fuel pump replaced pressure still drops - JeepForum.com
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post #1 of 2 Old 05-03-2009, 07:53 PM Thread Starter
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Join Date: Jan 2009
Location: Carson City NV
Posts: 19
fuel pump replaced pressure still drops

I just spent 3 days changing my 1992 Jeep cherokee 4.0L 4WD
in tank fuel pump-
Reason I replaced it was for an abrupt drop to zero of fuel pressure
at the injection rail when the fuel pump stopped- was told pump check valve?
I figured this would stop the longer than average crank time
on start up?
The first pump I put in acted the same way- pressure dropped to zero
right after the pump stopped-
so I took it back and got another pump- assuming the check valve
in the new pump was defective- well--- the next new pump did the same thing-
Now-- I have changed the fuel filter- changed the fuel pressure regulator
on the fuel rail- I have check the injectors for leaks- no leaking injectors-
I pulled the fuel rail off the manifold- pressurized the rail- no leak-
I am told-- this Jeep should hold fuel pressure at the rail when the
pump stops- maybe a leak down of 1 lb per hour-
I have decided to live with the longer than normal crank time-
But- am wondering about maybe a check valve between the pump
and fuel filter- in line? anybody heard of such a thing?

fiddlin1 is offline  
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post #2 of 2 Old 05-03-2009, 08:48 PM
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2003 TJ Wrangler 
Join Date: Sep 2008
Location: Springfield
Posts: 315
Check your return fuel line ,back to tank, if this is clogged, or plugged it will not let fuel flow out for long or tends to syphon fuel back to tank when shut off ,I had this problem...... and it creates hard starts, this may not be the case with your problem ,but its just my guess,.it seems to be a common problem though.. Hope this helps
RoscoeJ is offline  

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