I have an 85 k10 silverado 4.3l 305 that cuts off once in a blue moon when going down the highway. We have replaced spark plugs and typical maintenance stuff. Doubt it is the fuel pump since it usually cranks back up and I can drive it for a while before it might shut off again. I have read somewhere that it may be the ignition switch, not sure if the vehicle has an ignition control module because I couldn't find it in the manual. Any suggestions would be appreciated. Thanks
Starting at the beginning of your story, you listed both the V6 and V8 engines. Either way, they are both carb models so no fuel injection and no electric fuel pump.
There is a pickup coil and a spark module inside the distributor that could be the problem, as well as the coil and other components.
It will be very tough to troubleshoot if it always starts back up.
It the problem was the key switch you would loose warning lights on the dash too.
SOURCE: 2001 GMC Sonoma Engine stopped while driving
sounds like it could be plugged injectors or a timing problem.
SOURCE: Distributor wont spark
check the fuseble link.
you can measure it, and make sure the contact are clean and secured.
the other thing is the check the ignition switch, make sure you have 12v going to the switch.
check thermo switch on top of the block.
SOURCE: truck cuts off while driving down the road.
Replace the TFI module. Ford back in 1986 thur 1993 had problems like the one you wrote about. TFI module gets hot and shuts car or truck off then when it cools sometmies starts and sometimes not.
SOURCE: "Cranks, but won't start". Replaced fuel pump, CKP, ICM & nothing
If the engine
cranks over normally when you attempt to start you car, but the engine
does not start, the problem may be NO FUEL, NO SPARK or NO COMPRESSION.
The engine needs adequate fuel pressure, a properly timed spark and
normal compression to start.
1) To find why the engine won't
start, remove the air inlet tube from the throttle body, push the
throttle open and spray a small amount of aerosol starting fluid into
the engine. Crank the engine. If it has spark and compression but NO
FUEL, it will start and run a few seconds before dying. If it does NOT
start, it probably has NO SPARK.
2)Another method to check for spark is to pull a spark plug wire
off of a spark plug (if it has plug wires, coil-on-plug ignitions do
not) and place the open end of the plug wire near a metal surface on
the engine. Have a helper crank the engine while you watch for a spark.
DO NOT hold the wire while doing this as it can shock you. If you see a
spark, the problem is not spark, but most likely NO FUEL or NO
COMPRESSION. If you do not see a spark, the problem is in the IGNITION
CIRCUIT.
3)Proper fuel pressure is critical for fuel injected engines
to start and run. You should hear the fuel pump inside the fuel tank
buzz for a couple of seconds when the ignition is turned on (no buzz
means the pump is not running and the engine is not getting fuel). You
can smell the tailpipe for gasoline vapors after cranking the engine.
If you smell gas, the problem is likely not fuel but NO SPARK. You can
also remove the plastic cap and press the schraeder valve test fitting
on the fuel rail to see if there is any fuel pressure to the engine
(not a very accurate test because fuel pressure must be at a certain
level for the engine to start, for that you need a gauge). Even so, no
fuel at the fuel rail would tell you fuel is not getting to the engine..
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Sorry, meant 5.0 liter, the vehicle only cuts off when it is warm when driving, sometimes the vehicle seems to hesitate when cold or warm when stepping on the accelerator. Unfortunately from a troubleshooting standpoint, the vehicle always starts back up and runs fine for a while. We had the leaky vacuum lines replaced also.
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