Fuel Pressure Regulator - Ruptured Diaphram

Fuel Pressure Regulator -Ruptured Diaphram

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I have a 2001 Jimmy 125,000 miles - Replaced original Fuel pump, Spider ,and fuel filter. After 3 months of running great , the Fuel Pressure Regulator failed . Installed new one and it lasted about three days. Now I'm going on the fourth one . They only last a few days then the diaphragm ruptures.
Has anyone had this trouble ? If so what was a solution ?


UP DATE : I just installed another new FPR I hooked up the lines and checked the pressure to see if the new one leaked. Everything looked OK . I relieved the pressure at the test gage . When I removed the fuel lines to begin putting the plenum on a little gas ran out of the large fuel line (this would be normal since the line in vertical and a little gas would be in it)
When I removed the small fuel line it had pressure on it and squirted gas out .
Is this normal ?
Any help would be appreciated !!
Best Regards !!
Dave

There is only one thing that will cause the fuel pressure regulator diaphragm to continually rupture, a restriction in the return fuel line. If the regulator is exposed to ~75psi or greater, the diaphragm will rupture. Check for kinks in the line from the fuel metering body back to the tank. If necessary, disconnect the line at the fuel pump module and at the metering block and check for restriction. There is a flexible section of line, just above the transmission, that can easily kink if care is not taken when installing the transmission.

old master
I took the Sorenson FPR back to the parts store (third one) and they gave me a store gift card for the cost of the FPR . Went to another supplier and bought a BW brand . Looking at the BW brand you get a perception that its better quality . The seal around the body looks better and some of the parts are brass, but the seal has not been the problem .

I disconnected the return line at the tank and fuel squirted out . The BW brand has now lasted since 11-28 . I have left the fuel cap a little loose . Would a kink in the EVAP line be enough to cause back pressure? I did find a kink in the line caused by the tow service used when the original fuel pump died .

Best Regards!!

When the engine is off, there should be zero pressure on the return line at the fuel pump module connection. You might experience some fuel running out, but not under any pressure, gravity only. If it has pressure, (fuel sprays out) at that connection, there is a restriction in the fuel pump module. A kink in the EVAP system could cause vacuum in the tank, but certainly not pressure. If you remove the return line at the fuel metering block, and at the tank, you should be able to blow through it very easily. Might want to double check the line where it was kinked.

FYI: The fuel pump maximum output pressure should be 73psi to 108psi, more than enough to rupture the diaphragm if restricted downstream of the regulator.

I should have been more specific. I had the fuel lines connected to the injector with the plenum and coil wire removed when I pulled the return line at the tank. That's why it squirted.

At this point I m driving short distances to see what happens .

Again thanks for input !!

I understand. It doesn't matter if the lines are connected at the injector assembly, what matters is if the pump was running when you disconnected the line. If the pump was running, there will be pressure on the return line at the fuel pump module. If the pump was not running, no pressure.

That's what I meant to say I had the lines hooked up at the injector so I could energize the pump and turn key off quickly. Coil wire was just disconnected for safety.

Where would be the easiest place to hook up a gage to test for pressure on the tank . At the gas cap. I have a shop full of tools so I could come up with a way to hook up a gage just about any where. Or would it tell me anything .

First thing is to connect a fuel pressure tester to the service port by the distributor. In the underhood fuse panel on your 2001, there is a vacant terminal next to the fuel pump relay. This is the "pump prime" connection, and it is used for checking the fuel delivery system. The circuit runs directly to the fuel pump. Install a fused jumper wire from battery positive to the pump prime terminal:
http://i561.photobucket.com/albums/ss58/cwhook/DSC_0154-Copy-1.jpg

After the fuel pressure stabilizes on the tester, write the reading down. Then remove the jumper wire, wait 10 minutes, write down the pressure reading again. Post both readings.

We'll address this later:
If there is a restriction in the return line, the tank will not be pressurized. Only the return line would be pressurized. Installing a pressure gage on the return line would expose the fuel pressure regulator to the maximum output pressure of the pump... ya can't do that.

OK I understand the test to conduct .
It will take me a couple of days, I have to go Hendersonville Tn tomorrow and I have to get a new pressure gage ,the one I have is leaking inside the glass.

Are there any OBD codes that would tell us anything ? I have an Actron OBDII

The PCM does not monitor the fuel delivery system, so it can't set any DTC's in memory, or turn the SES light on.

