Solved Fuel pressure problem.

[CDW6212R]

Getting closer.

Here is what I found…

For salvage fuel pressure regulator: mostly unavailable, and hard to find. There is a salvage yard near Tampa, about sixty miles from here, that has a salvage fuel pressure regulator for $150. None of the more local yards had this part available. This would finish the project, but would still be a 25 year old regulator.

For new regulator: Ford part is obsolete. There is no availability of any equivalent fuel pressure regulator with braided line attached to the regulator. The new part must have: a similar sized slip in fuel rail connection and o-rings, a vacuum control hose barb pointed straight away from the top of the regulator, fuel rail bolt holes spaced 1 5/8” on center apart, a bracket on the outside of the diaphragm (not welded around the middle of the diaphragm), and a fuel line connection opposite of the vacuum control hose barb. Of course, it must have similar pressure specifications.

Bosch units are not available. GP Sorensen has a fuel pressure regulator sold through Auto Zone , but the unit listed in the Auto Zone computer is not correct. The necessary part is GP Sorensen 800-521. (I hope). Thank you, @J_C. Hopefully, the research has already considered fuel pressure specifications.

If you want to use a new part, which will not have steel braid line, you will still need to make a connection between the truck fuel line and the new part. The steel braid line is incredibly strong, but has no ability to stretch or flex over a hose barb.

There is a suggestion on the Internet to cut the steel braid away from the braided fuel line, and the slide the exposed rubber fuel line over the hose barb for the new part. This seems VERY dangerous, as the rubber section of the braided fuel line, by itself, looks thin and fragile. (Pictures to follow). To make matters worse, this appears to be the high pressure side of the fuel system, rather that lower pressure return line. Be careful not to turn your truck into a bomb, or a monstrous fireball.

To safely hook to existing high pressure fuel line, you could remove about six feet of braided steel line and go all of the way back to hard line under the front of the driver‘s side fender. Then double flare the hard line and replace the entire section of steel braided line with fuel injection (high pressure) line. It would not seem safe to attach any rubber fuel line to hard line without flaring the hard line, especially on the high pressure side. I have never used a flare tool, do not know if they are available as loaner tools, and would prefer to keep the OEM steel braided line, if possible.

Another option is to disconnect the braided line at about the three or four foot length, using the existing in-line quick disconnect hardware. You could then recreate the section of fuel line between the new fuel pressure regulator and the quick disconnect. However, I could not locate any AN fittings for the braided line in Ace Hardware or Home Depot. There do not seem to be any DIY connections to steel braided fuel line. Further, none of the local hydraulic shops could make this connection.

Fortunately, there is a high end hydraulic fabrication shop about 20 miles from here that believes that they can make this new section of line using the existing fuel disconnect fitting and the new fuel pressure regulator. So I will try that route.

Still hoping that: 1). The Auto Zone GP Sorenson part arrives and fits properly, 2j. The custom hydraulic shop can in fact make the line, and 3). The Fuel Pressure Regulator is the source of the problem!!!

That's great research, well done.

I would prefer an OEM regulator only if it is readily available. A used one should be cheap, $20 or so max, it's a very simple part.

The idea of altering the fuel rail to accept an aftermarket FPR is the best answer given the cost and rarity of the OEM FPR. If that is going to work, choose a very common and popular Mustang 302 FPR. The aftermarket has made dozens of those, that would be the easiest to replace now or in the future. Those Fox Mustang 302's use the identical fuel system design, 35psi except for WOT(vacuum line disconnected), about 42psi.

 

[imp]

Same here

Keep in mind here the two different needs: fuel pressure REGULATION is the maintaining of pressure usable by the PCM programming for the injectors to run the engine, while PRESSURE RELIEF is keeping the maximum pressure developed at a safe level not capable of causing damage of any kind.

