87 hilux pickup fuel guage problem

Sure sounds like a dead gauge sender to me, especially if the gauge "comes back to life" consistently every time the tank reaches that 'almost full' level. Time to clean out the bed and see if you have an access hatch to get to the top of the fuel tank, otherwise it's fuel tank dropping time.

(It could be a loose connection at the tank or a bad gauge if it was just plain dead always, at any level. The "works at 3/4" eliminates that possibility.)

Standard disclaimer: Have the fuel tank nearly empty, do the work outdoors with a breeze (not in a sealed up garage with the door down), lots of fire extinguishers on hand, No Smoking, Sparks, Ignition Sources Or Open Flames within at least 50 feet, and remember that gasoline fumes are the dangerous part.

If there were no fumes present, you could put a match out in a pool of liquid gasoline - it's the gasoline vapors mixed with atmospheric oxygen anywhere between the (rather wide) upper and lower explosive limits that can go BOOM!! on you.

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