Solved Fuel pressure problem.

[Lee's Automotive]

^ Where do you see either of those ebay part #s as compatible? They are not the same as the part #s I posted previously. I could be wrong about the part #s I posted but all info I got from topics where people had already done the research.

This part number 97JF-9C968-AB goes to 978F-9C968-AB when i search it up

 

[J_C]

I think those are just two different parts that search engines are erroneously listing as nearest-match results, and Ford should have used more, different letters in them to differentiate them. They did the same thing with the OHV version F37Z9C968A by putting that "9C968" string in it.

 

[imp]

I'm thinking either a stuck open injector or bad fuel pressure regulator

There are hundreds of pressure regulators on the market, many having adjustable pressure output. I use one on my '94 GT Mustang. Pressure output must be compatible with make/model engine, of course.

 

[J_C]

^ At first I was thinking if you use one of those, you'd leave the existing regulator on the fuel rail, but how do you implement something like that with its regulated output, isn't that a bit different than ours ('97-98 SOHC with a return pipe) which are more like a pressure relief valve?

I mean it would have to be on the return line, no? Or are you suggesting to put it before the fuel rail, then get rid of the return line, plug it off at both ends (one end being fuel rail pressure regulator original mount point and other end is the tank sending unit pipe)?

Or am I getting it wrong and you just put it on the return line and the adjustment is made by measuring fuel pressure while you adjust it?

 

[Mr. Alligator]

^ At first I was thinking if you use one of those, you'd leave the existing regulator on the fuel rail, but how do you implement something like that with its regulated output, isn't that a bit different than ours ('97-98 SOHC with a return pipe) which are more like a pressure relief valve?

I mean it would have to be on the return line, no? Or are you suggesting to put it before the fuel rail, then get rid of the return line, plug it off at both ends (one end being fuel rail pressure regulator original mount point and other end is the tank sending unit pipe)?

Or am I getting it wrong and you just put it on the return line and the adjustment is made by measuring fuel pressure while you adjust it?

I was also wondering about that... and IF I was stuck on the road, which fortunately I am not, could I just insert a regulator in the return line to get home? OR could the return fuel line be blocked so that this truck could be driven?

Since I am immediately losing all fuel pressure, since I have a new high quality pump, since the engine is not hydro locking and has been recently running well, and since large amounts of fuel gush out of the return line as soon as the ignition is turned on …. I suspect the Fuel Pressure Regulator.

I am just waiting to remove the OEM regulator and chase parts.

 

[imp]

^ At first I was thinking if you use one of those, you'd leave the existing regulator on the fuel rail, but how do you implement something like that with its regulated output, isn't that a bit different than ours ('97-98 SOHC with a return pipe) which are more like a pressure relief valve?

I mean it would have to be on the return line, no? Or are you suggesting to put it before the fuel rail, then get rid of the return line, plug it off at both ends (one end being fuel rail pressure regulator original mount point and other end is the tank sending unit pipe)?

Or am I getting it wrong and you just put it on the return line and the adjustment is made by measuring fuel pressure while you adjust it?

A regulator may be thought of as a valve, operating in the fuel circuit, just like a variable resistor in an electrical circuit controls the flow of current, only we are controlling the flow of a liquid, fuel. the amount of engine vacuum present determines the position of a diaphragm, which mechanically opens and closes an exit allowing fuel to return to the line carrying it back to the tank. High vacuum, as at engine idle, opens the return to the tank to it's maximum, while a fast-running, highly-loaded engine with low vacuum causes the diaphragm to pinch off a large amount of the fuel flow (by lowering it's pressure) to the tank, making more available for the engine. It doesn't really matter where in the fuel circuit the regulator is operating, but logic places it in the fuel rail, from which the engine gets it's fuel, or after the rail, on it's way back to the tank. This is preferred, to get quick response from the engine.

In the case of the returnless fuel system, the system pressure is regulated from within the tank, by controlling the pump speed. This involves the PCM processing fuel pressure and temperature data taken from the fuel in the rail, at the engine, by a Fuel Temperature and Pressure Sensor, mounted on the rail. Both systems have advantages and disadvantages. Return-type brings underhood-warmed fuel back to the tank constantly, losing the cooler fuel advantage. Returnless generally extends pump life beyond that expected in return-type.

When I got my 2004 Ex, with returnless system, the FTP sensor failed, telling me so by DTC. It ran pretty much like normal, so I did some questioning. If FTPS quits working, PCM automatically runs fuel pump at maximum output, the excess from which dumps right back into the tank via a relief valve built into the pump assembly! Saves a roadside breakdown.

