I have a 2.9 ranger 4x4 1990. The truck drives great 1st through 3rd. But when I shift to 4th gear the truck starts spitting and sputtering and sounding like a mild backfire in exhaust. Especially when approaching a hill... I have the fuel pump on a toggle direct wire to battery. Truck ran perfect after I put on toggle. Until I got on interstate and got up to 80-85 mph. When I got off interstate and accelerated again and made it to 4th gear the spitting and sputtering started and hasn't stopped. I repeat. 1st 2nd and 3rd run fine no problem. Revving engine up while in neutral or clutch engaged it does fine. Please help me figure out why it's doing this.

 

When is the last time you changed your fuel filter ?

 

+1 ^^^

Welcome to the forum

You have a fuel flow issue, you are "running out of gas" on high demand

Why would you add a toggle for fuel pump?
Much easier ways to get power to fuel pump with a jumper wire

And test battery voltage engine off, 12.3v to 12.8volts is OK, under 12.3v is not OK

Then test battery voltage with engine running, 13.5v to 14.5v is OK, under 13.5v is not OK

Fuel pump is an electric motor, so at 12v it spins at XXX RPMs at 14v is spins at XXXX RPMs............. so low volts = low RPMs = low flow

 

I haven't changed fuel filter. I did however take fuel lines loose from engine side and turned on the fuel pump and it had good pressure through fuel filter. Dunno if that makes a difference or not.

 

I added the fuel pump to a toggle because I had wiring issues on pump. And it was only way I knew to fix it. Tried jumper and it fried connector to fuel pump. And burnt up pump...

Advise on how to run jumper properly. I have no clue where short is on original wiring. When I bought truck it had jumper and I hit bump on way home and it died. I figured original wire caught connection and it double fed pump and fired it and connector

 

If fuel pump connector at the tank "fried" then fuel pump was already "burnt up"

I assume you jumpered power to fuel pump without a fuse, which is never a good idea, and what you get is the wire acting as the fuse at the closest point to the "short", wire gets hot and melts, like a fuse does, except wire is not designed for that, a fuse is, so you get a sticky melted mess, lol, live and learn right?

So hopefully you have FUSED power to the fuel pump now, 20amp fuse for fuel pumps, NO bigger, but it also depends on the wire size, if wire size is too small and fuse is to big then the wire becomes the fuse, so gets hot and melts

 

I used #12 stranded wire. My daytime job is an electrical apprentice. A/C . not too knowledgable about D/C
The wire should he protected. I thought about running through a fuse but with wire size I'm not worried about it. I eliminated all factory wires except a ground and my fuel gauge wire. I ran new wires to connector and to switch

 

????

Not sure you understand the reason for a fuse or circuit breaker, these are used regardless of wire size, a fuse prevents a wire or device from "burning up" when there is a short, fuse heats up and separates cutting power, circuit breaker heats up and "trips" cutting power.

When you don't use a fuse they call that building a toaster, lol, because thats what you ultimately have when there is a short, not if, always when

And fuses or circuit breakers are placed as close to the power source as possible/practical
In cars/trucks the engine fuse box has the fuses for the whole vehicle, the cab fuse box is a "sub-panel" running from some 60amp fuses in the engine fuse box
In a house the circuit breakers are at the breaker panel where power comes into the house from the power pole outside

Put a fuse on that wire, sooner than later

 

So I put a fuse on the pump toggle. Now it runs even worse. Dont know why that would change things up because now 1st and 2nd spit and sputter like there is a bad miss. I'm going to change plugs and wires this afternoon hopefully that will straighten it out. Still looking for ideas on where to get a jumper wire to and from. Obviously to the fuel pump.but where do I pull jumper from. Just wanted to say thank you for everyone who has replied and helped me so far. There is still good people out there who will take their time to help a fellow out