Welcome to TRS
Not an easy question to answer.
To start you will need a new battery.
Then siphon out as much gas as possible, then remove fuel filter(in frame under drivers seat) put a larger bowl/bucket under the gas line coming from the tank.
Turn key on and the last of the gas should squirt out as fuel pump turns on, it should continue to siphon out until take is drained, if not cycle key off and on, fuel pump only runs for 2 seconds at a time.
Once gas stops coming out put in 5 gallons of fresh gas, install new fuel filter.
Also add 1/3 can of Seafoam to the gas, or similar injector cleaner.
Why has it been sitting for 6+ years????
Most people don't park a working pickup truck for 6 years unless there was a problem that made it undriveable.
Do you know what that problem was?
The M5OD-R1 manual transmission is fairly bulletproof, it uses ATF, yes automatic transmission fluid, you should drain it and refill with new fluid.
Check the drained fluid for metal.
4.0l OHV is a very reliable engine but would crack a head if ever overheated.
You can check for that by doing the Glove Test.
Glove Test is free and definitive test for cylinder leak.
Cold engine
Disable spark, unplug coil pack, you want a no start
Remove rad cap
Remove overflow hose and plug that port on rad
Coolant level can be at the top but an inch or so down is better.
Put a Latex Glove over rad cap opening and seal it with rubber band.
You can use a balloon instead or even a condom, lol.
Crank engine and watch glove
If glove starts to pulse up and down then you have a cylinder leak, each time that cylinder is on it's compression stroke glove will bounce up.
If glove just lays there then you don't
If glove is bouncing then you can remove 1 spark plug at a time and crank engine again.
When glove stops bouncing then the last spark plug pulled out was from the leaking cylinder, put spark plug back in to confirm.
While this information is not required it can be helpful after disassembly to pin point the leak, i.e. gasket or cracked head.
After the Glove test and no sign of cylinder leaks, drain the oil, change oil filter, and add fresh oil.
Pull out all 6 spark plugs, replace or clean them and gap them, .054"
With spark plugs out and new oil in, crank engine over, this will pump the new oil through the bearings pushing out and older oil.
Crank it 4 times, counting to 5 each time.
This will also pump the new fuel into the injectors.
Some of the injectors may be clogged with dried out gasoline residue, but may not, so you cross that bridge when you come to it.
Put in spark plugs and then try to start engine.
Listen for noises after start up, look for coolant leaks
You will need to change the coolant but run engine a few days to see if there are leaks that need repair before changing coolant.
4.0l OHV rebuild kit with new pistons runs about $550
Set of heads runs $450-$550
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