 

[Lee's Automotive]

A regulator may be thought of as a valve, operating in the fuel circuit, just like a variable resistor in an electrical circuit controls the flow of current, only we are controlling the flow of a liquid, fuel. the amount of engine vacuum present determines the position of a diaphragm, which mechanically opens and closes an exit allowing fuel to return to the line carrying it back to the tank. High vacuum, as at engine idle, opens the return to the tank to it's maximum, while a fast-running, highly-loaded engine with low vacuum causes the diaphragm to pinch off a large amount of the fuel flow (by lowering it's pressure) to the tank, making more available for the engine. It doesn't really matter where in the fuel circuit the regulator is operating, but logic places it in the fuel rail, from which the engine gets it's fuel, or after the rail, on it's way back to the tank. This is preferred, to get quick response from the engine.

In the case of the returnless fuel system, the system pressure is regulated from within the tank, by controlling the pump speed. This involves the PCM processing fuel pressure and temperature data taken from the fuel in the rail, at the engine, by a Fuel Temperature and Pressure Sensor, mounted on the rail. Both systems have advantages and disadvantages. Return-type brings underhood-warmed fuel back to the tank constantly, losing the cooler fuel advantage. Returnless generally extends pump life beyond that expected in return-type.

When I got my 2004 Ex, with returnless system, the FTP sensor failed, telling me so by DTC. It ran pretty much like normal, so I did some questioning. If FTPS quits working, PCM automatically runs fuel pump at maximum output, the excess from which dumps right back into the tank via a relief valve built into the pump assembly! Saves a roadside breakdown.

@Fix4Dirt So our pumps are PCM controlled?

 

[J_C]

the amount of engine vacuum present determines the position of a diaphragm, which mechanically opens and closes an exit allowing fuel to return to the line carrying it back to the tank. High vacuum, as at engine idle, opens the return to the tank to it's maximum, while a fast-running, highly-loaded engine with low vacuum causes the diaphragm to pinch off a large amount of the fuel flow (by lowering it's pressure) to the tank, making more available for the engine. It doesn't really matter where in the fuel circuit the regulator is operating, but logic places it in the fuel rail, from which the engine gets it's fuel, or after the rail, on it's way back to the tank.

Thanks this clarifies it. I didn't think about the aftermarket being vac operated.

 

[Fix4Dirt]

@Fix4Dirt So our pumps are PCM controlled?

im not too sure but my guess is yes when i run a pcm self test i hesr the pump. am i sure on that? no not really if you want i can go check, lemme do that

edit: How to: - Ford Explorer Fuel Pump Electrical Procedure

 

[donalds]

@Fix4Dirt So our pumps are PCM controlled?

In our generation the pcm can only activate the fuel pump relay
On off that's it
The gen 3 explorers have a fuel pressure sensor on the fuel rail and
The computer has complete control of the pump
Aka pump duty cycle

Hope that makes sense

 

[Lee's Automotive]

In our generation the pcm can only activate the fuel pump relay
On off that's it
The gen 3 explorers have a fuel pressure sensor on the fuel rail and
The computer has complete control of the pump
Aka pump duty cycle

Hope that makes sense

Yep, that makes sense thanks bro

 

[Mr. Alligator]

In our generation the pcm can only activate the fuel pump relay
On off that's it
The gen 3 explorers have a fuel pressure sensor on the fuel rail and
The computer has complete control of the pump
Aka pump duty cycle

Hope that makes sense

So the fuel pump primes, then runs all the time the engine is running?

Thanks for your wisdom.

 

[J_C]

^ AFAIK, they all run all the time, ours just never slows down, constant ~14V once engine is running.

 

[donalds]

Then the fuel pump primes, then runs all the time the engine is running?

Thanks for your wisdom.

Yes correct.

I run my wideband o2 sensor off that circuit so the sensor is only on when the car is running

 

[C420sailor]

Got a pick n pull around? Go rip the whole rail off a truck. This is the first FPR failure I’ve heard of, I’m sure you could roll the dice and end up with a good one

 

[imp]

@Fix4Dirt So our pumps are PCM controlled?

Yep. For a few years, a Fuel Pump Module separate of the PCM handled returnless data, but somewhere along the way that was incorporated entirely into the PCM.

 

[donalds]

Yep. For a few years, a Fuel Pump Module separate of the PCM handled returnless data, but somewhere along the way that was incorporated entirely into the PCM.

My 99 has no module for fuel just the pcm and a relay
The fuel pressure regulator is in the tank

 

[Lee's Automotive]

My 99 has no module for fuel just the pcm and a relay
The fuel pressure regulator is in the tank

Same here

 

[Mr. Alligator]

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!!!

 

[donalds]

If all else fails you can switch to a more common returnless style system

Just a suggestion