The shutdown is likely caused by a critical system failure, and pushing the truck to that speed risks catastrophic engine or transmission damage.
Here's a breakdown of potential causes and the proper steps to take:
Possible Causes (requiring professional diagnosis):
* Fuel System: A fuel pump failing under high load is a strong possibility. The pump might be weakening with age or might have a pressure regulator issue. Fuel starvation at high RPM is a common cause of engine shutdown.
* Ignition System: Problems with the ignition coil, distributor cap, rotor, or wires could lead to misfires that worsen at high speed, potentially causing a shutdown. Again, the age of the components is a factor.
* Cooling System: Overheating at high speed is possible, although less likely to cause an immediate shutdown unless it triggers a safety shutdown system. Check coolant level and look for leaks.
* Electrical System: A failing alternator might not be producing enough power under high load, leading to a power drain and shutdown. Also, check the battery's condition. Wiring issues, corroded connections, or a failing PCM (Powertrain Control Module) could also play a role.
* Transmission: While less likely to directly cause an engine shutdown, a failing transmission could cause a sudden loss of power, mimicking a shutdown.
* Air Intake Restriction: Though unlikely to cause a complete shutdown, a severe restriction could starve the engine of air at high speed, leading to performance issues.
What to Do:
1. Stop driving the truck immediately. Attempting to diagnose or fix this while driving at high speeds is incredibly dangerous.
2. Have the truck towed to a qualified mechanic. Explain the problem in detail.
3. Do NOT attempt to "fix" it yourself unless you have extensive experience with automotive mechanics. This is beyond a simple DIY fix and requires professional diagnostic tools.
4. Prioritize safety. The underlying issue could lead to a dangerous situation if ignored.
Ignoring this problem could lead to further damage, leaving you stranded or causing an accident. Professional diagnosis and repair are essential. Trying to "fix" this at high speed is extremely dangerous and could have deadly consequences.