EDIT: Just to clarify.... If there are problems with the fuel delivery system, such as pressure being too high or too low, it may or may not show up as a lean or rich condition by the oxygen sensors. There are no sensors for checking fuel pressure or leakdown.

OK I just wanted to verify that.
I will post results as soon as possible


Just some past info . This is the fourth FPR (BW Brand )and the Jimmy is running OK for now .

The first two failures resulted in rough idle and of course . Codes P300 172/175 O2 sensors trying to adjust .

The third FPR failure was so bad that it hydro- locked number five cyl.
Full stream of gas coming out FPR vent line.

Yup, seen that before. Definitely a restriction in the return line....somewhere.

Ok I will focus in on return line.



By the way ,I see you are in Belleville, Michigan. I used to fly into Ypsi airport a lot . Take Ecorse to 94 then on to Detroit or Romulus (K-H ).

That would be Willow Run airport, (1.5 miles due North of me). It was the home of "Rosie the Riveter" where they built B29's and just over 9,000 B24 Liberators during WWII. Did you fly for Kalitta? The airport is used, almost entirely, for freight now, and Kalitta still calls it "home".

I don't know why I called it Ypsi Airport . I knew it as Willow Run . We flew in there nearly every trip to Detroit . I spent a lot of time in Ypsi. at the Motor Wheel Plant . Knew Bob the Plant manager , Wes Dickerson ( he flew the Pontiac Hot Air Balloon ) , Garth Lawrence and lots of others. I was the Pattern Tooling Eng. for Wheland Foundry for over 25 years . We supplied brake drums and rotors to MW They told me the B29 Plant was built on a 1/2 degree incline to roll the planes down the incline for production. Also I saw what I believe was the oldest Buick Dealer in the US and a house that was used for the underground railroad. Our pilots loved Willow Run As you know the runways come in all directions in case the new B29 's where in trouble . But they would get us out of trouble . If Detroit closed for snow we could leave Willow Run when we wanted to .

We met a lot of the Kalitta pilots and you always went away with a story . Some of those guys where a little rough but they got the job done
Saw the Dragsters over there all the time .

Also we still make the B29 drum at the old Wheland Plant in Chattanoga
Its a steel shell drum with a cast iron liner. The "Lorries " still use them . Moved the MW process from their Lansing Plant

Small world sometimes

Know what ya mean about runways in all directions ;) None of the flight paths are directly overhead here: I'm due South of the 5R approach. Very busy airport and Kalitta is the only passenger service that uses it. Ypsi is a cool old town, a group of us old duffers go there every Monday night for burgers at a bar in Depot Town. Ypsi does have some areas that I don't recommend visiting though;) GM built automatic transmissions in the main plant at Willow Run until it closed in 2010. They auctioned off the equipment to some company in China, (go figure) and they came and removed it, a few months ago. There's some talk going around town about leveling the building... sad. The Yankee Air Museum, (East side of runways) wants to buy the building, if it can secure the funds. It's one of the largest totally enclosed buildings, a massive place to say the least. Ford just got done completely leveling the Wixom, Michigan assembly plant a few months ago. They built Lincolns there for years! That was another massive plant. Google maps satellite view still shows it standing, NW corner of I-96 and Wixom road.

let me know what you find with the tests and return line.

Will do -
It may take me a few days since it has gotten really cold down here in Tn Highs are only 44* ( I know your laughing now ) and Ive got an OMC Cobra outdrive torn apart in my garage and the shop is full of Triumphs ,so for now I have to work outside .


I know I'm getting ahead of myself , but if the return line is clear will that point to an obstruction in the fuel pump ?


A new fuel pump was put in when all this started along with the new style spider.
Fuel pump/Airtec Spider / Summit Racing Lasted three months then the FPR failed and then two more after that within two days of each other.

Right now its running Ok with the BW FPR but I'm afraid to go very far .

Thanks Greatly !!

44??? That's shorts & a tee shirt around here! We won't see that again until next March... if we're lucky! All the Cobra's better be winterized by now around here.


Provided the return line is clear from the fuel metering block back to the fuel pump module, the restriction has to be in the module.

A new [Airtex] fuel pump was put in when all this started
Airtex pumps are.... uh.... how can I put this.... gently now.... not a good choice at all with this engine, destined for premature failure. I think I've seen every failure possible with them, but a restriction would be a first, nothing would surprise me with that pump.