Hi
i have 94 Ranger 3.0 2WD. Having crank no start issues. Does fire occasionally and will run until applying throttle and will sputter and die. Only significant cost is 542. Have put a new pump in and did get 12 volts at pump with key on. Relay tested and on and tried a different relay to no avail. Checked interia switch and that is good. Replaced fuel pump, PCM, PCV value. Took to shop and was told PCM but apparently was not the issue. Looking for any thoughts before loading with tannerite.

 

That appears to be a fuel pump circuit code. I would think one should look at a diagram of the pump circuit and determine how the computer controls the pump. Typically it turns the pump on a couple seconds when the key is turned to run, and again when the engine starts. I'm not sure if yours switches the positive or the ground. If you can determine where the ground terminal is, cleaning it might solve the circuit problem.

 

Welcome to the forum

What about the fuel filter?

Always good to post the definition with the code since no one has them all memorized, lol
And also see if we are on the same page as well

542 (O,M) Fuel pump open, bad ground or always on – – Power / Fuel Pump Circuits

543 (O) Fuel pump monitor circuit shows no power – Power / Fuel Pump Circuits

PCM Monitors fuel pump power when key is on, that's what these 2 codes are for
But the fuel pump should only have 12v for 2 seconds with key on, then no volts until engine starts(above 400rpms)

Did you every apply 12volts to the pump with key on/engine off?
If so that would set 542, because it shouldn't have 12v


Easy test for fuel pump on OBD1 system
OBD1 connector in engine bay looks like this: https://www.therangerstation.com/tec...v_testing2.gif

Fuel pump slot is labelled in drawing
That slot is the GROUND for the fuel pump relay
So get a jumper wire
Turn key on
Ground that slot with jumper wire and you should hear the Fuel pump relay "click" closed and fuel pump should come on, its not quiet
If no "click" then key is not on or fuel pump relay coil has no 12volts from EEC(PCM) relay

If you hear the "click" but no fuel pump sound then fuel pump 12v wire OR ground wire at the tank is bad

If fuel pump is on try to start the engine
If engine still doesn't run or run well then there are 4 things
Clogged fuel filter
New pump is bad
Fuel Pressure Regulator(FPR) is stuck open, so bad
Water in the gas tank, also called "bad gas", all gasoline has some water in it, too much and its "bad gas", and water is heavier than gasoline so it sinks to the bottom of the tank.........where the fuel pump sits

 

Hopefully this is how to reply. Sorry forgot to put code description in.
12v when key kicks on for a second or two then drops to about 9v the KOEO. Do hear fuel pump kick on also.
Shop said they cleaned out tank but problem persisted.
Fuel filter was replaced also at shop.
Old pump and new pump both symptoms. Will check out the FPR. Thought I would reach out here as wife is not to keen on the old ranger with the bed half off in the back yard 😂

 

thanks for the info

 

So I changed out fuel pressure regulator and cleaned up the ground wire to no avail. I am getting fuel to cylinders. All spark are black and wet. I had disconnected the battery and now no codes are coming across. To me it is sounding back to a potential electrical issue.

 

I got the bugger running finally. Finally restarted running every thing and my distributor rotor was burned up. Still throwing a MAF code even though a new sensor was put on in the shop. Could the MAF manifold be an issue?

 

Which MAF code?

Up thru 1998 or so MAF sensors have 4 wires and 2 circuits
Has a 5volt sensor
And has a 12volt heater

Unplug the 4 wire connector for testing
Should be a Red(12v) wire and a Black(Ground) wire for the heater circuit, key on, test for 12v between them, if not bad wire

Then the sensor part has blue/red and tan/blue wires
You need to test these with engine running and MAF connected
ASSUMING heater power is OK

Unless you have Needle volt meter probes use sewing pins to pierce the two wires, push them in at an angle and far enough apart to not short together
Engine idling should show about 0.7v to 1.5volt depends on idle RPMs, if you raise the RPMs voltage should go up
If it shows -volts that's OK, wires(+ and -) are just reversed on the volt meter, but you should see same results/range

Unless the MAF sensor is not seated correctly in the housing then no the housing would not effect its reading

MAF sensor is there to WEIGH the incoming air, its a MASS air flow sensor
Computer already knows EXACTLY how much air is coming into a 3 LITER engine at any RPM, its just Math

Gasoline's air/fuel ratio is 14.7 to 1............and this is a WEIGHT RATIO, not volume
14.7 pounds of air to 1 pound of gasoline
14.7grams of air to 1 gram of gasoline
This is why fuel injectors are sold and rated in POUNDS PER HOUR(lb/h) of gasoline delivered

Gasoline's weight changes very little with temp or altitude above sea level
Air on the other hand changes A LOT with temp and altitude
That's how "hot air" balloons can fly, warmer air is lighter, "hot air rises"
Its why Cold Air Intakes are popular, the colder the air the heavier it is so more gasoline can be added and more power released

In places like Denver, 5,000ft elevation, warm or cold, the air is much lighter so less gasoline can be added and less power

MAF sensor has a heated wire(the 12volts), the sensor measures how fast the temperature changes on that wire as the incoming air cools it down, this denotes the WEIGHT of the air
It only measures about 10-15% of the incoming air, so small errors at the sensor are compounded times 10 in the computer
And if there is an air leak or vacuum leak then ALL the incoming air is not passing thru the MAF sensor, and that would be an error

 

Just ran codes again. 157 and 159. Also threw a 998

 

Unlike you I don't have them memorized, lol
157 Mass Air Flow signal is/was low or grounded – MAF
158 MAF sensor is/was high or short to power – MAF
159 MAF sensor is/was out of range – MAF

So it didn't do 158

Means voltage was low and out of range low
So can you test the heater voltage and sensor voltage?

998 Did not pass Key On Engine Off test yet (Get 111 in KOEO first)
This code doesn't matter

 

11.7 volts on red and black and 5.27 volts on idle on

 

11.7 is fine for heater

5.27 is an odd one, not sure what to make of that????

 

Well. I let it run for a bit since it is little cold here. Went back out and my check engine light was off and my voltage was in range.