I have 94 ranger 4.0 auto. Sometimes it runs great sometimes not.Have replaced fuel pump,fuel filter, MAF ,and throttle pos sensor. When it acts up like someone turning off ign abot 2 or 3 sec, then will pick back up then same thing again .sometimes runs great no prob. Whats up Guys ??????

 

Welcome to the forum

Not alot to go on

Does it happen only after warm up, or any time, cold or warm?

You have changed the fuel pump.
So when it loses power it must feel like it is running out of gas, or was that unrelated to current symptom?

When you turn on the key does the Check Engine Light(CEL) come on?
And then go off after start up.

The CEL doesn't automatically come on when there are codes in memory, many codes are background codes that don't require immediate attention.
Because the power loss is so short the Computer(PCM) may consider it a non-issue, a back ground code is set but PCM doesn't turn on the CEL

If CEL is working then I would see if there are any codes in memory
Next to engine fuse box, firewall side, you will find the VIP(OBD) connector

Picture here: Ford Ranger - Testing EEC-IV Equipped Engines

Key OFF
Put a jumper wire between Self-Test IN and SIG-RTN
Get in the truck with paper and pencil
Turn on the key
Watch CEL, it will flash the codes in memory

1994 uses 3-digit codes, seen here: OBD-I Diagnostic Trouble Code (DTC) Applications - Ford 3-Digit Codes

1 flash and pause = 1
2 flashes and pause = 2
ect...
So count the flashes and write them down, they will always be 3-digits, and no 0's, lol

There is a longer pause between each 3-digit code

You can turn the key off and then on to restart reading the codes again to double check or if you missed something, doesn't hurt anything

If you want to clear the codes, turn on the key and wait for codes to start flashing
Get out of truck and pull out the Jumper wire while codes are being flashed, that tells computer to clear memory
Turn off the key, next restart may have wandering idle as computer relearns IAC Valve settings.

Checking the codes to see if PCM is "seeing" a temporary power loss at injectors, coil, or fuel pump, it monitors all those systems

And how does the ignition key "feel" when you turn it to RUN or START, does it seem to be loose or tight?
The ignition switch itself is under the steering column, the key pushes and pulls a bar that slides ignition switch into its various positions, and they can wear out.
When you lose power does radio go off or any other electrics?

 

I have had the truck bout 1 1/2 yrs had no prob bout running except last year fuel pump was gettin hot and shutting engine .the prob was the fuel pump was cracked and rusty.replaced pump ran great the fuel went out again.like i said new pump,fuel filter tps throttle pos sensor.was gonna take it to garage and put in on a machine ,it ran like acaulded dog for several miles,next day i started to town it acted up again like it's running out of gas u can let off gas pedal it will pick back for a 2 or 3 seconds then cut out again.got to soft pedal it to get it back home

Would pull out my hair but don't have any to spare LOL

 

the C E L has never come till i started having the prob, now it comes on while driving and goes off the later comes back on off and on not repeatly but often

 

Is the new fuel pump a Motorcraft/Ford OEM?

People have had issues in the first few years with non-Ford fuel pumps, they are much cheaper, and worth it if they last.

Read the CODES, easy to do, if CEL came on then there, for sure, are codes to get

 

no it's off brand. i had o'relly's put on a hand helt dia sys showed nothing wrong.

 

Have to do the Flashing CEL as described above

o'relly's, and most other's, OBD readers won't read Ford codes reliably
So they said it gave them 111 code, with no history codes?
That would be very odd since you said CEL did come on and go off while driving
And could indicate computer problem

Do current shutdowns match past shutdowns when fuel pump failed?

There are only a few things that can shut engine off while driving
Drop in fuel pressure, fuel pump shutting off
Loss of Crank position signal, no spark

On the front passenger side of the engine toward the bottom is the CKP(crank position) sensor.
It "reads" a tone wheel(looks like a gear) on the backside of the crank pulley
The CKP wire runs up past water pump and thermostat housing where it joins the main engine wiring harness.
CKP sensors rarely fail, not never, but rarely, and when they do it is total failure, no start, no run
But wiring is a different story

This loss of signal would FOR SURE cause a code


If you want to replace something on spec, then Fuel Pump Relay in engine fuse box would be it.
If you have AC then you can just swap WOT relay and Fuel Pump Relay, same relays, or you can buy a new one, $4-$6, just a standard 12v/40amp automotive relay, nothing special

 

after church i hooked up volt meter the way it is shown. got a code i thought was 115 the codes dosent show 115 .it was 125 code which was low voltage @ tps throttle pos sen. the brown with white tracer wire only had 5 volts. no voltage on the other 2 wires key on ,checked wiring diagram in book that wire goes to P C M . that is far as i could trace it .is the P C M bad ? Still fishin for the answer to fix it.

 

You don't need the volt meter to get the codes on a '94, just install the jumper wire, turn on the key and count the flashing CEL, 3 digits in each set, super easy

TPS needs to be tested while it is connected and with key on engine off
Use a sewing needle to pierce the wires
It gets 5volts from computer on the top wire.
Center wire should show under 1volt when throttle is closed, .69-.99volts
then go up slowly to 4.5-4.9volts when throttle gets to Wide Open


MAF sensor, Coolant Temp sensor, air temp sensor all share that same 5volts from the computer