Does anyone know what this is ? Truck is shutting off randomly.

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viking2021

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I have an 88 Chevy K2500. Brand new GM Crate motor from GM performace. I have replaced spark plugs,wires, fuel pump, ignition coil, o2 sensor, Throttle body was rebuit, Map sensor, Distributer, TPS, EGR valve and igntiton modual. The reason for this post is the truck is randomly shutting off. At first it would happen once in awhile now it is happening at on every drive. It shuts off like with a snap of a finger almost like someone turned the igntion key to the off postion. Now it is doing it while it is parked at idle. I can usually start it right back up again after i cycle the fuel pump. When it is idleing it runs great. Also this happend last week when i would go to give it any gas it sarted spuddering and choking out but once it went back to idle it idled fine. Am i dealing with a wiring issue from when the engine got put in or could it be a part that needs to be replaced. I was under the truck today and the sensor above the starter feels very loose but i dont know what that is. And the sensor that is on the front axle i don't know what these are at all. Any information is helpful.
 

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HotrodZ06

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I believe the first one is the connector for the front axle actuator, and the second picture i think you are talking abut the knock sensor.
 

454cid

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The one, by the starter is probably the knock sensor.

Check your battery connection, especially if you have a side post battery. Actually remove the bolt and maybe even the rubber covering. They can corrode internally, which won't be visible when assembled. I'm not sure about the TBI engines, but a momentary disruption of a battery connection will shut the engine off on my Vortec. I had a bad connection and a leaking battery with acid flowing down the positive cable to the starter.

The engine shutting off happened to me several times before I fixed it. Sometimes it would start back up, and sometimes I'd have to wiggle the positive wire.
 

thx1138v2

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I have a 94 GMC Sierra C1500 4.3L that I was driving about 65 MPH on I-10 in San Antonio when it died in the same way- it just shut down like someone turned the key off. My problem was the fuel pump. I rolled it into a mechanic's shop, they replaced the fuel pump, and it fired right up after that.
 

DeCaff2007

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You check the ground on the fuel pump? It's bolted right to the drivers side frame rail, near the pump. It's also an area prone to rust, and that little 18 gauge wire won't last long in any rust belt.
 

Schurkey

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What is the fuel pressure when the engine stalls?

Connect a scan tool, verify all sensors. Check for "codes", but more important--see what happens to sensor data just before the engine stalls.

When my '88 stalled randomly and wouldn't re-start, it was the magnet on the distributor shaft near the pickup coil. But you've already replaced the distributor.
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