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Unread 02-17-2014, 11:57 AM   #1
mylogylo
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1994 YJ Wrangler 
 
Join Date: May 2007
Location: Dillon, Colorado
Posts: 367
Fuel pressure questions

The jeep has not been running so smooth lately so I wanted to check some things out. First I checked the fuel pressure.

At the rail. When I turned the key on it popped up to 39 psi and very slowly started to go down. Dropped to about 30 after a couple of minutes.

When I started it, cold btw, it idles between 62 and 64 PSI.

Does that sound pretty normal? Everything I read says the pressure at idle should be way lower.

I also got codes 14 map sensor and 21 oxygen sensor...odd that they both popped up at the same time.

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Unread 02-17-2014, 12:07 PM   #2
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,967
No, that is very very high. You should have 31 psi idle running. You need to check and see if the return line is pinched or the issue is the regulator. Pull the return line off the fuel rail. put a hose on the fuel rail and put it into a gas can. Hook up your pressure guage and then with the guage in sight start it. If the pressure is 31 then the return line is plugged. If it is still high the regulator is bad. Clear your codes by disconnecting the battery and see what you get after you have fixed the fuel problem. The 21 is probably related to your fuel problem.
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Unread 02-17-2014, 02:10 PM   #3
mylogylo
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1994 YJ Wrangler 
 
Join Date: May 2007
Location: Dillon, Colorado
Posts: 367
So I pulled the return line...I think...closest to the front...I'm sure it is because gas came out when running. Anyways, with the line pulled it read around 36psi at idle. I did just replaced the rubber hoses going to the tank about a month ago so I thought I'd drop it and see if they were pinched. The all look good. With the tank dropped and the return line hooked back up I still am reading a little above 60 PSI. Any suggestions? I am scratching my head. The hoses shouldn't really collapse since the return line is pressurized right?
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Unread 02-17-2014, 03:58 PM   #4
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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It is probably the return line hitting the bottom off the tank. Pull the line back at the tank and check it again. If it's 31 with it disconnected then post back and we can go from there.
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Unread 02-17-2014, 04:25 PM   #5
mylogylo
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1994 YJ Wrangler 
 
Join Date: May 2007
Location: Dillon, Colorado
Posts: 367
It's 35-36PSI with the line pulled at the rail. I reattached at the rail and pulled the hose at the tank. 35-36PSI. I can blow through the line from the rail with it disconnected at the tank with ease. So I guess it has to be in the tank. Guessing I just pull the pump and trim the return tube at the bottom? Thanks for your help BTW!
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Unread 02-17-2014, 04:42 PM   #6
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,967
two inches should do it
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Unread 02-17-2014, 05:30 PM   #7
mylogylo
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1994 YJ Wrangler 
 
Join Date: May 2007
Location: Dillon, Colorado
Posts: 367
That did the trick it seems! Wonder how long that crap has been going on LOL. Just gotta tighten her up and open a beer. Thanks again!!!!!!!
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Unread 02-17-2014, 07:39 PM   #8
Que89YJ
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1989 YJ Wrangler 
 
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Location: Detroit, Michigan
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Your welcome.
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