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Q: Sudden Loss of Power at Highway Speeds on 1990 Toyota Pickup


1990 TOY P/U, v6 158K miles

i'm having an intermittent problem where i am cruising at 55-70 mph, either in 4 or 5th gear and i suddenly have a complete loss of power, the truck bucks slower when this happens, if i push the accel nothing, but, if i wait a few seconds i'll get power back. i've only seen this at highway speeds. i'm lost, any thoughts?
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It hard to comment without experiencing the problem first hand, but I would "Tee" in a fuel pressure gauge into the fuel rail and monitor fuel pressure and fuel volume. Note fuel pressure when the truck is running well and when it falters, by taping it to the windscreen where you can see the gauge during your test drive. Replace the fuel filter, under the truck in the middle under the passenger side, see if the fuel coming out is dirty during the changing of the filter. Check the distributor cap and rotor and condition of the spark plug wires.

thanks for the response.

now the engine light is turning on. i did the diag code and it was 42, which is supposed to be the vehicle speed sensor.

i suppose if this sensor is not functioning properly it could be thinking the engine is in a serious over speed condition and cutting fuel supply? does anyone know if this is a possibility?

also, does anyone know the location of the VSS? is it someplace i can get to when i'm on my back under the truck? or should i just take it to the dealer?

anyone have a link for a 1990 toyota 4WD PU service manual? (i have them, but they are in alaska and i am in florida....)

I'm having this exact same problem! Did you ever find out exactly what it was? I've been to mechanics all over town but they all seem to have different ideas of what it could be. I've changed the fuel filter, fuel looked like it may have had a little bit of a brown color to it.
Residue in the fuel tank was the issue that was causing the problem for me. I cleaned out the tank, changed the fuel strainer on the fuel pump to resolve the problem. Careful when removing the fuel pump for the plastic coating on the wires are brittle. I applied liquid plastic on the top of the fuel pump connector for the wire coating was splitting.
Two words: Spark Plugs. It was not on the top of my list of possiblities. Old spark plugs cause the symptoms you are facing. As a side note, the Camry puts them in such a spot that it requires taking off parts. I would highly recommend having it done by a mechanic and let them sweat it out.

- Yorkman
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