1992 Ford Ranger Fuel Pressure Regulator Troubleshooting

Fuel pressure regulator problems always have symptoms associated with a failure of the pressure regulator. The 1992 Ford Ranger is no exception. An engine that lopes at an idle; has a heavy, raw fuel smell; emits black smoke from the exhaust; detonates under load; lacks power on acceleration; has reduced speed; bad hesitation; keeps fouling plugs; is hard to start; contaminates the oil with fuel or sets an oxygen sensor code very likely has such a problem. This is not to say that all these symptoms will occur simultaneously; it depends on the type of failure the regulator has experienced.

Instructions

1

Look for the aforementioned symptoms that would suggest a malfunction of the fuel pressure regulator.

2

Locate the regulator on the drivers side rear of the fuel rail. Inspect the regulator base for any evidence of fuel leakage from the O-ring. Any such sign requires a new O-ring if everything else checks out.

3

Pull the oil dipstick and test it for a fuel smell indicating excess fuel in the cylinders. Install the fuel pressure gauge onto the fuel rail Schrader valve. In appearance, this looks like a bicycle tire valve. Thread the gauge hose on this fitting. All pressure readings will now be displayed on the gauge.

4

Turn the key on without starting the truck and observe the fuel pressure gauge. The pressure must not be more than 40 psi or the regulator is bad. If the fuel pressure is low, the fuel pump or filter is bad.

5

Start the truck and observe the gauge. It must be 30 psi plus or minus about 1 pound. If it is higher, look at the vacuum hose for leaks and vacuum. Take the vacuum hose off and place a finger over the hose end to test for a vacuum. If the hose is in good shape, the regulator is the problem.

6

Check the return line for kinks restricting the return flow of fuel to the tank. Pull the vacuum hose off the regulator. Look in the regulator nipple and the hose for fuel indicating a torn diaphragm in the regulator. Look at the fuel pressure gauge with the hose off. It should have risen to 39 to 40 psi. If it hasnt risen, the regulator is bad. Install the vacuum hose and the pressure must drop to 30 psi.

7

Raise the engine rpm and watch the gauge. The pressure should very quickly rise to 40 psi and remain there as the engine is accelerated. It must return to 30 psi when returned to an idle. Any irregularity in performance requires replacement of the regulator.

8

Shut off the engine and watch the gauge. The fuel pressure must remain for a few minutes, dropping off very slowly. If the pressure drops right away, an injector is stuck open. When this happens, the remaining fuel pressure goes past the injector into its cylinder, washing down the cylinder. This will saturate the oil with gas and foul the plug.