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  #1  
Old May 30th, 2011, 20:09
DanDXJ DanDXJ is offline
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BMW fuel check valve

Info: 1990 XJ 4.0L Auto

My fuel pressure drops to zero within a minute of pump stopping. After searching for this I found a thread discussing an easy fix using an external check valve from a BMW. Does anyone know the year and model BMW this check valve is used for?

Thanks

Dandxj
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  #2  
Old May 30th, 2011, 21:15
Dragonslayer Dragonslayer is offline
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Re: BMW fuel check valve

BMW part # 16 14 9 068 988. Constant Pressure Valve.

It is for 1990 BMWs (several models). It was a fix for a factory recall involving fuel
pressure and long cranking starts.

Try www.bmaparts.com.
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  #3  
Old May 31st, 2011, 05:00
djgrayxj djgrayxj is offline
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Re: BMW fuel check valve

The first thing I would do is pull the vacuum hose off of the fuel pressure regulator and check for fuel their. If fuel is found you have a bad diaphragm in the regulator. Replace it. Then repeat pressure loss test.

NEXT Test:
Take a pair of Long Nose JawVice-grip http://www.northerntool.com/shop/tools/product_13061_13061?cm_mmc=Google-pe-_-Hand%20Tools-_-Pliers-_-15234&ci_sku=15234&ci_gpa=pe&ci_kw=vice%20grips&ct ype=2
[Second from left] put some rubber or plastic hose over the jaws [this will prevent damage to the fuel hose], look at the back of the fuel rail for the fuel hose leaving the fuel rail and pinch it off. This is the return line where I believe the check valve is located. Then repeat pressure loss test if pressure holds this should confirm faulty check valve.

If both of the above test pass test ok, then you probably have leaking fuel injectors.

Last edited by djgrayxj; May 31st, 2011 at 05:30.
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  #4  
Old May 31st, 2011, 05:03
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x99j x99j is offline
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Re: BMW fuel check valve

it will work for a 1990 xj. the years it does not work for are the returnless fuel systems 97ish - 2001
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Old May 31st, 2011, 14:51
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blubullett blubullett is offline
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Re: BMW fuel check valve

I saw a lot of claims of fuel lines blowing off because of heat soak expanding the fuel in the lanes. The general concensus was that it wasn't a good idea. Use your search and you might be able to find something more about it and decide if you want to do it.
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Old May 31st, 2011, 16:20
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birchlakeXJ birchlakeXJ is offline
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Re: BMW fuel check valve

Quote:
Originally Posted by x99j View Post
the years it does not work for are the returnless fuel systems 97ish - 2001
I have heard mixed results for earlier XJs. From somewhere in 96 or 97 (when the hell was it?) when they went to the returnless fuel delivery system to the 2001, it is a BAD idea.

Search for lots of light reading on this.
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Old May 31st, 2011, 16:23
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GSequoia GSequoia is offline
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Re: BMW fuel check valve

Why bother?

Just let the fuel pump spool up before starting. When you jump in turn the key from off to on, wait for the fuel pump to stop making noise, then continue on to start.

I've been doing that so long in my '89 that it's habit, I don't even think about it anymore.


PS - The XJ went to no return lines in 1996.
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Old May 31st, 2011, 20:17
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semperfi1371 semperfi1371 is offline
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Re: BMW fuel check valve

You can get the check valve on ebay for $10 or so, just do a search for fuel line check valve. That's where I got mine. That said, this did not resolve my issue which was long cranking times, which as it turns out is normal for my Renix system...though my pressure still drops immediately! (No, the valve is NOT in backwards and functions as intended) I believe the problem is in the return line, but I don't care as longa s she keeps starting!
Now if I could only figure out why my passenger side window will only go down & not up via either the master switch or door switch (unless I use 2 jumpers in the connector, 1 to ground or reverse the plug on the motor), I'll be in heaven!!!

Last edited by semperfi1371; May 31st, 2011 at 20:40.
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