 

[CDW6212R]

All sequential EFI Fords prior to 1999 run at the same fuel pressures, so the FPR is designed to do the exact same thing in all of those. The shape, size, and connections to the fuel lines etc, will differ among many models, but functionally they are the same. It looks like the Explorer V6 FPR's are unique in size and shape etc, and the aftermarket hasn't ever made them. They are also so reliable, that there hasn't been a need for them.

 

[mostly_broncos]

Stupid question but did you try pulling the rail off with injectors attached and turn the key to see if injectors are leaking ? I did this once on a truck i pushed them into a spare manifold that i had laying around so they wouldnt fly off the rail but you might have to rig something up .

 

[TedJ]

had someone turn the key, while I monitored shraeder valve. Had gush of fuel for about two seconds, then system IMMEDIATELY returned to zero fuel pressure.

Is the pump being powered and do you have fuel pressure WHILE cranking? It sounds like the pump is just turning off.

The computer needs to know the engine is cranking to turn the fuel pump on. If you have a bad crank signal or similar input problem, the computer will do the 2 second prime but not run the pump. Check the RPM with a scan tool and verify that it shows the cranking RPM. The tach should also rise a bit to cranking RPM.

 

[4pointslow]

The fuel pressure regulator on a Ford return fuel system is called a hydro mechanical regulator.
The spring working against the diaphragm regulates fuel pressure to about 39.15 PSI key on engine off.
When the engine is started there is intake manifold vacuum applied to the vacuum line going to the fuel pressure regulator.
The vacuum lowers the fuel pressure to compensate for the vacuum in the intake sucking on the injector tips.
Engine vacuum is measured in inches of mercury or inHG, and fuel pressure is measured in PSI.
If you google PSI to inHG conversion you will find it is about .49 to 1.
So, with 20 inHG of vacuum you will have 10 psi of fuel pressure drop with vacuum applied, so with engine running at idle and 20 inHG of vacuum you would expect to see around 30 psi of fuel pressure.

If the fuel pressure leaks down, the test to see if it is a fuel pressure regulator is...
Have fuel pressure gauge attached to fuel rail.
Turn on key for two second prime of pump and watch pressure build.
As soon as the pump shuts off you would pinch off the return line and see if it holds pressure.
If it does you have a stuck open fuel pressure regulator.
If it doesn't hold pressure, you next pinch off the fuel supply hose just after the pump shuts off and if it now holds you have a problem with the one-way check valve in the pump or the hose from the pump to the sending unit is split or leaking.
Of course, it is not always possible to pinch off fuel lines like in the example of only having solid steel or plastic lines with no rubber to pinch off.

If the fuel pressure still leaks down with the fuel supply and return lines blocked off, you have leaking injectors.
I found a friend's car with leaking injectors, 5 were leaking and one was new. It caused rich and lean codes to be set in the PCM. Rich at start up and lean after it got going down the road for a bit.

 

[Mr. Alligator]

Stupid question but did you try pulling the rail off with injectors attached and turn the key to see if injectors are leaking ? I did this once on a truck i pushed them into a spare manifold that i had laying around so they wouldnt fly off the rail but you might have to rig something up .

^^^ I did not do that, and hope that the fuel pressure regulator is the issue.

I think that the regulator is the issue because I get immediate and total loss of fuel pressure as soon as the pump shuts off from the initial prime.

The fuel pump is works, it is a new Walbro, and I can hear it, and see it work with the ignition.

The fuel filter is almost new, and the tank is clean. The fuel filter is oriented in the correct direction, and shoots fuel out of the exit side, if I disconnect it.

The fuel is dumping out if the return line, which I can unhook at the tank (through the access panel) and watch shoot fuel almost immediately when the pump comes on.

The truck has run well, until this no-start issue. It is not hydro locked. My crankcase oil level has never increased with fuel.

I hope it is not my fuel injectors, although they are original. This is my basis for addressing the fuel pressure regulator.

Would you agree with the diagnosis and logic?

 

[donalds]

I hope it is not my fuel injectors, although they are origina

I have 2 sets of 6 off my 99 You need them you know where to find them

 

[mostly_broncos]

^^^ I did not do that, and hope that the fuel pressure regulator is the issue.

