

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I have a 1988 C1500 with a 350, automatic.
Same year and engine/computer system as my '88 K1500.

I have to turn the key a couple times to get it started.
Engine cranks, but doesn't start and run? Or engine doesn't crank unless you turn the key several times?

Recently it started doing this thing where it runs fine but will sometimes stall when i put it in gear, drive or reverse.
If I start it and it idles for a few min sometimes it'll stumble and stall. If I drive it it runs fine but sometimes will be hard to start after being driven, seems to be getting worse.
The engine has low miles like 50k, most of the sensors are newer, the dist and coil are MSD.
I wouldn't walk across the street to get a new MSD TBI distributor cap and/or ignition coil, if they were giving them away for free. Communist Chinese junk. The popular MSD coils are known for a high failure rate ever since they moved production to Mexico--and the Chinese ones are even worse.

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I don't know about the MSD distributor. I use Genuine GM distributor housings, with new/fresh main shafts and pickup coils installed into them.

I tested the fuel pressure at the throttle body and it's a constant 13 while running.
Tested before the fuel filter and it's 14. With it before the filter I notice when I turn on the key it builds pressure but almost immediately bleeds off.
Was going to cap it (deadhead) and see if it held pressure but didn't have a cap to fit the adapter.
Sounds like the fuel pump is priming like it should. TBI engines don't retain pressure like the port injection systems do.

i've also seen it be an EGR issue.
Worth checking. If the valve is stuck open, you sure could have stalling/surging especially at low throttle openings, and hard starting.

Was running and driving fine then it started the stalling thing when put in gear, then it degraded to sometimes stalling or idling off when in park.
To now it's hard to restart after a drive for a few miles, acts like it's trying to start/fire then it finally will and will run fine. Has me stumped.
Sounds somewhat similar to my K1500 when the magnet on the distributor mainshaft cracked and became weak. But mine was more of a random misfire until it got so bad that it started stalling and then wouldn't re-start.

You've verified fuel pressure, now connect a scan tool and verify ALL the sensors and computer outputs.

How old are the usual "tune-up" parts--plug wires, plugs, air filter, etc? Will the coil throw a spark that jumps the gap of a dedicated HEI spark-tester? Is the ignition base timing correct?
 

df2x4

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Have you checked for vacuum leaks? Kind of doubt it's your issue considering the hard hot restarts, but it wouldn't hurt to check.
 

BrockGrimes

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First start of the day I have to turn the key a couple time to get it to start. Spins over fine but it takes 2 or 3 cranks before it fires up and it idles just fine.
Sometimes I can put it in gear and drive away. Some days I put it in gear and it stalls and to get it to go I basically have to put it in gear and immediately hit the gas.
If it was a torque converter or brake/vacuum issue it'd do it every time. I suspect the dist. since everything is new or fairly new, like I said the motor only has like 50k miles on it.
The old man I bought the truck from was an old mechanic who restored cars, etc. and took immaculate care of his vehicles. Main reason I bought it a couple years ago.
This problem seems to be a thing with these trucks judging by a quick search but it's rarely solved or at least fix posted/updated.
 

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Connect a scan tool, verify that the IAC works, and the TPS signal isn't screwy. While the scan tool is connected, verify ALL the sensors and computer outputs.

How old are the usual "tune-up" parts--plug wires, plugs, air filter, etc? Will the coil throw a spark that jumps the gap of a dedicated HEI spark-tester? Is the ignition base timing correct?
 

BrockGrimes

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Everything is fairly new or new. The truck will idle and run down the road like nothing is wrong until it stalls out or does the stall when placed in gear thing.
Or hard start after a drive. I was hoping for a bad fuel pump but that didn't pan out. I replaced the coil and no change. I may have to bite the bullet and let a local shop scan it and see what they turn up.
I just hate spending money to let other people touch my vehicle.
 

Erik the Awful

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If you still have a side post battery, check your battery terminals to ensure they're tight. The have a tendency to come loose and cause stalling/hard starting.
 

HotWheelsBurban

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If you still have a side post battery, check your battery terminals to ensure they're tight. The have a tendency to come loose and cause stalling/hard starting.
2X!!! I've gotten caught by this on both trucks. The cable, particularly the stacked positive cables, can feel tight when you touch it, and then if you move it another direction it comes loose.
 
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