I have a ‘92 Ford Ranger 4.0 6 cylinder. During short trips around town it does ok but is running rough. I tried to drive it a little farther and it had time to warm up. It suddenly dumped fuel into the cylinders and intake. We took it to a mechanic and he said it was a bad injector and changed them all out. We also changed the idle control sensor. I got it back a few days ago and now the same thing has happened. What else, beside the injectors, can cause everything to load up with gas?

 

Welcome to the forum

Mechanic should have tested FPR(fuel pressure regulator) already but you can as well
The FPR should be behind and below alternator on lower intake manifold
It has the Return fuel line connected to it, AND...............a vacuum hose, remove vacuum hose and check it for gasoline, if found replace FPR, its leaking
FPR diaphragm can leak and the vacuum hose will suck that fuel into intake causing Rich running


You can easily test if an injector is leaking by using "Clear Flooded Engine" routine which is built-in to ALL fuel injection computers
If you turn on the key
Press gas pedal down to the floor, and hold it down, the computer will turn off all fuel injectors, that the Clear Floor Engine routine

Now crank engine over holding gas pedal down all the way
Engine should NOT start, it should NOT fire at all, injectors are off

If engine fires then fuel is leaking in from somewhere

When you release gas pedal injectors will start, if engine fires and gets above 400RPM then computer turn on injectors regardless of gas pedal position


Why do you think engine is flooding?

 

Thank you. There was no gas in the vacuum hose. It even dumps gas into the intake and cylinders with the key on while the engine is NOT running. While trying to clear flooded engine It does sound like the engine is trying to fire but will not because it is acting like it is vapor locked. We checked 2 plugs and both were wet with gas.

 

Fuel injection can't vapor lock, it runs with 20-60psi pressure in the line so the fuel in the lines can't boil/vaporize like the old days with no fuel pressure between tank and mechanical pump on the engine.

Fuel injectors all get 12volts with key on, its the Red wire that runs from one fuel injector to the next, a daisy chained 12v wire

The Computer Grounds a fuel injector to open it
In a 1992 4.0l the computer uses Batch Fire fuel injection, this means that 3 injectors will open at the same time, 2 on passenger side and 1 on drivers side, then on the next RPM the other 3 will open, 1 on passenger side and 2 on drivers side
So on each rotation of the crank 3 injectors open, this keeps the lower intake full of air:fuel mix, like a carb did, and when intake valve opens it sucks in the mix

But it also means if ONE WIRE back to computer is shorted to ground then 3 injectors will open with key on

So what you need to do is test if an injector is grounded with key on
I think passenger side is easiest to get at

Pull off an injector's 2 wire connector, the red wire will be 12v
Ford usually used a Tan wire for 3 injectors and White wire for other 3 injectors as the Ground wires
Test one injector with Tan wire and one with White wire
Use test light or volt meter hooked to battery +, and then test if tan or white wire is grounded, KEY ON

If so then that wire could be shorted to ground OR Computer is inside

If ground is found then you will need to unplug the computers larger connector and test again, if ground is gone then its a computer issue, if still grounded then wiring issue

Computer wiring seen here: Ford EEC-IV

Pins 58 and 59 are the fuel injector grounds

The picture at the top is what inside of computer should look like
See the 3 Blue capacitors.............these can leak and cause many different issue so if computer is ever out pull off the top and have a look, its out of warranty, lol

 

I am getting to work on the truck this weekend . Are there any other ways to test the fpr be sure that is not the problem before I test all the wires?

 

Take the FPR's fuel line off, put a towel down under it
Cycle key on and off, no fuel should come out of the FPR, it should hold fuel pressure up to 42psi with engine off

 

Is there a fuel relay switch and could that be the problem? Or, do you think it’s the computer? When you turn the key on there is 8 volts across ALL injectors and they do not shut off and they stay wide open with key on.

 

Injectors should all get 12volts key on, from the EEC Relay

Computer then Grounds each injector to open it, which it shouldn't do until engine is rotating, computer uses RPM signal/tach signal to start grounding injectors

If all injectors are grounded then its a computer issue, or all 6 injector ground wires are shorted to ground somewhere

Unplug any injector's connector, it has two wires Red one is the 12volts, the other wire is the Ground that runs to the computer
Key off, test if that wire is a ground
Key on, test if that wire is a ground

If key off is a ground then could be a shorted wire, could be, unplug computer and see if its still a ground, if so then it is shorted wires, if it no longer a ground then computer is the problem

If key off is not a ground but key on is............then its for sure a computer issue

 

Ok.. so the fuel pressure regulator is actually in the fuel pump correct? This would be the fuel damper on the fuel rail correct? My issue was my truck started stalling then would hydro lock. I pulled the plugs and they were wet and black. After pulling all the plugs I cranked over the engine and lots of gas in the cylinders/er was shooting out. After i cleared it all, I put all the plugs back in and wires. Tried starting it and it ended up locking again. So the cylinders are flooded with fuel again and I will have to repeat the clearing again by taking them back out and turning over the engine. I did replace the valve covers as well, and I guess I somehow hit that vaccuum line off to the fuel damper. Everytime I tried starting it, it was leaking fuel out of that vacuum side .. does this mean the diaphragm inside is bad? Hmmm.. either that or an injector stuck open? With 354,000 miles I might just replace them all. Hope this helps someone else as well.. stand back while cranking over the open cylinders too.. shoots out like a humpback whale! Lol

 

You should start your own thread, this thread is about a 1992 Ranger
If..................you have a 1997, or earlier, Ranger the fuel pressure regulator(FPR) is on the engine
If..................you have a 1998, or later Ranger, then the FPR is in the gas tank with fuel pump, and there would be a pulse damper on the engines fuel rail

You could put a hose and "catch can" on the damper and then crank engine to see if it hydro-locked again, if so then yes fuel injector is also leaking

All injectors leaking would be a computer issue, or major wiring issue

All fuel injection computers have a "Clear Flooded Engine" routine
Turn key on
Press gas pedal down to the floor and HOLD IT DOWN all the way<<<this turns OFF fuel injectors if engine is at 0 RPMs
Crank engine
It should not start, it should not even fire, no fuel, but it does have spark
If it fires then fuel is leaking in

With all spark plugs out do the above test, crank engine(dampers hose still unhooked) if ALL cylinders are spraying out fuel then its a computer issue, if just one is spraying out fuel then thats the one with bad injector