88 landcruiser: fuel pump works, I've pulled it out and tested it, but I only get gas when parked down hill. I've checked the wiring from the relay to the pump.

c1500 pickup 5.7l motor only has 38,000 miles 88 and chev.
is this the MPI (8 injector ) or that funky throttle body injector fuel system. a photo of it would be nice.
7.4vdc that is dead to rights dead wrong too low.
at idle I guess you never said tests conditions were
the battery voltage at idle must be 13 to 15vdc
if not the alternator is dead or fuse blown or offline .(ask)
so 13vdc at the battery may be 12vdc at the pump
a 1 volt ,voltage drop on the 2 pump wires max, (5amps flowing or so)
so is bad wiring /connections to the pump, is not good ever.
so you THREW a ton parts guessing wrong, why do that.use tools to find, ,and tool #1 is and OBD2 scan tool (real not silly $17 code readers ever)
I think you do not understand the FPR.
if the pump is weak, and sure is , (it alone) then the FPR is running at its max setting, (dynamic it is) and at the limit of the FPR as you say ,try to fly up a hill with with 2000 lbs of bricks in the back( design limits)
the FPR must open fully to do that act (more fuel flows)
but it CAN not do that with it already at max. at idle
see?

7.4vdc at idle is wrong and at crank time, 10vdc to pump can be.
cranking drops 1 or 2 volts, at battery direct.

16guage pump wire is about 0.6vdc drop per wire max.
so 2x that, Plus wire and ground.
is 1.2vdc,or about 1vdc max.
so 13v minus 1 v = 12 vdc to pump at idle'
ohms law and wire gauge 16 at 20feet. long.
pure math, E = I x R.
The resistance will be 0.08 ohms. good wire and good connectors
0.5v drop at 6 amps.
some pump fail hard, (all?) and draw huge currents even over 15amps. we use a scope on all suspected pumps to see them fail early (PSI be danged)

see the pump mess up, so have commutator drop outs
others have 1 segment coil shorted and currents go crazy high.

Duane here has like 10 videos on wild pumps, endless topic.


http://www.realfixesrealfast.com/realfixesrealfast.com/Postal_L_L_V_Videos/Pages/LLV_Fuel_pump_drops_out.html

a FPR can not hide a bad pump. or bad wires to it.
we test ALL That or go broke guessing,
ask for tests, and you did and I answered

The first thing I would check is the park brakes coming fully off when released. If the units are rusted and stiff you will have dragging brakes which will give the symptoms you describe. After all it has been sitting for a year with the park brake on.

yes try getting the fuel pump pressure tested by a mechanic. the other thing it can be is the injectors are plugged try running some lucas fuel system cleaner.

As you have probably figured out by now, you will have to treat it as a no start and troubleshoot it when it fails to start. Until you figure out if you are loosing spark or fuel to the injectors when the engine dies you have no direction to go in.

get a test lite and pull ur relay out and test it if its not lighting up then check your fuel pump

You will need to check the engine control computer for fault codes. To do this fiollow the instructions at this LINK.

What is the fuel pressure reading now? Has the distributor ignition rotor ever been replaced? They burn through and cause all kinds of problems. Also this could be spark plug wires leaking or shorting out to the engine block. I would take a very close look at the ignition systems condition.

My first thought is that you have wires shorting out somewhere, probably right above the gas tank. Either way, you're going to have to pull the gas tank off to find it. Usually, when a fuel pump dies, it just doesn't work, and won't normally blow a fuse. Pull the tank down, inspect the wiring, and change the fuel pump if the wires check out okay.

Try changing your engine temp sensor, it won't triger a fault code but sets ecu to a defalt setting of -20 or 200 degrees, causing an over fuel situation. Not a garanteed fix but for under $20 it is worth a shot.

check youre catalatic converter it maybe stopped up.....