I think that the regulator is the issue because I get immediate and total loss of fuel pressure as soon as the pump shuts off from the initial prime.

The fuel pump is works, it is a new Walbro, and I can hear it, and see it work with the ignition.

The fuel filter is almost new, and the tank is clean. The fuel filter is oriented in the correct direction, and shoots fuel out of the exit side, if I disconnect it.

The fuel is dumping out if the return line, which I can unhook at the tank (through the access panel) and watch shoot fuel almost immediately when the pump comes on.

The truck has run well, until this no-start issue. It is not hydro locked. My crankcase oil level has never increased with fuel.

I hope it is not my fuel injectors, although they are original. This is my basis for addressing the fuel pressure regulator.

Would you agree with the diagnosis and logic?

Pull the return at the tank and cork it and see if there is pressure heck see if it runs like that.

Cut a line off an old pump and weld it shut maybe .

Its a thing people with f series trucks do if they have dual tanks and take one out.

 

[nevadabob9mm]

Might this be a vapor lock problem?

 

[Mr. Alligator]

Is the pump being powered and do you have fuel pressure WHILE cranking? It sounds like the pump is just turning off.

The computer needs to know the engine is cranking to turn the fuel pump on. If you have a bad crank signal or similar input problem, the computer will do the 2 second prime but not run the pump. Check the RPM with a scan tool and verify that it shows the cranking RPM. The tach should also rise a bit to cranking RPM.

The pump does shut off after initial surge/prime. But EVERY bit of the prime pressure is lost immediately, and fuel pushes back through and out the return line. This is before cranking.

I had fuel pressure loss before with a bad fuel pump check valve. The pump turned on, and shot fuel up to the shraeder valve. But all pressure was lost immediately and totally. And nothing came back through the return hose. It was a real odd thing to me… where in the devil did the fuel go??? Answer: back into the fuel tank, because of malfunction in the brand new fuel pump/ check valve.

 

[Mr. Alligator]

Pull the return at the tank and cork it and see if there is pressure heck see if it runs like that.

Cut a line off an old pump and weld it shut maybe .

Its a thing people with f series trucks do if they have dual tanks and take one out.

I did consider this, but was concerned about damaging a fuel line by crimping it with pliers. Also concerned about deadheading my fuel system and maybe damaging other fuel components. (Especially with new Walbro pump.)

If I were stranded, I would see if it ran with the fuel return line “corked”.

 

[Mr. Alligator]

All sequential EFI Fords prior to 1999 run at the same fuel pressures, so the FPR is designed to do the exact same thing in all of those. The shape, size, and connections to the fuel lines etc, will differ among many models, but functionally they are the same. It looks like the Explorer V6 FPR's are unique in size and shape etc, and the aftermarket hasn't ever made them. They are also so reliable, that there hasn't been a need for them.

The most unique aspect of the 97/98 Explorer fuel pressure regulator is that there is stainless steel braided line permanently attached to the supply side.

I think I have located a similar fuel pressure regulator, but it lacks the stainless steel braided line, and DIY connections for the stainless steel braided line seem to be nonexistent.

 

[Mr. Alligator]

I have 2 sets of 6 off my 99 You need them you know where to find them

That is awesomely kind. If I get this fixed and hooked up and still have no start…. I will contact you right away. Sometime people, you, are so kind, that it restores my faith in human nature, Thanks.

I have obtained the GP Sorenson FPR, and will go to get the custom made fuel line from the top end hydraulic shop in the a.m. Maybe get hooked back up very soon.

Thanks again, sir.

 

[Mr. Alligator]

Might this be a vapor lock problem?

I think vapor lock is very rare with fuel injection. And the most recent no-start happened with a cold engine. Good thought, though.

Thanks.

 

[CDW6212R]

The thought of the fuel pump or pressure stopping after the initial priming is the last thing I'd address before doing other work or expense.

