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Old 07-30-2015, 10:10 PM
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Join Date: Oct 2014
Posts: 1
Fuel pressure/ pump problems

Ok guys I'm at a loss right now. I have a 1991 yj 2.5l 5 speed MPI. Since I haven't owned it (almost a year now) I've always had a problem with long starts if I leave the jeep for a few hours or overnight. finally got looking into the problem today and heres what I found: fuel pressure on the rail is 0 after sitting for awhile. After flipping the key to on 10 times the pressure builds to 12psi or so. Once starting (still is a long start) the pressure rises to around 22-23psi or so. If I pull the vacume line on the rail the psi doesn't change at all. If I turn it off the pressure slowly bleeds off maybe 1 or 2 psi per minute. I dropped the tank in search of a check valve only to find that I have the square style fuel pump assembly mout that doesn't have a check valve. I pulled out the pump to look it over (po said they replaced the pump which it does look newer, but I'm not ruling out the it could have went bad already.) Any ideas of what is causing my starting issue? Also how does the system keep pressure?

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