How to: Ford Explorer Ranger Fuel pressure test procedure

[lytleman]

Whether the system fuel pressure gets up to 65-72 psi or that the pressure stays there when the key is off?

Are you having driveability/starting issues?

On the returnless fuel system, the fuel pump is the driving force behind system pressure...Remember, in this system design, there is no vacuum line to vary the fuel pressure based on engine load via vacuum...Since there is also no fuel return line, the injectors, fuel filter, and the fuel damper[which is used to smooth out fuel pulsations from the pump] will determine the delivery of fuel to the engine... The regulator is apparently in the system to "vent" excess pressure back to the tank while maintaining system pressure in case the system pressure goes higher than designed...

The pump and the injectors will also act to maintain fuel system pressure when the engine is off...My understanding is that Ford went to the returnless system and subsequent higher fuel pressure to fight iisues with heat soak causing vaporizing in the lower pressured fuel lines and difficult hot starting...

The pump has a typical check valve in the output port to stop backflow of fuel back into the tank and the injectors obviously have solenoids to turn on and turn off the fuel flow and keep the fuel supply at the ready on demand from the PCM...

Typical leakdown issues would be either a defective injector bleeding through the solenoid and/or a defective pump check valve in the pump itself...In the years that I have worked with the Ford returnless systems in converted Rangers and other vehicles using the Ford system I have only had to replace a fuel pressure regulator and that was when rust from the fuel tank caused the bladder to stick open and bypass the majority of the fuel volume back to the tank instead of supplying the fuel rail...

Saying the pump had the check valve in the output port helped alot, I wasn't sure if it was another part in the fuel tank assembly. Thanks

 

[JHT]

Dumb question - What is the difference between a tire pressure gauge and a fuel pressure gauge? A Schrader valve is the same as a tire valve and several pictures show a single hose going to the gauge.

 

[Farmtruckracer]

Just wanted to pass on some info of a fuel pressure problem I had to maybe help someone in future.
My 2003 Explorer with 4.6l developed an issue that would take longer cranks to start, or have to crank a couple times, but would always eventually start. I tested fuel pressure and it made the pressure it was supposed to but dropped to zero as soon as the engine was shut off. After searching here and many other resources I figured it was the check valve at the pump, and it seemed that I had to buy the whole pump, sending unit assembly for around $330. (a Motorcraft one can be found for around $230 if you look hard enough)
Before coughing up the money I decided to drop the tank and examine the pump assembly. I found that the plastic flex tube from the pump output to the top plate of the assembly had a pin hole causing the fuel to drain back to tank when the pump wasn't on. I think the hole was caused from the tube rubbing on one of the shafts the pump housing sort of slides on.
I was able to locate some 5/16" submersible (submersible is key here) fuel line rated for 100psi, locally for the great price of $30 per ft (can be found for less online) along with high pressure rated hose clamps to take the place of the tube. (I believe the plastic tube is actually heated then clamped on from the factory. I used a razor knife to cut it off) Less than half the hose was used and you need to make sure to have some slack in it because part of the pump bracket move up & down. If I were to do it again, I would probably just use the whole hose with it routed with a loop.
I'm happy to say it worked great, and is a much cheaper solution than the whole assembly.
This project took about 6 hrs, but I wasn't making the best time since I was up for over 30 hrs, had to drain a full tank of gas, (not good planning on that part) and had to spend time making calls to locate and get the special hose. I also suggest a helper to wrestle with the tank, it takes a little bit of persuasion at the front where it tucks over the cross-member.

 

[darrell milgrim]

Same problem with my 2001 ford sport trac. I think the fuel in rail is turning to vapor. I would like to know how insulated fuel rail works.

 

[irbydon32]

hey guys i need some help and i have a 99 sport 4x4 shoc and i inhearted it from my uncle ( rest his soul) and i have spark but i barley have any fuel shoot out of the test port and before he passed i put a new ff on it and when i did that it ran better for awhile then he was driving home and it just quit on him and idk enuff about fords to know what im dealing with so any help would be greatly Appreciated

 

[2000StreetRod]

From your description your Sport may have a weak fuel pump but I suggest that you measure the fuel pressure before expending the cost and time to replace the pump.