2002 2.5l Fuel Pressure Issue w/ New Pump
 

Searching here, I haven't found an example of what I'm seeing with my '02 2.5l X-type.

The car has a hard start and the fuel rail does not maintain any pressure without the engine running. Once running, the car runs and drives like normal and the fuel trims are good. I replaced the fuel pump less than a year ago, it has maybe 5k on it.

With the car running the fuel pressure is 48 PSI with a mechanical gauge and 54 PSI according to my scanner. Once I shut the car off, the pressure drops drastically to zero. Putting the car ON will initially pressurize the rail but it maybe lasts 1 second before going back to zero.

Here's a video showing running, key off, key ON and re-starting.


I know this system is return-less with a pressure sensor being used to modulate the pump. It seems like there's no issue with the pressure sensor and I'm guessing the injectors aren't leaking since the fuel trims are good and there's no misfire.

Is there a check valve in the pump like other cars?

Any other ideas?

Perhaps? =

https://www.partsgeek.com/gbproducts...waAm7dEALw_wcB

Or? =

https://www.partsgeek.com/gbproducts...EaApRPEALw_wcB

I doubt the pressure senor is faulty since it's relatively close to the mechanical gauge and changes just the same.

Are there established symptoms for a faulty fuel control module? Other than no pressure? I didn't see anything that matches my symptoms.

Sleeping on it, I'm leaning more to a faulty pump check valve.. even though it's new.

There is no check valve that I'm aware of in fuel system/pump.

Heed post #5 =

https://www.jaguarforums.com/forum/x...m-pump-167543/

Heed the p1338 part of pin out =

https://www.justanswer.com/jaguar/36...-2500-rpm.html

How else would pressure be maintained after the key on priming of the system or after the car is shut off?

The posts you linked dont match my symptoms. I have good pressure when running and zero issues driving.

Pressure is not maintained when you shut the key off. Thus the reason the fuel pump (controlled by modules and electronics) "primes" the system by running for a few seconds (if you don't immediately turn key to start) & then shuts itself off. Also why when many off these cars begin to have a failing fuel pump, you can turn the key on, wait for pressurization and then get it to start. I nursed mine for months before it gave up the ghost.

These cars are equipped a bit different than many because the fuel system does not have a return to tank system of fuel.

Return system or not, all EFI cars prime the system to make up for pressure loss after sitting. Pressure isn't going to be completely maintained and it will slowly depressurize on it's own. This is why you bleed the system manually at the schrader valve before working on the fuel system.

You described priming on this car the way I understand it to work on everything else. But the pressure shouldn't go back to zero PSI immediately after the pump stops, otherwise the prime would serve no purpose. If there's no check valve, the pump must be the positive displacement, one direction flow type and maybe that is acting up.

My car primes the system at key on, as it should, but the pressure bleeds off immediately following the prime.

https://www.jaguarforums.com/forum/x...sensor-210055/

fuel rail pressure sensors monitor the pressure in the fuel rail and report the reading to the engine control module. If any drop in pressure is detected, the engine control module compensates so that the fuel pump can restore the proper pressure. A valve controls this pressure.

https://www.jaguarforums.com/forum/x...e-help-125184/

I guess you know better than anyone else. Good luck with your quest.

It was the pump.

After swapping in a new Delphi pump, the system pressurized and stayed pressurized at key on, had good pressure running and stayed pressurized after key off. All symptoms are gone.

Cliffs: My 2nd Delphi pump ended up having another defective check valve so I built a check valve, fuel pressure regulated bypass system instead of replacing the pump again.


A few weeks after that last post the car started intermittently hard starting again and when I put a fuel gauge back on, it had the same pressure symptoms. It no longer held a prime and pressure dropped immediately after shutdown.

I reluctantly shot gunned a new module then a new pressure sensor with no change. The only other thing besides another defective pump check valve would be leaky injectors but that almost always has stumbling on startup from the leaking fuel.

I don't feel like dropping everything to do a 3rd fuel pump within a year and I'm not trying to cut the car up to do it that way either.

On return systems people use external in-line check valves when their pump check valve fails. On a return-less system you can't do that since it'll trap fuel at the rail.. which can heat and over pressurize. There's a point where the injectors won't open if there's too much pressure built up.

I thought why not put a check valve (1) in with a pressure regulated bypass so that the rail pressure can bleed off? It's the same concept as a return system but the bypass would have a FPR and an additional check valve (2)(opposite direction) to bleed off any pressure trapped by the first check valve. The second check valve in the bypass loop would keep the wrong side of the FPR from being pressurized as well. Ideally you want the check valve close to the tank but I didn't feel ok with having a bunch of additional connections and a FPR exposed to rocks etc. under the car. There's a nylon supply line in the engine bay that goes to the rail and is removable with quick connects. I built the check valve/ FPR bypass scenario using a spare line as a guide. This will also allow me to go back to stock in 10 mins if need be. I stayed away from no-name Chinesium FPRs and check valves mainly because it's the wife's car. I could have saved $80 by using a stock FPR of some sort but I didn't like the idea of dead heading the FPR when the pump pressure is higher than the potentially lower stock FPR set point. The 2nd check valve on the outlet side of the FPR would be shut from supply pressure. After hours of reading reviews etc. I went with an AEM FPR and Airtex check valves.

