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Old 12-18-2012, 08:44 PM   #1
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Fuel Pressure

So here is the problem. My 98 wrangler 4.0 will drop fuel pressure without warning. I have changed both fuel pump and FPR along with all in tank filters. I have also swapped between three different fuel pump relays. After changing the pump it ran great for about 2 weeks. After changing FPR it worked great for about a week. Any thoughts?

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Old 12-18-2012, 09:06 PM   #2
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Whose fuel pressure regulator did you install? Sounds like you got one that went bad after you installed it. I had a FPR that came bad out of the box & it really screwed me up for a month thinking I had a different problem since the symptom I thought pointed to a bad FPR didn't change after installing the new FPR.

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Old 12-18-2012, 09:41 PM   #3
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Quote:
Originally Posted by Jerry Bransford
Whose fuel pressure regulator did you install? Sounds like you got one that went bad after you installed it. I had a FPR that came bad out of the box & it really screwed me up for a month thinking I had a different problem since the symptom I thought pointed to a bad FPR didn't change after installing the new FPR.
Look at this on eBay:

NEW STANDARD SMP FUEL FILTER PRESSURE REGULATOR PR318

http://bit.ly/ZM3V4U

I thought that might be it, or possibly the fuel pump has too much pressure, it's a Walbro 255
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Old 12-18-2012, 10:18 PM   #4
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Originally Posted by 4wd4GOD View Post
...or possibly the fuel pump has too much pressure, it's a Walbro 255
The fuel pump produces excess pressure by design; that's why the fuel pressure regulator exists.
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Old 12-18-2012, 10:25 PM   #5
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Quote:
Originally Posted by tangofox007

The fuel pump produces excess pressure by design; that's why the fuel pressure regulator exists.
I understand that, but stock parts are still built with limitations and this pump produces more psi than a stock one. This problem has been a thorn for a month or so, just trying to think of any possibility:/
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Old 12-18-2012, 10:30 PM   #6
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Have you tried just eliminating the regulator and seeing if the pump is working? What about the pick up, i know if they arent positioned right it will affect flow also.
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Old 12-18-2012, 10:34 PM   #7
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Originally Posted by krisbman
Have you tried just eliminating the regulator and seeing if the pump is working? What about the pick up, i know if they arent positioned right it will affect flow also.
The pump provides pressure every time the key is turned. The FPR is positioned properly, the pressure drops at idle randomly, and I've even had it cut out randomly driving also.
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Old 12-19-2012, 12:39 PM   #8
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If you have changed the pump the problem must be somewhere else. I'd check for loose connections particularly grounding wires.
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Old 12-19-2012, 01:23 PM   #9
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I wouldn't rule out that your replacement fuel pump could be faulty.

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