Possible electrical problem?

[Ihavearanger]

Hey guys, sorry if this is the wrong place for this. I just bought a 1993 Ranger Splash 4.0 auto 2wd. I can drive it back and forth to work every day, which is 30 minutes 1 way. However, if I try to drive 45 minutes or more, the truck will die and then when I crank it up, it'll idle like poo, and if I give it any gas, it does almost immediately. I was wondering if anyone had any idea what this could be? The guy I bought it from says it's something in the wiring harness, but I've looked all over for a new wiring harness, so if anyone knows where I could get a new one, lemme know. Thanks in advance.

 

[RonD]

Welcome to TRS

I reads like fuel pressure issue.

Does the fuel level in the tank matter?

I would spend the $10 and install a new fuel filter, in the frame rail under drivers seat, if it hasn't been changed.

There is a longshot chance that the EVAP system(sucks air out of fuel tank) is causing too much negative pressure in the tank, so after the 30 minutes of driving the fuel pump can't pump as much fuel out so less and less pressure at the injectors until engine dies.
Loosen gas cap, so tank is not sealed, air tight, and drive it that way, for 45min.
You should get a CEL(check engine light) with gas cap loose, that would be correct response from computer if EVAP system is working as it should.

 

[Ihavearanger]

Welcome to TRS

I reads like fuel pressure issue.

Does the fuel level in the tank matter?

I would spend the $10 and install a new fuel filter, in the frame rail under drivers seat, if it hasn't been changed.

There is a longshot chance that the EVAP system(sucks air out of fuel tank) is causing too much negative pressure in the tank, so after the 30 minutes of driving the fuel pump can't pump as much fuel out so less and less pressure at the injectors until engine dies.
Loosen gas cap, so tank is not sealed, air tight, and drive it that way, for 45min.
You should get a CEL(check engine light) with gas cap loose, that would be correct response from computer if EVAP system is working as it should.

Thanks for the welcome!
The fuel level doesn't matter, it's done it with a full tank, and a quarter tank.
The fuel filter is brand new, and so is the pump.
I'll give the gas cap trick a try when I leave work today. Thanks for the advice!

 

[RonD]

One other thing I would do, test fuel pressure after engine dies, but the easy way.

On the fuel rail, where injectors attach, you will see a Schrader valve, looks like a tire's air valve because that is what it is, will usually have a cap on it just like a tire valve's cap.
Often on passenger side.

After starting engine cold, shut engine off.
Pop hood and remove cap on schrader valve.
Have a towel handy, press on center pin, just like letting air out of a tire.
There should be 35psi of pressure in there so it can squirt quite far, so be careful.
This will give you an idea of what normal pressure should be.

If you have a pressure gauge then even better, test pressure.

After driving and engine stalls do the same test BEFORE trying to restart, but be very very careful as exhaust will be HOT and you do not want gas to get on HOT exhaust pipes.