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Fuel Rail Failure after check valve

XJTripp

NAXJA Forum User
I have a 2001 Cherokee 4.0. The fuel pump check valve became ineffective and the thing took 2-3 tries to start every time. I basically wore a starter out before I took action. I put in an in-line check valve just like I had done previously with my 89 and it worked like a charm. Starts at the touch of the key --- for one day---. Today I was driving and smoke started pouring from the engine bay. Seems the fuel damper on the fuel rail sprang a leak and discharged like a shower head onto the intake. Luckily no fire.

I don't see how, but it must be related. Anyone else installed a check valve in their fuel line?

Possible theory - the pressure regulator is on the fuel pump, have I isolated it from the regulator and thus caused an overpressure condition on the fuel rail? Seems like when the pump is pumping the check valve would be open, right? So this shouldn't happen- right?

Other theory, the damper is just bad and I need to replace it and try again.

Anybody have a 2001 or 2000 that they added a check valve to?
 
Yup. Took it off after the plastic fuel line section kept separating from the metal section of the line and the fuel dampener on the fuel rail kept popping open.

I figure that the fuel in the fuel rail expands from heat soak and has enough pressure to overwhelm the dampener and pop it loose.
 
Is this on 2000 and 2001 only? Been thinking about adding an inline check valve to my 99 to help with the starting, but wondering now if I'd have this same problem. Is this a 97+ issue?
 
Thanks Tim,

I'm taking the check valve out.

UNCC, I think the way you can tell is that if you have a fuel return line and a pressure regulator on the engine - I think its near the front of the engine with an inlet, outlet and a vacuum connection- then you are safe with the check valve.

On the other hand if you do not have a return line, then don't do this.
 
Thanks Tim,

I'm taking the check valve out.

UNCC, I think the way you can tell is that if you have a fuel return line and a pressure regulator on the engine - I think its near the front of the engine with an inlet, outlet and a vacuum connection- then you are safe with the check valve.

On the other hand if you do not have a return line, then don't do this.

Ok. Actually just messed with the check valve on a 89 last week and noticed that it's not in the same spot in mine. I think i'll hold off on doing this to mine until more research can be done.
 
I read on another forum about this type of failure after adding a check valve. I have no idea on the year or location, just that he had the same type of failure.
 
I doubt the type is important, but it was the bmw valve that I succesfully used on my 1989. I think that when pressure rises at the rail, then the check valve shuts. My pressure regulator is on the fuel pump on this 2001 model and now the damper that is on the fuel rail handles the situation. It just got too much pressure.

As a side note. I dissasembled the damper and the o -ring looks good. I took out the check valve and reassembled everything and the damper still leaks at the seal. No one seems to carry the seal. I'm going hunting for a used rail from a friend down the road who has a business of rebuilding XJ's.

I hate this thing.

Thanks for the input. Anybody know where to buy a new damper or damper seal for a 2001?
 
Anybody know where to buy a new damper or damper seal for a 2001?

Been there, tried that. Even though there is a part number on the dampener itself, there are no service parts available for the 97-01 fuel rail. You purchase a whole new fuel rail or nothing.
 
I have a 2001 Cherokee 4.0. The fuel pump check valve became ineffective and the thing took 2-3 tries to start every time. I basically wore a starter out before I took action. I put in an in-line check valve just like I had done previously with my 89 and it worked like a charm. Starts at the touch of the key --- for one day---. Today I was driving and smoke started pouring from the engine bay. Seems the fuel damper on the fuel rail sprang a leak and discharged like a shower head onto the intake. Luckily no fire.

I don't see how, but it must be related. Anyone else installed a check valve in their fuel line?

Possible theory - the pressure regulator is on the fuel pump, have I isolated it from the regulator and thus caused an overpressure condition on the fuel rail? Seems like when the pump is pumping the check valve would be open, right? So this shouldn't happen- right?

Other theory, the damper is just bad and I need to replace it and try again.

Anybody have a 2001 or 2000 that they added a check valve to?
i did the bmw check valve on my 99 when my xj had the same symtoms. well 2 days later i blew:explosion the fuel diaphram, just like you. when i stuck a fuel pressure guage on the rail, the fuel pressure climbed to 110 with the xj turned off. this mod does not work on 97+ xj's do to the redesigned fuel system! i had to get a new fuel rail from junk yard (25$) and a new fuel pump assembly. now i start on the first try! mike
 
Why don't you guys just turn the key to on, wait a few seconds, then start it? If I get in my Jeep and start cranking it will take days to start. If I wait 3 seconds it starts immediatly.
 
Doesnt work. I had my 99 check valve installed all the way by the tank and it still blue off up front. And The turn the key and wait doesnt work either. You have to turn key wait . Turn key and wait . if your lucky it will start if not u gotta do it again. You have to prime the whole line then the injectors. When you let the car sit over nite all the gas goes back into the tank basically. On my 99 just replacing pump.


Or put your check valve back by the pump to give the fuel more volume to expand before blowing a line off.
 
I put the check valve (a BMW part) in my '99 just off the fuel tank. Didn't fix the slow starting issue and I'm back to square one. It's worse in the summer.
 
Why don't you guys just turn the key to on, wait a few seconds, then start it? If I get in my Jeep and start cranking it will take days to start. If I wait 3 seconds it starts immediatly.
thats where i installed mine and guess what almost happened? :flame:
 
your valve must not be the problem then. Because bmw valve if installed correct way will fix your start problem if your pump valve is dead. But at the same time it will create worse problems if you have a 97 and up. by blowing lines off, and springing leaks in ur injectors lol


I put the check valve (a BMW part) in my '99 just off the fuel tank. Didn't fix the slow starting issue and I'm back to square one. It's worse in the summer.
 
On this guy's 98, the first prime would take it to 20psi, then it would drop 5psi in the 2 seconds it took to reprime it to 35psi, then drop to 30 psi, then the third time would take it up to 44psi. You could watch it go from 44psi to <10psi in 10 seconds when turning off the vehicle.
 
Would turning the key on and off a few times before attempting to start the engine help? I always do that when I work on the injector rail or if I know the rail pressure is low.

How about installing a momemtory switch to run the fuel pump. Simply turn the ignition on, press and hold the primer switch a few seconds then crank/start the engine.
 
I say fix the culprit instead of putting a bandaid on it, since you know. Dropping a tank isn't that bad if it's empty.
 
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