And.. It works. It'll hold the prime, start quick, runs fine and holds pressure after key-off. At first I adjusted the FPR so that fuel pressure does not drop after key-off. With the engine off, I adjusted the set screw till I started to see the pressure drop. Then, I threaded the set screw back in so I knew I'm just above the running pressure. This means the FPR won't be open normally but if the fuel is pressurized in the rail (via heat) after shutdown, it'll be able to bleed off if over running pressure.

This is pretty simple in concept but it's cool to see it work since I couldn't find another example of anyone doing this before. There's a bunch of different ways to do this and it can be more or less expensive based on your preference. Everything below was roughly $200.

The parts list is:
1x AEM 25-302BK FPR
2x Airtex CV8000 Fuel pump check valves
2x 1/4" NPT Male T fitting
3x 5/16" barb to 1/4" NPT Female
1x 5/16" barb to 1/4" NPT Male
1x -6AN O-Ring Hex plug
1x 1/8" NPT Hex plug
2x -6AN O-Ring (ORB) to 5/16" barb
1x Russell 640836 -6AN Male to 5/16" SAE (for stock hard line)
1x -6AN Female to 1/4" NPT Male
3' 5/16" Fuel injection hose (high pressure, not for carburetor systems)
Yellow Teflon PTFE for gas pipe threads
Various clamps.

https://imagizer.imageshack.com/v2/6...921/t9aCrT.jpg

Well done and only time will tell if it is as good as it seems (or as it looks). Well conceived and well executed! I feel sure there will be others welcoming your initiative.

Thank you!

About a hundred miles in the car threw a high fuel rail pressure code so I backed the regulator down to about 35psi.

It's got about 2k miles on it now with no codes or other issues.

Back in late December the AEM FPR started to leak where the diaphragm is held in place between the 2 FPR body halves. There was no visible damage to the diaphragm when I took it apart. It may have been as simple as the allen bolts loosening. I've read that's a common failure on aftermarket FPRs in general.

I decided to replace the FPR with a pricier Aeromotive unit, p/n 13109. It now has about 1k miles on it. I'll update this with any failures or milestones as they come.

https://imagizer.imageshack.com/v2/1...922/w7GLrg.jpg

Just an update. 3k miles and 5 months without issue.

Snipped your post to focus on this point.

I love what you did here but I have to admit I don't understand. A working check valve on the stock return-less system would also trap fuel at the fuel rail. Isn't this exactly why there is a check valve in the system? The system you designed and built also traps fuel at the fuel rail but at the pressure you set with the pressure regulator?

What would cause the fuel rail to over pressurize without your fuel return? The "priming" stage where the fuel pump runs at key On regardless of existing pressure?

The reason I ask is I am in the same boat. New fuel pump installed, hard starting after sitting, checked fuel pressure and it is perfect with the engine running but drops off very quickly with the engine off. I installed an in-line check valve and that hard start problem went away but since installing the check valve I have gotten a CEL with code for high fuel pressure. I'm trying to understand if and why the check valve (mine is down by the fuel filter) causes the high fuel rail pressure.

Snipped your post to focus on this point.

I love what you did here but I have to admit I don't understand. A working check valve on the stock return-less system would also trap fuel at the fuel rail. Isn't this exactly why there is a check valve in the system? The system you designed and built also traps fuel at the fuel rail but at the pressure you set with the pressure regulator?

What would cause the fuel rail to over pressurize without your fuel return? The "priming" stage where the fuel pump runs at key On regardless of existing pressure?

The reason I ask is I am in the same boat. New fuel pump installed, hard starting after sitting, checked fuel pressure and it is perfect with the engine running but drops off very quickly with the engine off. I installed an in-line check valve and that hard start problem went away but since installing the check valve I have gotten a CEL with code for high fuel pressure. I'm trying to understand if and why the check valve (mine is down by the fuel filter) causes the high fuel rail pressure.

Yes but the stock pump check valve also has some leak-by that seems to be more than some aftermarket check valves.

Exactly.

After the engine is turned off, heat will make the fuel expand and pressurize.

It depends on how well the check valve is working. If it leaks by slightly, you'll be emulating something like stock, like you're saying. On my setup, I actually did throw a high pressure code at first because the FPR was set too high. With no FPR, I would have definitely set the same code. Once I lowered the pressure, the code went away.

I mentioned my setup to a fellow engineerd at work and he said he's heard of doing similar in another car community (jeep maybe?) with a single check valve that leaks by at 30/40ish PSI. So there may be another single check valve solution but I never looked into it since I had already executed my solution.

Thanks much for your detailed replies, and very nice work with your set-up. I might make a copy.

Thanks. For what it's worth, this setup now has 13k miles on it.