I would first force the fuel pump to run by triggering the relay manually. See if the pressure stays up, and if the engine starts with the pump forced to run. If it does, then the FPR is likely fine, and something is stopping the relay from powering the pump. If it still doesn't run, then the pressure is going somewhere besides the injectors(likely past the FPR and back to the tank).

It shouldn't be too hard to hot wire the pump relay in the Power Distribution Box(PDB). I think it may be fairly easy to put a jumper wire between any power source and the pump relay trigger terminal. I'd gently place a small gauge wire in the relay connector(with pump relay removed), just the strand of wire in there and carefully push the relay back in. Then the other end, bare wire in hand, when you want the pump to run, touch it to the battery until you want if to shut off. The relay barely needs current to trigger it when it's in place, so you could have anyone handle that jumper wire, or make it very long to reach inside if you need to do it alone(with switch or two bare ends etc).

 

[cujo2006]

I didn’t read through all the replies however if you didn’t figure this out yet the posts in here that say about pinching off the return line is about as accurate as you can get. Those pumps will dead head about 65-70 psi. That is not high enough to damage anything short term but it should definitely start and run. That would be a tell tale sign that the reg is bad. Had this happen on a 5.0 and pinching it off was enough to get me home. But that reg wasn’t that hard to get.

 

[donalds]

I plan to be going to the junkyard on Sunday to get a rubber boot for a Honda accord intake I'm gonna see if I can find the assembly with the lines attached so you can put it back to stock it's only like like $13And then I'll send it to you these parts are getting rare if I can find one still

I have the ford o ring to brand new a few of them actually ya know that blue or green one that goes in the rail itself

And I was just recently there and saw a perfect regulator and thought to myself I have a returnless system I don't need that

What exactly will I need tools wise to take it apart besides basic tools

You might end up with a box of goodness soon lol

And I can bench test it at the junkyard with my mighty vac

 

[J_C]

^ Same question, what tool is needed to disconnect the PR hose connector from its male mating connector.

I have this picture, it's supposedly the male end that the female end on the PR hose plugs into. Looks like a couple o-rings on it, which was giving me thoughts like if you want to see if fuel pump still runs after initial 2 seconds, you could just disconnect the hose to it, and stick it in a gas can to see if fuel is still flowing while cranking to start the engine. I mean the thought was, if you disconnect this 25 year old connector, it may need a couple new o-rings to seal again.

I got the pic from the following topic on JustAnswer where someone came up with a few coupler adapters to make regular fuel line work with the other pressure regulators.

https://www.justanswer.com/car/87hbo-explorer-need-replace-original-fuel-pressure.html

For some reason I couldn't get that Justanswer page link above to load on latest version of chrome, stopped 10% of the way but an old version of Firefox worked.

On a side note, my mother may have COVID, have to care for her, so if I disappear for a long time, I'm probably dead. My immune system has been poor for a while now so who knows....

 

[Lee's Automotive]

^ Same question, what tool is needed to disconnect the PR hose connector from its male mating connector.

I have this picture, it's supposedly the male end that the female end on the PR hose plugs into. Looks like a couple o-rings on it, which was giving me thoughts like if you want to see if fuel pump still runs after initial 2 seconds, you could just disconnect the hose to it, and stick it in a gas can to see if fuel is still flowing while cranking to start the engine. I mean the thought was, if you disconnect this 25 year old connector, it may need a couple new o-rings to seal again.

I got the pic from the following topic on JustAnswer where someone came up with a few coupler adapters to make regular fuel line work with the other pressure regulators.

https://www.justanswer.com/car/87hbo-explorer-need-replace-original-fuel-pressure.html

For some reason I couldn't get that Justanswer page link above to load on latest version of chrome, stopped 10% of the way but an old version of Firefox worked.

View attachment 432925

On a side note, my mother may have COVID, have to care for her, so if I disappear for a long time, I'm probably dead. My immune system has been poor for a while now so who knows....

Sorry to hear about your mom praying for yall be safe bro